totally integrated power protection

TOTALLY INTEGRATED POWER BY SIEMENS

8

P R O T E C T I O NA N D S U B STAT I O N C O N T R O L

General overview

Three trends have emerged in thesphere of power automation: distrib-uted intelligent electronic devices(IEDs), open communication and PC-assisted HMIs. Numerical relays andcomputerised substation control arenow state-of-the-art.

The multitude of conventional, indi-vidual devices prevalent in the pastas well as comprehensive parallelwiring are being replaced by a smallnumber of multifunctional deviceswith serial connections.

One design for all applications

In this respect, Siemens offers a uni-form, universal technology for the en-tire functional scope of secondaryequipment, both in the constructionand connection of the devices and intheir operation and communication.This results in uniformity of design,coordinated interfaces and the sameoperating concept being establishedthroughout, whether in power sys-tem and generator protection, inmeasurement and recording sys-tems, in substation control and pro-tection or in telecontrol.

All devices are highly compact andimmune to interference, and aretherefore also suitable for direct in-stallation in switchgear cells. Further-more, all devices and systems arelargely self-monitoring, which meansthat previously costly maintenancecan be reduced considerably.

0203


8 Protection andSubstation Control

Fig. 8/1 The digital SICAM substation control system implements all of the control, measurement and automation functions of a substation. Protective relays are connected serially.

Auto-mation

Configuration andparameterisation

SIPROTEC:– relays– field control

devices– measuring

transducers– etc.

Monitoringand control

SICAM WinCC

PROFIBUS

GPS

System control centresIEC 60870-5-101

SICAM plusTools

IEC 60870-5-103

O.F.

RS485line

Protective relay

Photo 8/1 Protection and control in medium-voltage substations

Entire technology from onepartner

The Siemens Power Transmissionand Distribution Group supplies de-vices and systems for:

C Power system protectionC Substation controlC Remote control (RTUs)C Measurement and recordingC Monitoring and conditioning of

power quality

This covers all of the measurement,control, automation and protectionfunctions for substations.

Furthermore, our activities cover:C ConsultingC PlanningC DesignC Commissioning and Service

This uniform technology ”all fromone source“ saves the user time andmoney in the planning, installationand operation of his substations.

System protection

Siemens offers a complete spectrumof multifunctional, numerical relaysfor all applications in the field of net-work and machine protection.

Uniform design and a metal-enclosedconstruction with conventional con-nection terminals which is free fromelectromagnetic interference in ac-cordance with public utility require-ments assure simple system designand usage just as with conventionalrelays.

Numerical measurement techniquesensure precise operation and neces-sitate less maintenance thanks totheir continuous self-monitoring capa-bility. The integration of additionalprotective and other functions, suchas real-time operational measure-ments, event and fault recording, allin one unit economises on space, de-sign and wiring costs.

Setting and programming of the de-vices can be performed through theintegral, plain-text, menu-guided op-erator display or by using the com-fortable PC program DIGSI®.

For communication at telecontrol or substation control level, devices of the SIPROTEC 4 group can beequipped with exchangeablecommunications modules. Besidesan optimal integration in the SICAM SAS substation controlsystem using PROFIBUS FMS, thenamed IEC 60 870-5-103 protocoland PROFIBUS-DP, DNP 3.0 as wellas Modbus are supported.

Thus, the on-line measurements andfault data recorded in the protectiverelays can be used for local and re-mote control or can be transmittedvia telephone modem connections to the workplace of the service engi-neer.

Siemens supplies individual devicesas well as complete protection sys-tems in factory-finished cubicles. Forcomplex applications, type and de-sign test facilities are available to-gether with an extensive and com-prehensive network model using themost modern simulation and evalua-tion techniques.

8

by means of SCADA-like operation controland high-performance, uniformly operable PC toolsRationalisation of operation

by means of integration of many functionsinto one unit and compact equipment design

Savings in terms of spaceand costs

by means of uniform design,coordinated interfaces and universallyidentical EMC

Simplified planningand operationalreliability

Efficient parameterisationand operation

by means of PC tools with uniform operatorinterface

High levels of reliabilityand availability

by means of type-tested system technology, completeself-monitoring and the use of proven technology– 20 years of practical experience with digital protection,

more than 200,000 devices in operation (2000)– 15 years of practical experience with substation

automation (SINAUT LSA and SICAM), over1500 substations in operation (2000)

Fig. 8/2 For the user, the “entire technology from one partner” has many advantages

Substation control

The digital substation control sys-tems SICAM and SINAUT LSA pro-vide all control, measurement andautomation functions (e.g. transformertap changing) required by a switchingstation. They operate with distributedintelligence. Communication be-tween feeder-located devices andcentral unit is made via interference-free fibre-optic connections.

Devices are extremely compact andcan be built directly into medium- andhigh-voltage switchgear.

To enter data, set and program thesystem, the PC program SICAMPlusTools is available. The SICAMengineering tools are modelled onWINDOWS and SIMATIC productsthroughout, thus ensuring “ease ofuse”.

The operator interface is menu-guided, with SCADA-comparablefunctions, that is, with a level of con-venience which was previously onlyavailable in a network control centre.Optional telecontrol functions can beadded to allow coupling of the sys-tem to one or more network controlcentres.

In contrast to conventional substationcontrol systems, digital technologysaves enormously on space andwiring. SICAM and LSA systems aresubjected to full factory tests and aredelivered in ready for operation. Fur-thermore, the SICAM SAS has a sys-tem-wide time resolution of 1 ms.

Due to the special requirements ofmedium- and high-voltage systems,bay units and I/O modules withstandvoltages up to 2 kV.

0405


Substation automationSICAM

Power qualitySIMEAS

Line and generator protectionSIPROTEC

SICAM SASSubstation automationsystems, LAN-based(PROFIBUS)

Feeder protectionovercurrent/overload relays7SJ4 and 7SJ6

Line protectiondistance relays7SA5 and 7SA6

Busbar protection7SS5, 7SS6 and 7VH8

Generator/motor protection7SS5, 7SS6 and 7UM6

Transformer protection7UT5 and 7UT6

Protection and substationautomation

SIMEAS RFault recorders(oscillostores)

SICAM PCCEnergy automationbased on PC and LAN(PROFIBUS)

SIMEAS QPower qualityrecorders

SIMEAS TMeasuringtransducers

Line protectionpilot protectionrelays7SD5 and 7SD6

SICAM RTUSICAM miniRTUSICAM microRTURemote terminal units

Fig. 8/3 Product range for protection and substation control systems by Siemens

Remote Terminal Units

Siemens RTUs fulfil all the classicfunctions of remote measurementand control. Furthermore, because of the powerful microprocessors with 32-bit technology, they providecomprehensive data pre-processing,automation functions and bulkstorage of operational and faultinformation.

In the classic case, connections tothe switchgear are made throughcoupling relays and transducers. Thismethod allows an economicallyfavourable solution when mod-ernising or renewing the secondarysystems in older installations. Alter-natively, especially for new installa-tions, direct connection is also possi-ble. Digital protection devices can beconnected by serial links throughfibre-optic conductors or bus systems.

Switchgear interlocking

The distributed substation controlsystem SICAM SAS provides theoption to realise bay-specific and‘inter-bay’ interlocking by means of on-screen graphic planning. The substation topology as well as infeed conditions are taken intoconsideration. It prevents falseswitching, thus enhancing the safetyof operating personnel and equip-ment considerably.

Power quality (measuring and recording)

The SIMEAS® product range offersequipment for the monitoring ofpower supply quality (harmonic con-tent, distortion factor, peak loads,power factor, etc.), fault recorders(oscillostore), data logging printersand measuring transducers.

Stored data can be transmitted man-ually or automatically to PC evalua-tion systems where they can beanalysed by intelligent programs. Ex-pert systems are also applied here.This leads to rapid fault analysis andvaluable indicators for the improve-ment of network reliability.

For local bulk data storage and trans-mission, the central processorDAKON can be installed at substationlevel. Data transmission circuits foranalog telephone or digital ISDN net-works are incorporated as standard.Connection to local or wide-area net-works (LAN, WAN) is equally possi-ble.

We also have the SIMEAS T series ofcompact and powerful measuringtransducers with analog and digitaloutputs.

Advantages for the user

The concept of the “entire technol-ogy from one partner” offers theuser many advantages:

C High-level security for his systemsand operational rationalisationpossibilities

C Powerful system solutions with themost modern technology

C Compliance with internationalstandards

C Integration in the overall systemSIPROTEC-SICAM-SIMATIC

C Space and cost savingsC Integration of many functions into

one unit and compact equipmentpackaging

C Simple planning and safe operationC Unified design, matched interfaces

and EMI security throughoutC Rationalised programming and

handlingC Windows-based PC tools and

unified keypads and displaysC Fast, flexible mounting and

reduced wiringC Simple, fast commissioning

8

C Effective spare part stocking, highflexibility

C High-level operational security andavailability

C Continuous self-monitoring andproven technology:

C 20 years digital relay experience(more than 200,000 units in opera-tion)

C 15 years of digital substation con-trol (more than 1800 systems inoperation)

C Rapid problem solvingC Comprehensive support and fast

response from local sales andworkshop facilities worldwide.

