type h-3 and hv-3 three phase directional relays ... · 41-226.2e type h-3 and hv-3 three phase...

41-226.2E Type H-3 and HV-3 Three Phase Directinal Relay

Fig. 1. Schematic - Top View of Polyphase Directional Unit. Fig. 2. Internal Schematic of the Type H-3 Relay in the FT-22Case.

Fig. 3. Internal Schematic of the Type HV-3 Relay in the FT-32Case

183A335

182A751

an air gap flux which interacts with the loop currentflux in the outer side of the loop and causes rotationof the shaft in the direction corresponding to thedirection of flow of the alternating current power.

One loop and its associated electromagnet make upone phase of the three-phase relay. With the 45°characteristic relay a delta voltage and a star currentare applied to each electromagnet, and proper phaseangle characteristics are obtained as follows. Theloop, which is considered as the secondary load of atransformer, has a much higher resistance than reac-tance, and the loop current lags the voltage appliedto the electromagnet by an angle of 10 to 15degrees. The air gap flux lags the applied current byabout 55 to 60 degrees because of the lag loopsaround the centerpole of the electromagnet. Thusmaximum torque occurs when the relay current leadsthe relay voltage by 45 degrees.

The 90° Connection is used on the relay to give therequired delta voltage and star current. With this con-nection one of the electromagnets will have “Aphase” (star) current and “BC” (delta) voltage which

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Type H-3 and HV-3 Three Phase Directinal Relay 41-226.2E

Fig. 4. Typical Phase Angle Curve for 45° Characteristic; 50 and60 Hertz, H-3 and HV-3 Relays - Balanced Three PhasePower Applied and No Spring Restraint.

Fig. 5. Typical Sensitivity Curve for 50 and 60 Hertz, H-3 andHV-3 Relays - at Maximum Torque Angle.

Curve 252147

for a system power factor of unity, lags the current by90°. Hence, with this connection and the above (45°)relay characteristics, maximum torque is obtainedwhen the system fault current is lagging its unitypower factor position by 45°.

With the watt characteristic relay a star current and astar voltage are applied to each electromagnet. Theair gap flux lags the applied current by about 10 to 15degrees because of the lag loops around the centerpole of the electromagnet. Thus maximum torqueoccurs when the relay current leads the relay voltageby about 0 degrees.

The instantaneous torque in each element of therelay is produced by the instantaneous products ofvoltage (loop current) and current (air gap flux) in theelectromagnet, which is a double frequency pulsatingtorque. The torques in the other two electromagnetsare also pulsating, but they are displaced 120degrees in time phase and when all three instanta-neous values are added, the result is a uniform non-pulsating torque.

Two moving contacts are mounted at right angles toeach other on the outer end of a leaf spring which inturn is mounted on Isolantite arm on the movingshaft. A stop bracket with a small cylinder partiallyfilled with tungsten powder is mounted behind eachmoving contact. When the moving contact strikesagainst the rigid fixed contact screw, the spring isdeflected for the necessary contact follow, afterwhich the stop strikes the moving contact. Thus, thefull torque of the relay is transmitted thru the contactsto maintain full contact pressure. The particles oftungsten powder in the small cylinder slide over eachother at the instant of impact and absorb the energyin the moving element. A flexible metal ribbon con-ducts current to the moving contacts.

The type H-3 relay is supplied with spring restraintwhich is adjusted to hold the contacts in the normalnon-trip position when the relay is deenergized. Thisprevents an incorrect directional indication by theelement under the condition of loss of load. However,the spring restraint may be adjusted to give a biastorque in either direction.

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Fig. 6. Typical Time - Current Curves of 50 and 60 Hertz, H-3Relay for three Phase Faults or Maximum Torque Angle.

Fig. 7. Typical Time - Current Curves of 50 and 60 Hertz HV-3Relay for Three Phase Faults at Maximum Torque Angle.

Voltage Restraint Unit

This element is supplied only in the type HV-3 relaysand consists of three electromagnets and loops simi-lar to those used on the directional element. Therestraining unit is mounted below the directional unitand the loops of the two units are fastened to a com-mon vertical shaft which operates the two contactsas described above. The outer coils of each electro-magnet have one delta voltage (E1) applied and thecenter coil has another delta voltage (E2) applied. Bymeans of the capacitor units in series with the outertwo coils, the phase angle characteristics of the elec-tromagnets are such that the torque of the element isproportional to:

V1• V2• sin Ø

where Ø is the angle between the two delta voltagesand is normally 60°.

