Application of Australian Standards to HV Switchgear Routine Testing

Gabriel OjeahDirector, Principal Engineer,

Gadian Electrical Engineering Services Pty Ltd

High Voltage ConferencePerth 2015

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Presentation Outline

Purpose and Legal Status of Standards Basic Functions of Electrical Switchgear Main Components of Typical Switchgear Assembly Applicable Standards for HV Switchgear Routine Tests HV Switchgear Routine Tests Under AS 62271.200 Switchgear components not specifically covered by AS

62271.200 Summary Quiz

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Purpose and Legal Status of Standards

Standards exist for various reasons including;• Specifying minimum design requirements• Specifying legislative requirements• Providing purchasing specifications• Providing technical conditions for contracts• Providing guidance

Legal Status of Standards• Own their own, no legal status and no requirement for

compliance• When called up in government legislation, they become

mandatory and can be subject to the scrutiny of the courts

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Basic Functions of Electrical Switchgear

Basic functions of a switchgear assembly include;• Control: Functional switching and emergency

switching• Protection: Fast isolation of faulted circuits• Isolation: Secure physical isolation of downstream

circuits for maintenance or other purposes

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Main Components of Typical Switchgear Assembly

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Main Components of Typical Switchgear Assembly

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Applicable Standards for HV Switchgear Routine Tests Australian Standard 2067-2014 - Substations and High

Voltage Installations Exceeding 1 kV ac• Still in Draft as at August 2015• “factory-built, type-tested high voltage switchgear shall be

manufactured and tested in accordance with relevant standards such as AS 62271.1, AS 62271.200, AS 62271.201 and AS 62271.203”

AS 62271.200 - High-voltage switchgear and controlgear Part 200: A.C. metal-enclosed switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV• Calls up AS 62271.1 frequently

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Applicable Standards for HV Switchgear Routine Tests

Standards for the main components of the switchgear to be considered as well;• Circuit breakers• Voltage transformers• Current transformers• Disconnectors and earth switches• Contactors

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HV Switchgear Routine Tests Under AS 62271.200

Dielectric test on the main circuit (AS 62271.200 subclause 7.1) Test on auxiliary and control circuits (AS 62271.200 subclause

7.2) Measurement of the resistance of the main circuit (AS 62271.200

subclause 7.3) Tightness Check (AS 62271.200 subclause 7.4) Design and Visual Checks (AS 62271.200 subclause 7.5) Partial Discharge Measurement (AS 62271.200 subclause 7.101)

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HV Switchgear Routine Tests Under AS 62271.200

Mechanical operation tests (AS 62271.200 subclause 7.102) Pressure tests of gas-filled compartments (AS 62271.200

subclause 7.103) Tests of auxiliary electrical, pneumatic and hydraulic devices (AS

62271.200 subclause 7.104) Tests after erection on site (AS 62271.200 subclause 7.105) Measurement of fluid condition after filling on site (AS 62271.200

subclause 7.106)

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Dielectric test on the main circuit (AS 62271.200 subclause 7.1) Dry short-duration power-frequency withstand voltage test With the circuit breakers (and disconnectors) closed, test voltage is

applied to one phase at a time with the other two phases earthed Test duration is 1 minute Test is deemed successful if no disruptive discharge occurs Rate of increase of test voltage, test duration and acceptance

criterion are specified in subclause 6.3.1 of IEC 60060-1 (High-voltage test techniques – Part 1: General definitions and test requirements

Requirements of the measurement system are specified in IEC 60060-2 (High-voltage test techniques – Part 2: Measuring systems)

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Dielectric test on the main circuit (AS 62271.200 subclause 7.1)

Power-Frequency Withstand Test Voltages Extracted from Table 1a of AS 62271.1

•Common values; phase-to-earth, and phase-to-phase•Across the isolating distance; where the clearance between open contacts is designed to meet the functional requirements for disconnectors (i.e. minimum clearance in air requirement)

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Test on auxiliary and control circuits (AS 62271.200 subclause 7.2)

Based on AS 62271.1 subclause 7.2 and consists of;• Inspection of auxiliary and control circuits for

verification of conformity with circuit diagrams and wiring diagrams

• Functional tests• Verification of protection against electric shock• Dielectric tests

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Test on auxiliary and control circuits (AS 62271.200 subclause 7.2)

Inspection of auxiliary and control circuits;• Physical damage• Quality of the individual components• Quality of the assembly• Mounting• Wiring termination• Adequacy of terminal strips• Adequacy of cable ducts

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Test on auxiliary and control circuits (AS 62271.200 subclause 7.2)

Inspection of auxiliary and control circuits;• Protection of wiring from heat & sharp objects, etc.• Verification of General Arrangement drawings

against the physical installation (device location, device details, etc.)

• Verification of Schematic drawings against the physical installation (continuity of the physical wiring, cable numbers, wire numbers, device details, types of contacts, functional correctness, etc.)

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Test on auxiliary and control circuits (AS 62271.200 subclause 7.2)

Functional tests• Verify that the auxiliary and control circuits function

properly in conjunction with the other parts of the switchgear

• Would include verification of voltage switching through individual MCBs, mechanical/electrical operation of switching devices, status of switching device auxiliary contacts, anti-pumping device operation, under-voltage relay operation, reduced voltage operation of circuit breaker open & close coils, etc.