Application hintsAll devices and systems for protec-tion, metering and control mentionedherein are designed to be used in theharsh environment of electrical sub-stations, power plants and the vari-ous industrial application areas.

When the devices were developed,special emphasis was placed on thedesign of electromechanical inter-faces (EMI). The devices are in ac-cordance with IEC 60 255 standards.Detailed information is contained inthe device manuals.

Reliable operation of the devices isnot affected by the usual interferencefrom the switchgear, even when thedevice is mounted directly in a low-voltage compartment of a medium-voltage switchgear panel.

It must, however, be ensured thatthe coils of auxiliary relays located on the same panel, or in the samecubicle, are fitted with suitable spike-quenching elements (e.g. free-wheeling diodes).

When used in conjunction withswitchgear for up to 1 kV or above,all external connection cables shouldbe fitted with a screen earthed atboth ends and capable of carryingcurrents. That means that the crosssection of the screen should be atleast 4 mm2 for a single cable and 2.5 mm2 for multiple cables in onecable duct.

All equipment proposed in this guideis built up either in closed housings(type 7XP20) or cubicles with protec-tion degree IP 51 according to IEC 60 529:

C Protected against access to dange-rous parts with a wire

C Sealed against dustC Protected against dripping water

Climatic conditions

C Permissible temperature duringservice–5 °C to +55 °C Permissible temperature duringstorage–25 °C to +55 °CPermissible temperature duringtransport–25 °C to +70 °C

C Permissible humidity Mean value per year ≤ 75% relativehumidity; on 30 days per year 95%relative humidity; condensation notpermissible

We recommend that units be in-stalled such that they are not sub-jected to direct sunlight, nor to largetemperature variations which maygive rise to condensation.

0607


Photo 8/2 Installation of the numericalprotection in the door of the low-voltage section of a medium-voltage

Mechanical stress

Vibration and shock during opera-tionC Standards:

IEC 60255-21 and IEC 60068-2C Vibration:

sinusoidal IEC 60255-21-1, class 110 Hz to 60 Hz: ± 0.035 mm amplitude; IEC 60068-2-6 60 Hz to 150 Hz: 0.5 g accelerationsweep rate 10 octaves/min20 cycles in 3 orthogonal axes

Vibration and shock duringtransportC Standards:

IEC 60255-21 and IEC 60068-2C Vibration

sinusoidalIEC 60255-21-1, class 25 Hz to 8 Hz: ± 7.5 mm amplitude;IEC 60068-2-68 Hz to 150 Hz: 2 g accelerationsweep rate 1 octave/min20 cycles in 3 orthogonal axes

C Shock IEC 60255-21-2, class 1IEC 60068-2-27

Insulation tests

C Standards:IEC 60255-5High-voltage test (routine test)2 kV (rms), 50 HzImpulse voltage withstand test(type test)all circuits, class III5 kV (peak); 1.2/50 µs; 0.5 J; 3 positive and 3 negative shots at intervals of 5 s

Electromagnetic compatibility

EC Conformity declaration (CEmark):All Siemens protection and controlproducts recommended in this man-ual comply with the EMC Directive99/336/EEC of the Council of the Eu-ropean Community and further rele-vant IEC 255 standards on electro-magnetic compatibility.

All products carry the CE mark.

EMC tests; immunity (type tests)

C Standards:IEC 60255-22 (product standard)EN 50082-2 (generic standard)

C High frequencyIEC 60255-22-1 class III– 2.5 kV (peak); 1 MHz; τ = 15 µs; 400 shots/s;duration 2 s

C Electrostatic discharge IEC 60255-22-2 class IIIand EN 61000-4-2 class III– 4 kV contact discharge; 8 kV air discharge; both polarities; 150 pF; Ri = 330 Ohm

C High-frequency electromagneticfield, nonmodulated;IEC 60255-22-3 (report) class III – 10 V/m; 27 MHz to 500 MHz

C High-frequency electromagneticfield, amplitude-modulated; ENV 50140, class III– 10 V/m; 80 MHz to 1000 MHz,80%; 1 kHz; AM

C High-frequency electromagneticfield, pulse-modulated;ENV 50140/ENV 50204, class III– 10 V/m; 900 MHz; repetition frequency 200 Hz; dutycycle 50%

C Fast transientsIEC 60255-22-4 and EN 61000-4-4,class III– 2 kV; 5/50 ns; 5 kHz; burst length 15 ms; repetition rate300 ms; both polarities; Ri = 50 Ohm; duration 1 min

C Conducted disturbances inducedby radio-frequency fields HF, amplitude-modulated ENV 50141, class III– 10 V; 150 kHz to 80 MHz; 80%; 1 kHz; AM

C Power-frequency magnetic field EN 61000-4-8, class IV – 30 A/m continuous; 300 A/m for 3 s; 50 Hz

EMC tests; emission (type tests)

C Standard:EN 50081-2 (generic standard)

C Interference field strength CISPR11, EN 55011, class A

C 30 MHz to 1000 MHzC Conducted interference voltage,

aux. voltage CISPR 22, EN 55022,class B– 150 kHz to 30 MHz

8

Transducers

Measuring transducers must complywith the applicable IEC recommenda-tions IEC 60044, formerly IEC 60185(current transformers) and 186 (po-tential transformers), ANSI/IEEEC57.13 or other comparable stand-ards.

Potential transformers

Potential transformers (p.t.) in single-or double-pole design for all primaryvoltages have single or dual second-ary windings of 100, 110 or 120 V/ √3,with output ratings between 10 and300 VA, and accuracies of 0.2, 0.5 or1% to suit the particular application.

Current transformers

Current transformers (c.t.) are usuallyof the single-ratio type with wound orbar-type primaries of adequate ther-mal rating. Single, dual or triple sec-ondary windings of 1 or 5 A arestandard. 1 A rating, however, shouldbe preferred, particularly in HV andEHV stations, to reduce the burdenof the connecting leads. Outputpower (rated burden in VA), accuracyand saturation characteristics(accuracy-limiting factor) of the cores and secondary windings must meet the particular application.

The current transformer classificationcode of IEC is used in the following:

Measuring coresThey are normally specified with0.5% or 1.0% accuracy (class 0.5 Mor 1.0 M), and an accuracy limitingfactor of 5 or 10. The required outputpower (rated burden) must be higherthan the actually connected burden.Typical values are 5, 10, 15 VA.Higher values are normally not neces-sary when only electronic meters andrecorders are connected.

A typical specification could be: 0.5M 10, 15 VA.

Cores for revenue meteringIn this case, class 0.2 M is normallyrequired.

Protection cores:The size of the protection core de-pends mainly on the maximum short-circuit current and the total burden(internal c.t. burden, plus burden ofconnecting leads, plus relay burden).

Further, an overdimensioning factorhas to be considered to cover the in-fluence of the DC component in theshort-circuit current.

In general, an accuracy of 1% (class5 P) is specified. The accuracy limit-ing factor KALF should normally bedesigned so that at least the maxi-mum short-circuit current can betransmitted without saturation (DCcomponent not considered).

This results, as a rule, in rated accu-racy limiting factors of 10 or 20 de-pendent on the rated burden of thecurrent transformer in relation to theconnected burden. A typical specifi-cation for protection cores for distri-bution feeders is 5P10, 15 VA or5P20, 10 VA.

The requirements for protective cur-rent transformers for transient per-formance are specified in IEC 60044-6.The recommended calculation proce-dure for saturation-free design, how-ever, leads to very high current trans-former dimensions. In many practicalcases, the current transformers can-not be designed to avoid saturationunder all circumstances because ofcost and space reasons, particularlywith metal-enclosed switchgear.

The Siemens relays are therefore de-signed to tolerate current transformersaturation to a large extent. The nu-merical relays proposed in this guideare particularly stable in this case dueto their integral saturation detectionfunction.

The required current transformer ac-curacy-limiting factor KALF can be de-termined by calculation, as shown intable 8/4.

The overdimensioning factor KOFdepends on the type of relay and theprimary DC time constant. For thenormal case, with short-circuit timeconstants lower than 100 ms, thenecessary value for K*ALF can betaken from the table in table 8/1. Therecommended values are based onextensive type tests.