If any one of the three delta voltages completely col-lapses during a fault, there is no torque on the elec-tromagnet, since the collapse of the third voltage

makes the sine of the angle between the voltageszero. If all three voltages decrease uniformly, thetorque varies as the square of their magnitude. Eachelectromagnet is connected to a different combina-tion of delta voltages so that a uniform restrainttorque and balanced burdens are obtained.

Restraint can be removed by opening any one supplylead to the restraint element. This applies singlephase to all three electromagnets and the sine of theangle becomes zero. At normal voltages 10.5amperes is required in each element at maximumtorque to overcome the restraint torque.

Contactor Switches

The dc contactor switch in the relay is a small sole-noid type switch. A cylindrical plunger with a silverdisc mounted on its lower end moves in the core ofthe solenoid. As the plunger travels upward, the discbridges three silver stationary contacts. The coil is inseries with the main contacts of the relay and withthe trip coil of the breaker. When the relay contactsclose, the coil becomes energized and closes the

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Fig. 8. Typical Time - Current Curves for 50 and 60 Hertz H-3and HV-3 Relays, Without Voltage Restraint for Phase toPhase Faults at Maximum Torque Angle - Full voltageCollapse on Faulted Phase, 86% Voltage on Un-faultedPhase.

Fig. 9. Typical Time - Current Curves for 50 and 60 Hertz TypeHV-3 Relay Without Voltage Restraint for Three PhaseFaults at Maximum Torque.

switch contacts. This shunts the main relay contacts,thereby relieving them of the duty of carrying trippingcurrent. These contacts remain closed until the tripcircuit is opened by the auxiliary switch on thebreaker.

Operation Indicator

The operation indicator is a small solenoid coil con-nected in the trip circuit. When the coil is energized, aspring-restrained armature releases the white targetwhich falls by gravity to indicate completion of the tripcircuit. The indicator is reset from outside of the caseby a push rod in the cover or cover stud.

Indicating Contactor Switch Unit (ICS ) –(HV-3 only)

The dc indicating contactor switch is a small clappertype device. A magnetic armature, to which leaf-spring mounted contacts are attached, is attracted tothe magnetic core upon energization of the switch.

When the switch closes, the moving contacts bridgetwo stationary contacts, completing the trip circuit.Also during this operation two fingers on the arma-ture deflect a spring located on the front of theswitch, which allows the operation indicator target todrop. The target is reset from the outside of the caseby a push rod located at the bottom of the cover.

The front spring, in addition to holding the target, pro-vides restraint for the armature and thus controls thepickup value of the switch.

3.0 CHARACTERISTICS

The types H-3 relays are provided with independentmake and break contacts. Two auxiliary contactorswitches - one in each contact circuit provide seal-incircuits for the main relay contact. The main contactswill close 30 amperes at 250 volts dc and the auxil-iary contactors will safely carry this current until thebreaker is tripped and the auxiliary “a” switch opens.

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The contactor switch has a minimum pickup of oneampere dc and a coil resistance of one ohm.

Typical 50 and 60 hertz phase angle characteristicsof the 45° characteristic relay are shown in figure 4.Maximum torque, in the contact closing direction,occurs when the line current lags the line-to-neutralvoltage by approximately 45 degrees, when usingthe 90° connection.

Typical 50 and 60 hertz sensitivity curves maximumtorque are shown in figure 5. The sensitivity of thetype HV-3 relay without voltage restraint is the sameas the type H-3 relay. The 60 hertz three phase mini-mum pick-up without spring restraint of the type H-3relay is 0.08 amperes at 115 volts, 0.15 ampere at 10volts, and 5.0 amperes at 1 volt. The single phaseminimum pick-up currents are approximately threetimes those for three phase. In the absence of suffi-cient operating current, the contacts may be heldeither open or closed by a toggle acting voltage - onlytorque. The effect of this torque is described in thesection under “Watt Characteristic Relay Adjust-ments.” It will be noted from the curves that the sen-sitivity of the type HV-3 relay with voltage restraint isdecreased only at voltages above 2 volts. The curvesalso show that 10 amperes 60 hertz are required at115 volts to overcome voltage restraint.

Typical time curves are shown in figures 6 to 9. Allcurves are for a contact spacing of .035 inch and atmaximum torque for 60 and 50 hertz relays and .070inch for 25 hertz relays.