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Test on auxiliary and control circuits (AS 62271.200 subclause 7.2) Verification of protection against electric shock;

• Done by visual inspection to ensure that metallic partitions and shutters provide protection against direct contact with the main circuit

• Also includes visual inspection to verify safe access to auxiliary and control equipment that can be touched during normal operation

• Where satisfactorily verification cannot be done through visual inspection, earthed metallic parts are checked for continuity to the earthing point (test at 30 A dc, result must be less than 0.1 )

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Test on auxiliary and control circuits (AS 62271.200 subclause 7.2) Dielectric tests;

• Power-frequency voltage withstand tests at 1 kV for 1 second

• Test between the auxiliary & control circuits connected together as a whole and the frame of the switchgear

• For parts that are normally insulated from each other, if practicable, also test between each part and the other parts connected together and connected to the switchgear frame

• Successful if no disruptive discharge occurs

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Measurement of the resistance of the main circuit (AS 62271.200 subclause 7.3) Unlike the tests we have considered so far, AS 62271.1 is

not applicable This test is subject to agreement between the

manufacturer and the user If the agreement is to use AS 62271.1 (subclause 7.3);

• Test current is between 50 A dc and rated current• Acceptance Criterion: 120% of the resistance

measured before the temperature-rise test during Type testing

• High resistance at lower current must be verified at a higher current as close as possible to the rated current

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Tightness Check (AS 62271.200 subclause 7.4)

Tightness check is based on leakage rate of the fluid (gas or liquid)

This test is based on AS 62271.1 subclause 7.4.• Methods for measuring or calculating the leakage

are provided

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Design and Visual Checks (AS 62271.200 subclause 7.5) Checked to verify compliance with the purchase/design

specifications A comprehensive checklist can be built from the

information in subclause 5 (Design and construction) of this Standard

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Partial Discharge Measurement (AS 62271.200 subclause 7.101) This test is subject to agreement between the

manufacturer and the user A test procedure is provided in Annex B of this

Standard

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Mechanical operation tests (AS 62271.200 subclause 7.102)

Switching devices are operated several times to;• ensure that they open and close correctly within the

specified limits of the supply voltage and pressure• ensure that the mechanical interlocks work properly

Withdrawable parts are inserted and removed several times to verify satisfactory operation

The specified number of operations for mechanical operations tests is 5

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Pressure tests of gas-filled compartments (AS 62271.200 subclause 7.103) Applicable only to gas-filled compartment rated above

50 kPa (relative pressure) Test for 1 min at 130% of the design pressure

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Tests of auxiliary electrical, pneumatic and hydraulic devices (AS 62271.200 subclause 7.104) Electrical, pneumatic and other interlocks together with

control devices that have a predetermined sequence of operation are tested;• five times in succession• at the most unfavourable limit (upper or lower) of the

auxiliary supply An example would be attempting to close a circuit

breaker with the close release coil disabled and making another attempt with the close release coil energised at a voltage just above the lower limit

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Tests of auxiliary electrical, pneumatic and hydraulic devices (AS 62271.200 subclause 7.104) This test differs from functional test because it is

conducted repeatedly under adverse conditions The test is considered to be satisfactory if the auxiliary

device;• Operates properly without adjustments between

repeated operations• Remains in good operating condition after the tests• The ease of operation is practically the same before

and after the tests

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Tests after erection on site (AS 62271.200 subclause 7.105) Test to check correct operation The following tests are required;

• Main circuit short-duration power-frequency withstand voltage test at 80 % of the values indicated in subclause 7.1

• Tightness tests as specified in subclause 7. 4• For gas-filled compartments which are filled onsite,

measurement of fluid condition as specified in subclause 7.106 is conducted after filling

The same operational tests conducted during the factory routine test would be beneficial

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Measurement of fluid condition after filling on site (AS 62271.200 subclause 7.106) Applicable to all fluid-filled compartments Condition (pressure, volume, etc.) of the fluid is

determined in order to verify compliance with the manufacturer's specification.

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Switchgear components not specifically covered by AS 62271.200 Circuit Breakers: AS 62271.100 (High-voltage switchgear

and controlgear Part 100: High-voltage alternating current circuit-breakers)

Disconnectors and Earth Switches: AS 62271.102 (High-voltage switchgear and controlgear Part 102: Alternating current disconnectors and earthing switches)

AS 60470 (High-voltage alternating current contactors and contactor-based motor starters)

Current Transformers: AS 60044.1 (Instrument transformers Part 1: Current transformers)

Voltage Transformers: AS 60044.2 (Instrument transformers Part 1: Inductive voltage transformers)

Protection Relays: Refer to system functional design specification and IEC 60255 series Standards

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Summary

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Quiz

How do we know whether a Standard is legally binding, i.e. called up by legislation?

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Quiz

Here in Australia, we often here the term “Medium Voltage” used when referring to switchgear and other electrical equipment. Which technically correct voltage range does this refer to?

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Quiz

For power-frequency voltage withstand tests after erection on site, AS 62271.200 calls for de-rating the test voltage to 80%. For subsequent routine tests throughout the life of the switchgear, is it always safe to continue testing at 80%?

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