0809


8

KALF : Rated c. t. accuracy-limiting factor

K*ALF : Effective c. t. accuracy-limiting factor

RBN : Nominal burden resistance

RBC : Connected burden

Ri : Internal c. t. burden(resistance of the c. t.secondary winding)

Iscc.max. = Maximum short-circuit currentIN = Nominal primary c. t. currentKOF = Overdimensioning factor

RBC + Ri

RBN + Ri

KALF> K*ALF

Icss.max.K*ALF>

IN

KOF

with:

Example:IEC 60185: 600/1, 15 VA, 5P10, Ri = 4 Ohm

(RNC + Ri) • I2N • KALFUKN =

1.3

BS 3938 : UKN = (15 + 4) • 1 • 10 = 146 V1.3

Ri = 4 Ohm

I2N = Nominal secondary current

Example:IEC 60 185: 600/5, 25 VA, 5P20,

20Vs.t. max = 20 x 5 A x RBN •

KALF

with:

RBN = PBN

INsec

2and I

Nsec = 5 A

we get

Vs.t. max = PBN • KALF

5

Vs.t. max = 25 • 20 =5

ANSI C57.13:

= 100, i.e. class C100

Relay type Minimum K*ALF

o/c protection7SJ4, 7SJ60, 61,62, 63

, minimum 20IHigh setpoint

IN

Transformerdifferential protection7UT61

Line differential(fibre-optic) protection7SD6/7SD52

and

Iscc. max. (close-in fault)

IN

aDistance protection7SA6, 7SA522

Iscc. max. (line-end fault)

IN

b

Iscc. max. (through fault)

IN

Numerical busbarprotection (low imped-ance type) 7SS5, 7SS6*

=

=

=

=

1

2

, minimum 30Iscc. max. (through fault)

IN

=

andIscc. max. (through fault)

IN

K*ALF (line end 1)

K*ALF (line end 2)

3

4<=

4

3

>40 for �<100 ms,

>50 for � >100 ms

<

a = 1 for �<30 ms

a = 2 for �<50 ms

a = 4 for �<200 ms

Line differential(pilot wire) protection7SD502/503/600

and

time to saturation >3 ms

KOF of strongest and weakest c.t. should not differ more than 500 %

If {(Iscc. max. (through fault)) / IN} >100, then K*ALF ≤100

* minimum restrainingfactor 0,6

b = 4 for �<30 ms

b = 5 for �<200 ms

Table 8/3 ANSI current transformer defini-tion

Table 8/2 BS current transformer definition

Table 8/1 Current transformer dimensioningformulae

Current transformer dataaccording to BS 3938In this case, the current transformeris defined by the knee-point voltageUKN and the internal secondary resist-ance Ri. The design values accordingto IEC 60 185 can be approximatelytransferred into the BS standarddefinition by the following formula.

Current transformer dataaccording to ANSI/IEEE C 57.13Class C of this standard defines thecurrent transformer by its secondaryterminal voltage at 20 times nominalcurrent, for which the ratio error shallnot exceed 10%. Standard classesare C100, C200, C400 and C800 for 5 A nominal secondary current.

Table 8/4 Required accuracy-limiting factor K*ALF

This terminal voltage can be approxi-mately calculated from the IEC dataas follows:

Relay burden

The current transformer burdens ofthe numerical relays of Siemens arebelow 0.1 VA and can therefore beneglected for a practical estimation.Exceptions are the 7SS50 busbar pro-tection (1.5 VA) and the pilot wire re-lays 7SD502, 7SD600 (4 VA) and7SD503 (3 VA + 9 VA per 100 Ohmpilot wire resistance).

Intermediate current transformersare normally no longer applicable asthe ratio adaptation for busbar andtransformer protection is numericallyperformed in the relay.

Analog static relays in general alsohave burdens below about 1 VA.

Mechanical relays, however, have amuch higher burden, up to the orderof 10 VA. This has to be consideredwhen older relays are connected tothe same current transformer circuit.In any case, the relevant relay manu-als should always be consulted forthe actual burden values.

Burden of the connection leads

The resistance of the current loopfrom the current transformer to therelay has to be considered:

1011


2K*ALF >

150 = 25

7SS5

I scc.max. = 30 kA

l = 50 mA = 6 mm2

600/1,5 P 10,15 VA,Ri = 4 Ohm

50=Iscc.max.

IN

30,000

600=

Result:The rated KALF Factor (10) is higher thanthe calculated value (7.6).Therefore, the stability criterium isfulfilled.

Rl6

=2 0.0179 50

0.3 Ohm=

RBC = Rl + RRelay =

= 0.3 + 1.5 = 1.8 Ohm

Given case:

According to Table 8/4:

15 + 4KALF >

1.8 + 425 = 7.6

1 A2RBN =

15 VA= 15 Ohm

1 A2RRelay =

1.5 VA= 1.5 Ohm

Example: Stability verification of thenumerical busbar protection 7SS50

AR l =

2 ρ lOhm

l = single conductor lengthfrom the c. t. to the relay in m

Specific resistance:

ρ = 0.0179 (copper wires)

A = conductor cross sectionin mm2

Ohm mm2

m

Table 8/5 Resistance of the current loop

Fig. 8/4 Example current transformer test

8.1 Power SystemProtectionIntroduction

Siemens is one of the world’s leadingsuppliers of protective equipment forpower systems.

Thousands of relays ensure first-classperformance in the transmission anddistribution networks on all voltagelevels all over the world, in countriesof tropical heat and arctic frost.

For many years, Siemens has alsosignificantly influenced the develop-ment of protection technology.

In 1976, the first minicomputer(process-computer)-based protectionsystem was commissioned: A totalof 10 systems for 110/20-kV substa-tions were supplied and are workingsatisfactorily today.

Today, Siemens offers a completeprogram of protective relays for allapplications including numerical bus-bar protection.

To date, more than 200,000 numeri-cal protection relays from Siemensare providing successful service, asstand-alone devices in traditional sys-tems or as components of coordi-nated protection and substation con-trol.

Meanwhile, the innovative SIPROTEC 4series has been launched, incorpo-rating the many years of operationalexperience with thousands of relays,together with users’ requirements(power authority recommendations).

State of the art

Mechanical and solid-state (static)relays have been almost completelyphased out of our production be-cause numerical relays are nowpreferred by the users.

Advantages

C Compact design and lower costdue to integration of many func-tions into one relay

C Hohe Verfügbarkeit selbst beigeringerer Wartung auf Grundintegrierter Selbstüberwachung

C Keine Nullpunktabweichung (Alte-rung) der Messkennlinien wegender vollständig digitalen Verarbei-tung

C High availability even with lessmaintenance due to digital filteringand optimised measuring algo-rithms

C Many integrated add-on functions,for example for load-monitoringand event/fault recording

C Local operation keypad and displaydesigned to modern ergonomic cri-teria

C Easy and secure read-out of infor-mation via serial interfaces with aPC, locally or remotely

C Possibility to communicate withhigher-level control systems usingstandardised protocols (open com-munication)

Modern protection management

All the functions, for example, of aline protection scheme can be incor-porated in one unit:C Distance protection with associat-

ed add-on and monitoring functionsC Universal teleprotection interfaceC Autoreclose and synchronism

check

8

Photo 8/3 SIPROTEC 4 numerical relays bySiemens

Protection-related information can becalled up on-line or off-line, such as:C Distance to faultC Fault currents and voltagesC Relay operation and data (fault-de-

tector pickup, operating times etc.)C Set valuesC Line load data (kV, A, MW, kVAr)

To fulfil vital protection redundancyrequirements, only those functionswhich are interdependent and di-rectly associated with each other areintegrated in the same unit. For back-up protection, one or more additionalunits have to be provided.

All relays can stand fully alone. Thus,the traditional protection concept ofseparate main and alternate protec-tion as well as the external connec-tion to the switchyard remain un-changed.

“One feeder, one relay” concept

Analog protection schemes havebeen engineered and assembledfrom individual relays. Interwiring be-tween these relays and scheme test-ing have been carried out manually inthe workshop.

Data sharing now allows for the inte-gration of several protection tasksinto one single numerical relay. Onlya few of external devices may berequired for completion of the totalscheme. This has significantly low-

ered the costs of engineering, as-sembly, panel wiring, testing andcommissioning. The reliability of theprotection scheme has been highlyincreased.

Engineering has moved fromschematic diagrams towards aparameter definition procedure. The documentation is provided bythe relay itself. Free allocation of LED operation indicators and outputcontacts provides more applicationdesign flexibility.

1213


Relay monitor

01.10.93

BM

Serial link to station – or personal computer

SM ER FR2579FL67N21

to remote line end kA,kV,Hz,MW,MVAr,MVA

85

Loadmonitor

52

ANSI No.*)522167NFL792585SMERFRBM*) see Table 8/6 cont.

Circuit-breakerDistance protectionDirectional ground-fault protectionDistance-to-fault locatorAutoreclosureSynchro-checkCarrier interface (teleprotection)Self-monitoringEvent recordingFault recordingBreaker monitor

Fault record

Fault report

Breaker monitor

Supervisory control

Fig. 8/5 Numerical relays, increased availability of information

Measuring function included

The additional transducer was ratherused for protecting measuring instru-ments under system fault conditions.Due to the low thermal withstand ca-pability of the measuring instru-ments, they could not be connectedto the protective current transformerdirectly. Consequently, additionaltransducers and measuring instru-ments are now only necessary wherehigh accuracy is required, e.g. for rev-enue metering.

Remote interrogation

A powerful serial data link providesfor interrogation of digitised meas-ured values and other informationstored in the protection units, forprintout and further processing at thesubstation or system control level. Inthe opposite direction, settings maybe altered or test routines initiatedfrom a remote control centre.

For greater distances, especially inoutdoor switchyards, fibre-optic ca-bles are preferably used. This tech-nique has the advantage that it is to-tally unaffected by electromagneticinterference.