Trip Circuit (HV-3 only)

The main contacts will safely close 30 amperes at250 volts dc and the seal-in contacts of the indicatingcontactor switch will safely carry this current longenough to trip a circuit breaker.

The indicating contactor switch has two taps that pro-vide a pickup setting 0.2 or 2 amperes. To changetaps requires connecting the lead located in front ofthe tap block to the desired setting by means of ascrew connection.

Trip Circuit Constant (HV-3 only)

Indicating Contactor Switch (ICS)

0.2 ampere tap 6.5 ohms dc resistance2.0 ampere tap 0.15 ohms dc resistance

4.0 INSTALLATION

The relays should be mounted on switchboard pan-els or their equivalent in a location free from dirt,moisture, excessive vibration, and heat. Mount therelay vertically by means of the four mounting holeson the flange for semi-flush mounting or by means ofthe rear mounting stud or studs for projection mount-ing. Either a mounting stud or the mounting screwsmay be utilized for grounding the relay. The electricalconnections may be made directly to the terminals bymeans of screws for steel panel mounting or to theterminal studs furnished with the relay for thick panelmounting. The terminal studs may be easily removedor inserted by locking two nuts on the stud and thenturning the proper nut with a wrench.

For detailed FT case information refer to I.L. 41-076.

5.0 ADJUSTMENTS AND MAINTENANCE

The proper adjustments to insure correct operation ofthis relay have been made at the factory and shouldnot be disturbed after receipt by the customer. If theadjustments have been changed, the relay takenapart for repairs, or if it is desired to check the adjust-ments at regular maintenance periods, the instruc-tions below should be followed.

All contacts should be cleaned periodically. A contactburnisher S#182A836H01 is recommended for thispurpose. The use of abrasive material for cleaningcontacts is not recommended, because of the dangerof embedding small particles in the face of the softsilver and thus impairing the contact.

Adjust the lower bearing so that both the top and bot-tom of the loops are equi-distant from their respectivemagnetic circuits. Energize the potential circuits ofthe relay until the loops reach operating temperature.About ten minutes at normal voltage is necessary toreach this condition. When the contact operatingtemperature is reached, adjust the upper bearing for1/64 inch clearance.

The loops of each element must be in line with thecenter of the middle leg of the magnetic circuit. Ifnecessary, this adjustment can be obtained by loos-ening the electromagnet mounting screws and mov-ing the whole electromagnet in the desired direction.All three elements must have the same relative posi-tion of loop and magnetic circuit.

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Type H-3 Relay

The polarity of the relay is checked as follows: Referto figure 2 and apply 115 volts and 5 amperes (inphase) to the corresponding voltage and current coilsin turn, with the terminals marked with polarity marksconnected together. Looking at the top of the relay,the moving element should rotate in a counter-clock-wise direction.

Adjust the back-up strip located in front of each mov-ing contact by bending so that it just touches the con-tact spring when the contacts are open. Adjust thesmall cylinder behind the moving contact to obtain.009 inch contact follow. This is done by advancingthe cylinder until it just touches the rear of the movingcontact spring, and then backing off 1 /2 turn.

45° Characteristic Relay Adjustments

Remove spring restraint by adjusting the springadjuster. Apply single-phase current of 50 amperes(momentarily) with polarities as shown on internalschematic diagram to the current coils which shouldbe connected in series. Each potential coil should beshort-circuited. When energized the relay movingelement will center itself due to the combined torquesproduced by the 50 amperes of current and thespring restraint. Readjust the spring adjuster until thecentering position of the moving element is exactlythe same for the condition of zero current or with 50amperes in the current coils. Under this condition thetorque produced by the spring at the centering posi-tion is zero and does not tend to “offset” or shift thecentering position due to the current. This final cen-tering position will be called the neutral position. Withthe moving element in the neutral position adjusteach stationary contact for .015 inch contact spacingand lock in this position for 60 and 50 hertz relaysand .035 inch for 25 hertz relays.

There are two adjustable stop screws located on theframe casting. These stops are used when the relayis supplied with two circuit closing contacts and per-form the same function as the stops on the movingcontact assembly.

Watt Characteristic Relay Adjustments

Remove spring restraint by adjusting the springadjuster. Apply single-phase potential of 67 volts withpolarities as shown on internal schematic diagram tothe potential coils which should be connected in par-allel. Each current coil should be open-circuited.