HMI of numerical relays

A simple built-in operator key padwhich requires no special softwareknowledge or code word tables isused for parameter input and read-out.

8

Protection Laptop

RecordingPersonal computer

Assigning

Recording andconfirmation

DIGSI

DIGSI

System level to remote control

Substation level

Modem(option)

Bay level

Data collectiondevice

ERTU

Control

Coordinatedprotection andcontrol

RTU

Relay

52

Fig. 8/7 Communication options

Fig. 8/6 PC-aided setting procedure of numerical protection relays

This allows operator dialog with theprotective relay. Answers appearlargely in plain text on the display ofthe operator panel. Dialog is dividedinto three main stages:C Input, alteration and readout of set-

tingsC Testing the functions of the protec-

tion device and C Readout of relay operation data for

the three last system faults and theautoreclose counter.

Modern system protection man-agement

A notebook PC may be used for up-graded protection management.

The MS Windows-compatible relayoperation program DIGSI is availablefor entering and readout of setpointsand archiving of protection data.

The relays may be set in 2 steps.First, all relay settings are prepared inthe office with the aid of a local PCand stored on a floppy or the harddisk. At site, the settings can then bedownloaded from a PC into the relay.The relay confirms the settings andthus provides an unquestionablerecord.

Vice versa, after a system fault, therelay memory can be uploaded to aPC, and comprehensive fault analysiscan then take place in the engineer’soffice.

Alternatively, the total relay dialogcan be guided from any remote loca-tion through a modem-telephone con-nection (Fig. 8/7).

1415


10 000setpoints

200setpoints

sub

bay

20setpoints

bay

4flags

OH line

1200flagsp. a.

system

1

1

1

300 faults p. a.approx. 6,000 kmOHL (fault rate:5 p. a. and100 km)

systemapprox.500relays

Relay operationsSetpoints

Fig. 8/8 System-wide setting and relay operation library

Fig. 8/9 Alternate parameter groups

Parameter

Line data

O/C Phase settings

O/C Ground settings

Fault recording

Breaker fail

1000

1100

1200

1500

280

3900

DParameter

Line data

O/C Phase settings

O/C Ground settings

Fault recording

Breaker fail

1000

1100

1200

1500

280

3900

CParameter

Line data

O/C Phase settings

O/C Ground settings

Fault recording

Breaker fail

1000

1100

1200

1500

280

3900

BParameter

Line data

O/C Phase settings

O/C Ground settings

Fault recording

Breaker fail

1000

1100

1200

1500

280

3900

A

Relay data management

Analog distribution-type relays havesome 20–30 setpoints. If we con-sider a power system with about 500relays, then the number adds up to10,000 settings. This requires consid-erable expenditure in setting the re-lays and filing retrieval setpoints.

A personal computer-aided man-ma-chine dialog and archiving program,e.g. DIGSI, assists the relay engineerin data filing and retrieval. The pro-gram files all settings systematicallyin substation-feeder-relay order.

Corrective rather than preventivemaintenance

Numerical relays monitor their ownhardware and software. Exhaustiveself-monitoring and failure diagnosticroutines are not restricted to the pro-tective relay itself, but are methodi-cally carried through from currenttransformer circuits to tripping relaycoils.

Equipment failures and faults in thecurrent transformer circuits are im-mediately reported and the protec-tive relay blocked.

Thus, the service personnel are nowable to correct the failure upon occur-rence, resulting in a significantly up-graded availability of the protectionsystem.

Adaptive relaying

Numerical relays now offer secure,convenient and comprehensivematching to changing conditions.Matching may be initiated either bythe relay’s own intelligence or fromthe outside world via contacts or se-rial telegrams. Modern numerical re-lays contain a number of parametersets that can be pre-tested duringcommissioning of the scheme (Fig.8/9). One set is normally operative.Transfer to the other sets can be con-trolled via binary inputs or serial datalink. There are a number of applica-tions for which multiple settinggroups can upgrade the scheme per-formance, e.g.

a) For use as a voltage-dependentcontrol of o/c relay pickup valuesto overcome alternator fault cur-rent decrement to below normalload current when the AVR is notin automatic operation.

b) For maintaining short operationtimes with lower fault currents,e.g. automatic change of settingsif one supply transformer is takenout of service.

c) For “switch-onto-fault” protectionto provide shorter time settingswhen energising a circuit aftermaintenance. The normal settingscan be restored automatically aftera time delay.

d) For autoreclose programs, i.e. in-stantaneous operation for first tripand delayed operation after unsuc-cessful reclosure.

e) For cold load pickup problemswhere high starting currents maycause relay operation.

f) For ”ring open“ or ”ring closed“operation.

8

8.2 Relay Design andOperationMode of operation

Numerical protective relays operateon the basis of numerical measuringprinciples. The analog measured val-ues of current and voltage are decou-pled galvanically from the plant sec-ondary circuits via input transducers(Fig. 8/10). After analog filtering, thesampling and the analog-to-digitalconversion take place. The samplingrate is, depending on the differentprotection principles, between 12and 20 samples per period. With cer-tain devices (e.g. generator protec-tion) a continuous adjustment of thesampling rate takes place dependingon the actual system frequency.

The protection principle is based on acyclic calculation algorithm, utilisingthe sampled current and voltage ana-log measured values. The fault detec-tion determined by this process mustbe established in several sequentialcalculations before protection reac-tions can follow.

A trip command is transferred to thecommand relay by the processor, util-ising a dual-channel control.

The numerical protection concept of-fers a multitude of advantages, espe-cially with regard to higher security,reliability and user friendliness, suchas:

C High measurement accuracy: The high utilisation of adaptive al-gorithms produce accurate resultseven during problematic conditions

C Good long-term stability:Due to the digital mode of opera-tion, drift phenomena at compo-nents due to ageing do not lead tochanges in accuracy of measure-ment or time delays

C Security against over- and under-function

With this concept, the danger of anundetected error in the device caus-ing protection failure in the event of anetwork fault is clearly reduced whencompared to conventional protectiontechnology. Cyclical and preventivemaintenance services have thereforebecome largely obsolete.

1617


Meas.inputs

Currentinputs(100 x /N,1 s)

Voltageinputs(140 Vcontinuous)

A/Dconverter

Processorsystem

Inputfilter

V.24serialinterfaces

PC interface – LSA interface

Memory:RAMEEPROMEPROM

Input/outputports

Input/outputunits

Binaryinputs

Alarmrelay

Com-mandrelay

LEDdis-plays0001

01010011

Amplifier

Input/outputcontacts

digital10 Vanalog

100 V/1 A,5 A analog

FO

Fig. 8/10 Block diagram of numerical protection

The integrated self-monitoring sys-tem (Fig. 8/11) encompasses the fol-lowing areas:C Analog inputsC Microprocessor systemC Command relays

Implemented functions

SIPROTEC relays are available with avariety of protective functions. Seerelay charts (page 25 cont.).

The high processing power of mod-ern numerical devices allow furtherintegration of non-protective add-onfunctions.

The question as to whether separateor combined relays should be usedfor protection and control cannot beuniformly answered. In transmissiontype substations, separation into in-dependent hardware units is still pre-ferred, whereas on the distributionlevel, a trend towards higher functionintegration can be observed. Here,combined feeder relays for protec-tion, monitoring and control are gain-ing ground (Photo 8/4).

Most of the relays of this manual arestand-alone protection relays. The ex-ception in the SIPROTEC 3 series isthe 7SJ531 distribution feeder relaythat also integrates control functions.Per feeder, only one relay package isneeded in this case leading to a con-siderable reduction in space andwiring.

With the new SIPROTEC 4 series(types 7SJ61, 62 and 63), Siemenssupports both stand-alone and com-bined solutions on the basis of a sin-gle hardware and software platform.

The user can decide within widelimits on the configuration of thecontrol and protection functions inthe feeder, without compromisingthe reliability of the protectionfunctions (Fig. 8/12).

8

Plausibility check of input quantitiese. g.iL1 + iL2 + iL3 = iE

uL1 + uL2 + uL3 = uE

Check of analog-to-digital conversionby comparison withconverted reference quantities

A

D

Hardware and software monitoring ofthe microprocessor system incl. memory,e.g. by watchdog and

cyclic memory checks

Micro-processorsystem

Monitoring of the tripping relaysoperated via dual channelsRelay

Tripping check or test reclosure by localor remote operation (not automatic)

Fig. 8/11 Self-monitoring system

Photo 8/4 Switchgear with numerical Switchgear with combined protection relay (7SJ62) and and control relay (7SJ63)traditional control

The following solutions are availablewithin one relay family:C Separate control and protection

relaysC Protective relays including remote

control of the feeder breaker viathe serial communication link

C Combined feeder relays for protec-tion, monitoring and control

Mixed use of the different relaytypes is easily possible on account ofthe uniform operation and communi-cation procedures.

1819


DIGSI 4

SICAMSAS

DIGSI 4

Telephoneconnection

PROFIBUS-FMS or IEC 60 870-5-1031)

Modem IEC 60 870-5-1, -2

IEC 60 870-5-1, -2

DIGSI 4

1)future new standard IEC 61850

47

7SJ61/62/63

7SJ62/63

Auto-reclosing

Local/Remote controlCommands/Feedback indications

Motorcontrol(only 7SJ63)

Communica-tions moduleRS23/485fibre opticIEC 60 870-5-103PROFIBUS FMS

Faultrecording

21FL

6467

5150 51N50N 4946

51N60N

79M

50BF

14

Breakerfailureprotection

Lockedrotor

Motor protection (option)Starting time

Startinhibit

Directional earth-faultprotection (option)

Rotating fieldmonitoring

Directional (option)

Metering values

Metered powervalues pulses

Calculated

V, Watts,Vars f.p.f.

I2 limit values

Vf (option)

Fault locator

PLC logic

74TC 86

Trip circuitmonitoring

Lockout

&

Busbar

HMI

4837 66/86

67N67

810/U 59

Inrushcurrentstabiliser

27

52

Fig. 8/12 SIPROTEC 4 relays 7SJ61/62/63, implemented functions

Fig. 8/13 SIPROTEC 4 relays, communication options

Integration of relays intosubstation automation

Basically, Siemens numerical relaysare all equipped with an interface toIEC 60870-5-103 for open communi-cation with substation control sys-tems either by Siemens (SICAM) orby any other supplier.

The relays of the newer SIPROTEC 4series, however, are even moreflexible and equipped with communi-cation options. SIPROTEC 4 relayscan still be connected to the SICAMsystem or to a communicationssystem of another supplier via IEC 60870-5-103.

SIPROTEC 4 relays can in this casebe connected to the PROFIBUSsubstation LAN of the SICAM systemvia one serial interface. Through asecond serial interface, e.g. IEC 60870-5-103, the relay can separatelycommunicate with a remote PC via amodem-telephone line (Fig. 8/13).

SIPROTEC 4 protection and SICAMstation control, which is based onSIMATIC, are of uniform design, andcommunication is based on thePROFIBUS standard.

HMI Human Machine Interface

All operator actions can be executedand information displayed on an inte-grated user interface.

Many advantages are already to befound on the clear and user-friendlyfront panel:C Ergonomic arrangement and

grouping of the keys C Large non-reflective back-lit displayC Programmable (freely assignable)

LEDs for important messagesC Arrows arrangement of the keys

for easy navigation in the functiontree

C Operator-friendly input of the set-ting values via the numeric keys orwith a PC by using the operatingprogram DIGSI 4

C Command input protected by key lock (6MD63/7SJ63 only) orpassword

C Four programmable keys forfrequently used functions “at the touch of a button”

8

Photo 8/5 Front view of the Front view of the combinedprotective relay 7SJ62 protection, monitoring and control

relay 7SJ63

1 Large illuminated display2 Cursor keys3 LED with reset key

4 Control (7SJ61/62 usesfunction keys)

5 Key switches

6 Freely programmablefunction keys

7 Numerical keypad

1

2

3

4

6

7

1

2

3

4

5

6

7

DIGSI 4 – the HMI program forSIPROTEC 4 relays

For the user, DIGSI is synonymouswith convenient, user-friendly para-meterising and operation of digitalprotection relays. DIGSI 4 is a logicalinnovation for operation of protectionand field control units of theSIPROTEC 4 family.

The PC operating program DIGSI 4 isthe human-machine interface be-tween the user and the SIPROTEC 4units. It features modern, intuitiveoperating procedures. With DIGSI 4,the SIPROTEC 4 units can be config-ured and queried.

C The interface provides you onlywith what is really necessary, irre-spective of which unit you are cur-rently configuring.

C Contextual menus for every situa-tion provide you with made-to-measure functionality – searchingthrough menu hierarchies is a thingof the past.

C Explorer – operation on the MSWindows 95® Standard – showsthe options in logically structuredform.

C Even with routing, you have theoverall picture – a matrix showsyou at a glance, for example, whichLEDs are linked to which protec-tion control function(s). It just takesa click with the mouse to establishthese links by a fingertip.

C Thus, you can also use the PC tolink up with the relay via star coup-ler or channel switch, as well viathe PROFIBUS® of a substationcontrol system. The integrated ad-ministrating system ensures clearaddressing of the feeders and re-lays of a substation.

C Access authorisation by means ofpasswords protects the individualfunctions, such as for example pa-rameterising, commissioning andcontrol, from unauthorised access.

C When configuring the operator en-vironment and interfaces, we haveattached importance to continuitywith the SICAM automation sys-tem. This means that you canreadily use DIGSI on the stationcontrol level in conjunction withSICAM. Thus, the way is open tothe SIMATIC automation world.

Marshalling matrix

The DIGSI 4 matrix allows the user tosee the overall view of the relay con-figuration at a glance. For example,you can display all the LEDs that arelinked to binary inputs or show exter-nal signals that are connected to therelay. And with one mouse click, con-nections can be switched.

Display editor

A display editor is available to designthe display on SIPROTEC 4 units. Thepredefined symbol sets can be ex-panded to suit the user. The drawingof a one-line diagram is extremelysimple. Load monitoring values (ana-log values) can be placed, if required.

Commissioning

Special attention has been paid tocommissioning. All binary inputs andoutputs can be read and set directly.This can simplify the wire checkingprocess significantly for the user.

2021


Photo 8/6 DIGSI manager

Photo 8/7 Function scope

Photo 8/8 The device with all its parametersand process data

CFC: graphic configuration

With the help of the graphical CFC(Continuous Function Chart) Tool, youcan configure interlocks and switch-ing sequences simply by drawing thelogic sequences; no special knowl-edge of software is required. Logicalelements such as AND, OR and timeelements are available.

Hardware and software platform

C Pentium 133 MHz or above, with atleast 32 Mbytes RAM

C DIGSI requires about 200 Mbyteshard disk space

C Additional hard disk space per in-stalled protection device 2 Mbytes

C One free serial interface to the pro-tection device (COM 1 to COM 4)

C One CD-ROM drive (required for in-stallation)

C WINDOWS 95/98 or NT 4

8

Photo 8/9 DIGSI 4 allocation matrix

Photo 8/10 Display editor

Photo 8/11 CFC logic with module library

Fault analysis

The evaluation of faults is simplifiedby numerical protection technology.In the event of a fault in the network,all events as well as the analogtraces of the measured voltages andcurrents are recorded.

The following types of memory areavailable:C 1 operational event memory

Alarms that are not directly assig-ned to a fault in the network (e.g.monitoring alarms, alternation of aset value, blocking of the automaticreclose function).

C 5 fault-event historiesAlarms that occurred during thelast 3 faults on the network (e.g.type of fault detection, trip com-mands, fault location, autoreclosecommands). A reclose cycle withone or more reclosures is treatedas one fault history. Each new faultin the network overrides the oldestfault history.

C A memory for the fault recordingsfor voltage and current. Up to 8fault recordings are stored. Thefault recording memory is organ-ised as a ring buffer, i.e. a newfault entry overrides the oldestfault record.

C 1 earth-fault event memory (optio-nal for isolated or impedance earth-ed networks) Event recording ofthe sensitive earth fault detector(e.g. faulty phase, real componentof residual current).

The time tag attached to the faultrecords is a relative time from faultdetection with a resolution of 1 ms.In the event of devices with inte-grated battery back-up clock, the op-erational events as well as the faultdetection are assigned the internalclock time and date stamp.

The memory for operational eventsand fault record events is protectedagainst failure of auxiliary supply withbattery back-up supply.

The integrated operator interface or aPC supported by the DIGSI program-ming tool is used to retrieve fault re-ports as well as for the input of set-tings and routing.

Evaluation of fault records

Readout of the fault record by DIGSIis done by fault-proof scanning proce-dures in accordance with the stand-ard recommendations for transmis-sion of fault records. A fault recordcan also be read out repeatedly. Inaddition to analog values, such asvoltage and current, binary tracks canalso be transferred and presented.

DIGSI is supplied together with theDIGRA (Digsi Graphic) program,which provides the customer withfull graphical operating and evaluationfunctionality like that of the digitalfault recorders (oscillostores) bySiemens (see Photo 8/12).

Real-time presentation of analog dis-turbance records, overlaying andzooming of curves and visualisationof binary tracks (e.g. trip command,reclose command, etc.) are also partof the extensive graphical functional-ity, as are setting of measurementcursors, spectrum analysis and faultresistance derivation.

Data security, data interfaces

DIGSI is a closed system as far asprotection parameter security is con-cerned. The security of the storeddata of the operating PC is ensuredby checksums. This means that it isonly possible to change data withDIGSI, which subsequently calculatesa checksum for the changed data andstores it with the data. Changes inthe data and thus in safety-relatedprotection data are reliably detected.

2223


Photo 8/12 Display and evaluation of a faultrecord using DIGSI

DIGSI is, however, also an open sys-tem. The data export function sup-ports export of parameterisation androuting data in standard ASCII format.This permits simple access to thesedata by other programs, such as testprograms, without endangering thesecurity of data within the DIGSI pro-gram system.