When the potential circuits are deenergized the mov-ing element will tend to be centered by the spring.When the potential circuits are energized the movingelement may move either to the right or to the left. Ifunder this condition the moving element moves thecontact to the right, the spring should be readjustedto move the deenergized spring centering position ofthe moving element to the left. If under this conditionthe moving element moves the contacts to the left,the spring should be readjusted to move the deener-gized spring centering position of the moving ele-ment to the right. Continue to shift the centeringposition of the spring until a small movement of thespring adjuster will cause the moving element tomove in one direction when the potential is appliedand a small movement in the other direction willcause the moving element to move in the oppositedirection. This final centering position will be calledthe neutral position. With the moving element in theneutral position adjust each stationary contact for.015 inch contact spacing and lock in this position for60 and 50 hertz relays and .035 inch for 25 hertzrelays.

Type HV-3 Relay

The tests outlined for the type H-3 45° characteristicrelay also apply to the HV-3 relay when the voltagerestraint circuit is not connected. To make a com-plete check on the type HV-3 relay with all circuitsconnected, involves three-phase test source, phaseshifter, potentiometers, and noninductive resistors forcontrolling the voltage and current to the relayrespectively. This test will permit checking of all thecharacteristics of the relay at the proper phase angle.This test procedure however is usually too compli-cated for routine field testing. The complete test maybe simplified for field testing by the following modifi-cations. Apply three phase restraining voltage to therestraining element and single phase to all threephases of the directional element. For the latter ele-ment the potential coils are all connected in paralleland the current coils are connected in series. With anon-inductive load, the relay will be operating about45° away from its maximum torque position and con-sequently current values to trip a given voltage willbe increased by about 30%. Since the combination ofthree-phase restraining torque and single-phaseoperating torques on all three elements producessome unbalanced torque in the moving element, it isrecommended that tests be made at a reduced volt-age (65 volts or less). With 65 volts applied to voltagerestraint elements, about 8 amperes is required atunity power factor to make the relay operate.

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To check the circuits thru the voltage restraint ele-ment, the relay should be energized at normal volt-age for about 10 minutes. The potential circuit of thedirectional element should then be opened. Thenopen the phase A potential to the voltage restraintunit and observe the torque produced on the movingelement, if any. Replace A lead and remove the Blead and again observe the torque. Repeat for the Clead and in all cases there should be no torque or avery slight torque present. Any defects in the coils orcapacitors of the voltage restraint circuits will bemade apparent by the presence of excessive torqueduring this test.

Contactor Switch

Adjust the stationary core of the switch for a clear-ance between the stationary core and the movingcore when the switch is picked up. This can be mostconveniently done by turning the relay upside-down.Screw up the core screw until the moving core startsrotating. Now, back off the core screw until the mov-ing core stops rotating. This indicates the point wherethe play in the moving contact assembly is taken up,and where the moving core just separates from thestationary core screw. Back off the stationary corescrew one turn beyond this point and lock in place.This prevents the moving core from striking andsticking to the stationary core because of residualmagnetism. Adjust the contact clearance for 3/32inch by means of the two small nuts on either side ofthe Micarta disc. The switch should pick up at 1ampere dc. Test for sticking and after 30 amperes dchave been passed thru the coil. The coil resistance isapproximately 1.0 ohm. For system schematic289B077, the ratings of the contactor switch areshown on the drawing.

Operation Indicator

Adjust the indicator to operate at 1.0 ampere dcgradually applied by loosening the two screws on theunder side of the assembly, and moving the bracketforward or backward. If the two helical springs whichreset the armature are replaced by new springs, theyshould be weakened slightly by stretching to obtainthe 1 ampere calibration. The coil resistance isapproximately 0.16 ohm. For system schematic289B077, the ratings of the operation indicator areshown on the drawing.

Indicating Contactor Switch (ICS) - (HV-3 only)

Close the main relay contacts and pass sufficient dccurrent through the trip circuit to close the contacts ofthe ICS. This value of current should not be greaterthan the particular ICS tap setting being used. Theindicator target should drop freely.

6.0 RENEWAL PARTS

Repair work can be done most satisfactorily at thefactory. However, interchangeable parts can be fur-nished to the customers who are equipped for doingrepair work. When ordering parts, always give thecomplete nameplate data.

7.0 ENERGY REQUIREMENTS

The burdens and constants of the relays are as fol-lows per phase:

8


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type h-3 and hv-3 three phase directional relays ... · 41-226.2e type h-3 and hv-3 three phase...

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