With the import and export of faultrecords in IEEE standard formatCOMTRADE (ANSI), a high-perform-ance data interface is producedwhich supports import and export offault records into the DIGSI partnerprogram DIGRA. This enables the ex-port of fault records from Siemensprotection units to customer-specificprograms via the COMTRADE for-mat.

Remote relay interrogation

The numerical relay range of Siemenscan also be operated from a remotelylocated PC via modem-telephoneconnection.

Up to 254 relays can be addressedvia one modem connection if the7XV53 star coupler is used as a com-munication node (Fig. 8/14).

The relays are connected to the starcoupler via optical fibre links. Everyprotection device which belongs to aDIGSI substation structure has aunique address.

The relays are always listening, butonly the addressed one answers theoperator command which comesfrom the central PC.

If the relay located in a station is tobe operated from a remote office,then a device file is opened in DIGSIand the protection dialog is chosenvia modem. After password input,DIGSI establishes a connection to theprotection device after receiving acall-back from the system.

This way, secure and time-savingremote setting and readout of dataare possible.

Remote diagnostics and control oftest routines are also possible with-out the need of on-site checks of thesubstation.

8

7XV53

7**67**57SJ60 7RW60 7SD60

RS485 Bus

opt.

RS485

DIGSIPC, centrally locatedin the substation(option)

DIGSIPC, remotely located

Modem

Office

Substation

AnalogISDN

Modem,optionally withcall-back function

Star coupler

Signal converter

Fig. 8/14 Remote relay communication

Enclosures and terminal systems

The protection devices and the corre-sponding supplementary devices areavailable mainly in 7XP20 housings.Installation of the modules in acubicle without the enclosure is notpermissible.

The width of the housing conformsto the 19" system with the divisions1/6, 1/3, 1/2 or 1/1 of a 19" rack. Thetermination module is located at therear of devices for panel flush mount-ing or cubicle mounting.

For electrical connection, screw ter-minals are provided.

The heavy-duty current plug connec-tors provide automatic short-circuit-ing of the current transformer circuitswhen the modules are withdrawn.Whenever secondary circuits of cur-rent transformers are concerned,special precautions are to be taken.

In the housing version for surfacemounting, the terminals are wired upon terminal strips on the top and bot-tom of the device. For this purposetwo-tier terminal blocks are used toattain the required number of termi-nals. According to IEC 60529, thedegree of protection is indicated bythe identifying IP, followed by anumber for the degree of protection.The first digit indicates the protectionagainst accidental contact andingress of solid foreign bodies, thesecond digit indicates the protectionagainst water. 7XP20 housings areprotected against ingress of danger-ous parts, dust and dripping water (IP 51).

For mounting of devices into switch-gear cubicles, standard cubicles arerecommended. The standard cubiclehas the following dimensions:

2200 mm x 900 mm x 600 mm (H x W x D). These cubicles are pro-vided with a 44 U high mounting rack(standard height unit U = 44.45 mm).It can swivel as much as 180° in aswing frame.

The rack provides for a mountingwidth of 19", allowing, for example, 2 devices with a width of 1/2 x 19" to be mounted. The devices in the7XP20 housing are secured to rails by screws. Module racks are notrequired.

2425


8

8.3 Relay Selection Guide

ANSINo.1)

1) ANSI (American National Standards Institute)/IEEE (Institute of Electrical and Electronic Engineers)C 37.2: IEEE Standard Electrical Power System Device Function Numbers

Description

Protective functions

Type

Table 8/6 Relay selection guide

Feeder control facilities

Feeder mimic display

14 Zero speed and underspeed dev.

21 Distance protection, phase

21N Distance protection, earth

24 Overfluxing (U/f)

25 Synchronism check

27 Undervoltage

81 Spannungs-/Frequenz-Schutz

32 Directional power

32F Forward power

32R Reverse power

37 Undercurrent or underpower

40 Field failure

46 Load unbalance, negative phasesequence overcurrent

47 Phase sequence voltage

48 Incomplete sequence, locked rotor, failure to accelerate

49 Thermal overload

49R Rotor thermal protection

49S Stator thermal protection

50 Instantaneous overcurrent

50N Instantaneous earth fault overcurrent

51N Earth overcurrent relay

79M

74TC

– – – – – – – – – – – – – ■ – – – – – – – –

■ ■ – – – – – – – – – – – – – – – – – – ■ ■

■ ■ – – – – – – – – – – – – – – – – – – – –

– – – – – – – – – – – – – – – – – – – – ■ ■

■ ■ – – – – – – – – – – – – – – – – – – – –

■ ■ – – – – – – – – – ■ ■ ■ – – – – – – ■ ■

– – – – – – – – – – – – – – – – – – – – – –

– – – – – – – – – – – – – – – – – – – – ■ ■

– – – – – – – – – – – – – – – – – – – – ■ ■

– – – – – – – – – – – – – – – – – – – – ■ ■

– – – – – – – – – – ■ ■ ■ ■ – – – – – – ■ ■

– – – – – – – – – – – – – – – – – – – – ■ ■

– – – – – – – – ■ ■ ■ ■ ■ ■ – – – – – – ■ ■

■ ■ – – – – – – – – – ■ ■ – – – – – – – ■ ■

– – – – – – – – ■ ■ ■ ■ ■ ■ – – – – – – – ■

■ – – ■ ■ ■ ■ – ■ ■ ■ ■ ■ ■ – ■ ■ – – – ■ ■

– – – – – – – – – – ■ ■ ■ ■ – – – – – – – –

– – – – – – – – – – ■ ■ ■ ■ – – – – – – ■ ■

■ ■ – – – – – ■ ■ ■ ■ ■ ■ ■ – ■ ■ – – – ■ ■

■ ■ – – – – – ■ ■ ■ ■ ■ ■ ■ – ■ ■ – – – – –

– – – – – – – ■ ■ ■ ■ ■ ■ ■ – ■ ■ – – – ■ ■

■ ■ – – – – – – ■ ■ – – – – – – – – – – – –

– – – – – – – – ■ ■ – – – – – – – – – – – –

Dis

tan

ce p

rote

ctio

n

Pil

ot

wir

ed

iffe

ren

tial

Fib

re-o

pti

c Li

ne

dif

fere

nti

al

Ove

rcu

rre

nt

Mo

tor

pro

tect

ion

Tra

nsf

orm

er

dif

fere

nti

al

Bu

szo

ne

Gen

erat

or

pro

tect

ion

7UM

61

7UM

62

7SS

52

7SS

60

7VH

83

7VH

60

7UT

612

7UT

613

7SJ6

2

7SJ4

5/96

7SJ6

0

7SJ6

02

7SJ6

1

7SJ6

2

7SJ6

3

7SD

61

7SD

522/

23

7SD

600

7SD

502

7SD

503

7SA

6

7SA

522

2627


Description


Type

ANSINo.1)

1) ANSI (American National Standards Institute)/IEEC (Institute of Electrical and Electronic Engineers)C 37.2: IEEE Standard Electrical Power System Device Function Numbers


Feeder control facilities

Feeder mimic dosplay

51GN Stator earth-fault overcurrent

51 Overcurrent with time delay

51N Earth-fault overcurrentwith time delay

59 Overvoltage

59N Residual voltage earth-faultprotection

64R Rotor earth fault

67 Directional overcurrent

67N Directional earth-faultovercurrent

67G Directional Stator earth-faultovercurrent

78 Out-of-step protection

79 Autoreclose

81 Frequency relay

85 Carrier interface

86 Lockout relay, start inhibit

87G Differential protection, generator

87T Differential protection, transf.

87B Differential protection, busbar

87M Differential protection, motor

87L Differential protection, line

87N Restricted earth-fault protection

92 Voltage and power directionalrelay

50BF Breaker failure

7UM

61

7UM

62

7SS

52

7SS

60

7VH

83

7VH

60

7UT

612

7UT

613

7SJ6

2

7SJ4

7SJ6

0

7SJ6

1

7SJ6

2

7SJ6

3

7SD

61

7SD

52/5

3/23

7SD

600

7SD

502

7SD

503

7SA

6

7SA

522

Dis

tan

ce p

rote

ctio

n

Pil

ot

wir

ed

iffe

ren

tial

Fib

re-o

pti

c Li

ne

dif

fere

nti

al

Ove

rcu

rre

nt

Mo

tor

pro

tect

ion

Tra

nsf

orm

er

dif

fere

nti

al

Bu

szo

ne

dif

fere

nti

al

Gen

erat

or p

rote

ctio

n

– – – – – – – – – – – – ■ – – – – – – ■ ■

■ ■ – ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ – ■ ■ – – – ■ ■

■ ■ – – – – – – – – – – ■ – – – – – – ■ ■

■ ■ – – – – – – – – ■ ■ ■ – – – – – – ■ ■

■ ■ – – – – – – – – ■ ■ – – – – – – – ■ ■

– – – – – – – – – – – – – – – – – – – ■ ■

– – – – – – – – – – ■ ■ – – – – – – – ■ ■

■ ■ – – – – – – – – ■ ■ ■ – – – – – – – –

– – – – – – – – – – – – – – – – – – – ■ ■

■ ■ – – – – – – – – – – – – – – – – – – ■

■ ■ – – – – ■ – ■ ■ ■ ■ – – – – – – – – –

– – – – – – – – – – ■ ■ – – – – – – – ■ ■

■ ■ – – – – – – – – – – – – – – – – – – –

■ ■ – – – – – – – ■ ■ ■ ■ – – – – – – ■ ■

– – – – – – – – – – – – – – ■ ■ – – – – ■

– – – – – – – – – – – – – – ■ ■ – – – – ■

– – – – – – – – – – – – – – – – ■ ■ ■ – –

– – – – – – – – – – – – – – ■ ■ – – ■ – ■

– – ■ ■ ■ ■ ■ – – – – – – – – – – – – – –

– – – – – – – – – – – – – ■ – ■ – – – – ■

– – – – – – – – – – – – – – – – – – – – –

■ ■ – – – – – ■ – ■ ■ ■ – – – – – – – ■ ■

8

Vo

ltag

e, f

req

uen

cy

7VK

512

7VE

51

7SV

512

7SV

600

7RW

600

Bre

aker

fai

lure

Description


Syn

chro

nis

ing

Au

tore

clo

se +

syn

chro

nis

m c

hec

k

Type

ANSINo.1)

Overfluxing

Synchronism check

Synchronising

Undervoltage

U/f protectionSpannungs-/Frequenz-Schutz

Line breaker failure

Overvoltage

Autoreclose

Frequency relay

24

25

27

27/59/81

50BF

59

79

81

–

■

–

–

–

–

–

■

–

–

–

■

–

–

–

–

–

–

–

–

–

–

–

■

–

–

–

■

–

–

■

■

–

■

–

■

–

–

–

–

–

■

–

–

–

1) ANSI/IEEC C 37.2: IEEE Standard Electrical Power System DeviceFunction Numbers

Circuit-breaker52


2829


ANSINo.1)

51

51, 37

49

46

87

59

27

64S

64S

81o

81u

32

40

64R

24

21

78

87N

1) ANSI/IEEE C 37.2: IEEE Standard Electrical Power System DeviceFunction Numbers

■

■ 3)

■

■

■

■

■

■

■

■ 7)

■ 4)

■ 4)

■

■

■

■

■ 3)

4

2

Function

Overcurrent

Overcurrent/Undercurrent

Thermal overload

Load unbalance

Differential protection

Overvoltage

Undervoltage

U < with frequency evaluation

Direct voltage

Stator

earth-fault protection < 90 %

Stator

earth-fault protection 100 %

Interturn fault protection

Overfrequency

Underfrequency

Reverse power

Forward power2)

Underexcitation (field failure)

protection

Rotor

earth-fault protection

Overexcitation

protection

Impedance protection

Out-of-step protection

Restricted earth-faultprotection

Trip control inputs

Trip circuit monitoring

Relay

7UM

511

I>, t(+U<)

IE>, t

I>>, t

I ><, t

I2t

I2In>, t

(I2lIn)2 t

∆IG>

∆IT>

∆Ig>

U>, t

U>>, t

U>, t

t = f(U<)

U(f)<, t

U=><, t

UE >,t

UE + IE>,t

RE <,t

UW >,t

f>

f<

(–P)>, t

(+P)>, t

ϑ>, t

ϑ1 + Ue>, t

RE<, t(fN)

RE<, t(1Hz)

IE>, t(fN)

U/f >, t

(U/f)2 t

Z<, t

ϑ(Z) >, n

∆IE

t, trip

7UM

512

■

■

■

■

■

■

■

■

■

■

■ 5)

■ 5)

■ 8)

■ 8)

■

4

2

7UM

515

■

■

■

■

■

■

■ 4)

■ 4)

■

■

■

4

2

7UM

516

■

■

■

■

■

■

■

4

2


2) For special applications

3) I> sensitive stage,suitable for rotor or statorearth-fault protection

4) Altogether 4 frequency stages,to be used as either f> or f<

5) Altogether 4 frequency stages,to be used as either f> or f<

6) Tank protection

7) Evaluation of displacementvoltage

8) 1 stage

8.4 Typical ProtectionSchemesRadial systems

Notes on Fig. 8/15:1) ANSI no. 79 only for reclosure with

overhead lines.

2) Negative sequence o/c protection46 as back-up protection againstasymmetrical faults.

General hints:C The relay (D) with the largest dis-

tance from the infeed point getsthe shortest operating time. Relaysfurther upstream have to be time-graded against the next down-stream relay in steps of about 0.3seconds.

C Dependent curves can be selectedaccording to the following criteria:

C Definite time: Source impedance is large compa-red to the line impedance, i.e.small current variation betweennear and far end faults

C Inverse time: Longer lines, where the fault cur-rent is much less at the end of theline than at the local end.

C Highly or extremely inverse time: Lines where the line impedance islarge compared to the sourceimpedance (high difference forclose-in and remote faults) or lines,where coordination with fuses orreclosers is necessary. Steepercharacteristics also provide higherstability on service restoration (coldload pickup and transformer inrushcurrents).

Ring mains

General hints on Fig. 8/16C Operating time of overcurrent re-

lays to be coordinated with down-stream fuses of load transformers.(Highly inverse time characteristic

with about 0.2 s grading-time delayto be preferred)

C Thermal overload protection for thecables (option)

C Negative sequence o/c protection46 as sensitive protection againstunsymmetrical faults (option)

8

51N51 46 79

51N51 46

51N51 46

Infeed

Furtherfeeders

I>, t IE>, t I2>, t ARC

2) 1)

I>, t IE>, t I2>, t

A

B

C

Load

Load Load

D I>, t IE>, t I2>, t

7SJ60

7SJ60

7SJ60

Transformerprotection,see Fig. 8/20

or 7SJ4 (46 not fittedc.t. powered versionavailable

Fig. 8/15 Protection scheme with overcurrent-time protection

51N51 46 49

I>, t IE>, t I2>, t52

5252

51N51 46 49

I>, t IE>, t I2>, t ϑ>52ϑ>

Infeed

7SJ60

Transformerprotection,see Fig. 8/22

7SJ60 or 7SJ4 (46 and 49not fitted c.t. poweredversion available)

Fig. 8/16 Protection circuit for ring circuit

Distribution feeder with reclosers

General hints on Fig. 8/17:C The feeder relay operating charac-

teristics, delay times and autoreclo-sure cycles must be carefully coor-dinated with downstream reclo-sers, switch disconnectors andfuses. The instantaneous zone50/50N is normally set to reach outto the first main feeder sectionali-sing point. It has to ensure fastclearing of close-in faults and pre-vent blowing of fuses in this area(“fuse saving”). Fast autoreclosureis initiated in this case. Furthertime-delayed tripping and reclosuresteps (normally 2 or 3) have to begraded against the recloser.

C The o/c relay should automaticallyswitch over to less sensitive char-acteristics after longer load inter-ruption times to enable overridingof subsequent cold load pickup andtransformer inrush currents.

Parallel feeder circuit

General hints on Fig. 8/18:C This circuit is preferably used for

the interruption-free supply of im-portant consumers without signifi-cant backfeed.

C The directional o/c protection67/67N trips instantaneously forfaults on the protected line. This al-lows the saving of one time-grad-ing interval for the o/c relays at theinfeed.

C The o/c relay functions 51/51N haveeach to be time-graded against therelays located upstream.

3031


52

50/51

50N/51N 46

79

52

7SJ60

Infeed

I>>,I>, t

IE>>,IE>, t

I2>, t

Autoreclose

Recloser

Sectionalisers

Fuses

Furtherfeeders

52

51N51 49 46 7SJ60

7SJ6267N67 51 51N

52

52

52

52

52

52

52

52

Infeed

Protectionsame asline or cable 1

I>, t IE>, t I2>, tϑ>

Load

OH line orcable 1

OH line orcable 2

Load

Fig. 8/17 Protection scheme for distribution feeder

Fig. 8/18 Protection scheme for parallel feeder circuit

Cables or short overhead lineswith infeed from both ends

Notes on Fig. 8/19:1) Autoreclosure only with overhead

lines

2) Overload protection only with ca-bles

3) Differential protection options:C Type 7SD511/12 with direct fibre-

optic connection up to about 20 km(approx. 12.5 miles) or via a 64kbit/s channel of a general purposePCM connection (optical fibre,microwave)

C Type 7SD600 with 2-wire pilot ca-bles up to about 10 km (approx.6.25 miles)

C Type 7SD502 with 2-wire pilot ca-bles up to about 20 km

C Type 7SD503 with 3-wire pilot ca-bles up to about 10 km.

4) Functions 49 and 79 only with re-lays of type 7SD5**. 7SD600 is acost-effective solution where onlythe function 87L is required (exter-nal 4AM4930 current summationtransformer to be ordered sepa-rately).

Small transformer infeed

General hints on Fig. 8/20:C Earth faults on the secondary side

are detected by current relay 51Gwhich, however, has to be time-graded against downstream feederprotection relays. The restrictedearth-fault relay 87N may additio-nally be used to achieve fast clear-ance of earth faults in the second-ary transformer winding. Relay

7VH80 is of the high-impedancetype and requires class X currenttransformers with similar transfor-mation ratio.

C Primary breaker and relay may bereplaced by fuses.

8

52

52

52

51N/51N 87L

79

49

1)

2)

52

51N/51N 87L

79

49

1)

2)

3)

52

52

52

52 52 52 52

4)

4)

7SD600or7SD5**

7SD600or7SD5**

Load

Infeed

Sameprotectionfor parallel line,if applicable

Line orcable

Backfeed

7SJ60

7SJ60

5150 50N 49

7SJ60

52

52

46

63

87N

51G

7SJ60

RN

52

HV infeed

I>> I>, t IE> ϑ>

Load

Optional resistor orreactor

I2>, t

I>>

IE>7VH80

o/c relay

Distribution bus

Fuse

Load

Fig. 8/19 Schutzkonzept mit Differenzialschutz

Fig. 8/20 Schutzkonzept für kleine Transformatoren

Dual infeed with singletransformer

Notes on Fig. 8/21:1) Line current transformers are to be

connected to separate stabilisinginputs of the differential relay 87Tin order to assure stability in caseof line through-fault currents.

2) Relay 7UT513 provides numericalratio and vector group adaptation.Matching transformers, as usedwith traditional relays, are there-fore no longer applicable.

Parallel incoming trans-former infeed

Note on Fig. 8/22:1) The directional functions 67 and

67N do not apply for cases wherethe transformers are equippedwith transformer differential relays87T.

3233


52 52

46

51 51N50

49

63

7SJ60

7SJ60

52

52 52 52

87T87N

Protection line 1same as line 2

Load

I>> IE>

Protection line 221/21N or 87L + 51 + optionally 67/67N

I>> I>, t IE>, t

ϑ>I2>

7SJ60 or7SJ61

Loadbus

51G

51N51

7UT61or7UT513

5150 51N 49 46

52

52

51G

52

52

52 52

63

51N51

52

67 67N

I>, t IE>, t IE>

7SJ62

I>> I>, t IE>, t ϑ> I2>, t

Load

HV infeed 1

7SJ60

Load

HV infeed 27SJ60 or7SJ61

Protectionsame asinfeed 1

I>

1)

Load

Loadbus

IE>, t

Fig. 8/22 Protection scheme for transformers connected in parallel

Fig. 8/21 Transformer protection scheme

Arbeitsplatz1

1) und 2) fehlen

Small and medium-sizedmotors < 1 MW

a) With effective or low-resistance-grounded infeed (IIE ≥ IIN Motor)

General hint on Fig. 8/23:Applicable to low-voltage motors andhigh-voltage motors with low-resist-ance earthed infeed (IE ≥ IN Motor).

b) With high-resistance-groundedinfeed (IIE ≤ IIN Motor)

Notes on Fig. 8/24:1) Window-type zero-sequence cur-

rent transformer.

2) Sensitive directional ground-faultprotection 67N only applicablewith infeed from isolated or Peter-son-coil-grounded network. (For dimensioning of the sensitivedirectional earth-fault protection,see also application circuit No. 24)

3) If 67G is not applicable, relay7SJ602 can be applied.

Large HV motors > 1 MW

Notes on Fig. 8/25:1) Window-type zero-sequence cur-

rent transformer.

2) Sensitive directional earth-faultprotection 67N only applicablewith infeed from isolated orPeterson-coil-grounded network.

3) This function is only needed formotors where the run-up time islonger than the safe stall time tE.According to IEC 79-7, tE is thetime needed to heat up AC wind-ings, when carrying the startingcurrent IA, from the temperaturereached in rated service and atmaximum ambient temperature tothe limiting temperature.

8

Fig. 8/23 Typical protection for small motors

Fig. 8/25 Typical protection scheme for large motors

49CR

52

4951N50 7SJ60

M

I>> Lockedrotor

IE> ϑ>

46

I2>

49CR

52

507SJ62or7SJ551

51G 67G

M

Lockedrotor

I>>

IE>

ϑ> I2>

4649

I<

37

2)7XR961)60/1A

3)

49CR

52

50

51G 67G

7SJ62 or7SJ551

49T

Speedswitch M

87M

37

4)

Lockedrotor

I>>

IE>

ϑ>I2>

4649

U<

27

2)7XR961)60/1A

Startupsupervision

I<Optional

RTD’soptional

3)

3)

5) 6)

7UT612or7UT512

Fig. 8/24 Typical protection scheme for medium-sized motors

A separate speed switch is used tomonitor actual starting of the motor.The motor breaker is tripped if themotor does not reach speed in thepreset time. The speed switch is partof the motor delivery itself.

4) Pt100, Ni100, Ni120

5) 49T only available with relay type7SJ5

6) High-impedance relay 7VH83 maybe used instead of 7UT12 if differ-ent class X current transformersare provided at the terminal andstar-point side of the motor wind-ing.

Smallest generators < 500 kW

Note on Fig. 8/26 and 8/27:1) If a window-type zero-sequence

current transformer is provided forsensitive earth-fault protection, re-lay 7SJ602 with separate earthcurrent input can be used (similarto Fig. 8/24).

Small generator, standardrating 1 MW

Note on Fig. 8/28:1) Two current transformers in

V-connection are sufficient.

3435


Fig. 8/26 Typical protection scheme for smallest generators with solidly earthed neutral

Fig. 8/27 Typical protection scheme for smallest generator with resistance-earthed neutral

Fig. 8/28 Typical protection scheme for small generators

7SJ60G

46 4951

51N

I>, IE>, t

MS

I2> ϑ>

G146 49

5151N

7SJ60

RN =VN

√3 • (0.5 to 1) • Irated

1)

I>, IE>, t I2> ϑ>

MS

Generator 2

52

7UM61

G

51

51G

64R

PI>, t

IE>, t

I2>

4632

L.O.F

40

1)

Field

Small generators > 1 MW

Notes on Fig. 8/29:1) Functions 81 and 59 only required

where drives can assume excessspeed and voltage controller maypermit rise of output voltage aboveupper threshold.

2) Differential relaying options:

C 7UT612: Low-impedance differ-ential protection 87

C 7UT613: Low-impedance differ-ential 87 with integral restrictedearth-fault protection 87G

C 7VH83: High-impedance differen-tial protection 87 (requires classX current transformers)

3) 7SJ60 used as voltage-controlledo/c protection.

Function 27 of 7UM61 is used toswitch over to a second, more sensi-tive setting group.

Large generator > 1 MWfeeding into a network withisolated neutral

General hints:The setting range of the directionalearth-fault protection 67G in the7UM61 relay is 2–1000 mA.

Dependent on the current trans-former accuracy, a certain minimumsetting is required to avoid fault oper-ation on load or transient rush cur-rents.

8

Table 8/10 Minimum relay setting

52

7UM61

G

51G

64R

P

87

87G

51

27

81

59

51 32 46 40 49

7SJ60

MS

I

RE field<

I>, t

2)

IG

O/Cv.c.

I2> L.O.F. ϑ>

1)

1)

U<

U>

f>

IE>, t

Field

3)

Fig. 8/29 Protection scheme for small generators

Relay ground current input Minimum relay setting: Comments:connected to:

Core-balance c.t. 60/1 A:1 single CT 2 mA2 parallel CTs 5 mA3 parallel CTs 8 mA4 parallel CTs 12 mA

Three-pase CTs in 1A CT: approx. 50 mA In general not residual (Holmgreen) 5A CT: approx. 200 mA suitable for sensi-connection tive earth-fault

protection

Three-phase CTs in residual 2 – 3 ‰ of secondary 1A CTs are not(Holmgreen) connection with rated CT current In SEC: recommended inspecial factory calibration this caseto minimum residual false 10–15 mA with 5A CTscurrent (≤ 2 mA)

Busbar protection by o/crelays with reverse inter-locking

General hint on Fig. 8/30Applicable to distribution busbarswithout substantial (<0.25 x IN)backfeed from the outgoing feeders.

High-impedance busbarprotection

General hints:C Normally used with single busbar

and 11/2 circuit-breaker schemes

C Requires separate class X currenttransformer cores. All currenttransformers must have the sametransformation ratio.

Note:A varistor is normally applied acrossthe relay input terminals to limit thevoltage to a safety value below theinsulation voltage of the secondarycircuits.

Low-impendance bus zoneprotection

O.t. also circuits may be connected inseries with feeder protection selesAdjusts different o.t. ratios withincertain limits.

3637


Fig. 8/30 Busbar protection with reverse interlocking

87BB

87S.V.

5151N

Transformerprotection

7VH83

52 52

G

Feederprotection

Feederprotection

52

G

Feederprotection

86Alarm

Load

1)

or 7SS60

52

52

5050N

5151N

52

5050N

5151N

5050N

5151N

52

5050N

5151N

7SJ60

7SJ60

7SJ60 7SJ60

t0 = 50 ms

I> I>, t I> I>, t

I>, t0 I>, t

I> I>, t

Infeed

Reverse interlocking

Fig. 8/31 High-impedance busbar protection

totally integrated power protection

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