GE GEK-45404F User Manual

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GEK-45404F

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GE Power Management

INSTRUCTIONS

OVERVOLTAGE RELAYS

TYPES IAV, 51D

52C

D K

GE Power Management

205 Great Valley Parkway Malvern, PA 19355, USA

GEK-45404

DESCRIPTION................................................................................................................................................... 3

APPLICATION................................................................................................................................................... 4

RATINGS............................................................................................................................................................ 5

BURDENS.......................................................................................................................................................... 6

OPERATING CHARACTERISTICS................................................................................................................. 8

CONSTRUCTION.............................................................................................................................................. 9

RECEIVING, HANDLING, AND STORAGE ................................................................................................ 10

RECEIVING.................................................................................................................................................. 10

HANDLING.................................................................................................................................................. 10

STORAGE..................................................................................................................................................... 10

ACCEPTANCE TESTS.................................................................................................................................... 10

VISUAL INSPECTION ................................................................................................................................10

MECHANICAL INSPECTION..................................................................................................................... 11

ELECTRICAL TESTS.................................................................................................................................. 12

Drawout Relays - General.......................................................................................................................... 12

Power Requirements - General.................................................................................................................. 12

Pickup-voltage Test ................................................................................................................................... 12

Time-voltage Test...................................................................................................................................... 12

INSTALLATION.............................................................................................................................................. 13

INSPECTION................................................................................................................................................ 13

LOCATION................................................................................................................................................... 13

MOUNTING ................................................................................................................................................. 13

CONNECTIONS........................................................................................................................................... 13

GROUND CONNECTIONS......................................................................................................................... 13

OPERATION.................................................................................................................................................... 13

ADJUSTMENTS........................................................................................................................................... 14

Target and Seal-in Unit.............................................................................................................................. 14

Voltage Setting .......................................................................................................................................... 14

Time Setting............................................................................................................................................... 15

PERIODIC CHECKS AND ROUTINE MAINTENANCE.............................................................................. 15

MAINTENANCE.............................................................................................................................................. 15

DISK AND BEARINGS ............................................................................................................................... 15

CONTACT CLEANING............................................................................................................................... 16

SERVICING...................................................................................................................................................... 16

RENEWAL PARTS.......................................................................................................................................... 16

LIST OF ILLUSTRATIONS ............................................................................................................................ 17

Cover Photo(8043180)

These instructions do not purport to cover all details or variations in equipment nor provid e for every possible

contingency to be met in connection with installation, operation or maintenance. Should further information be desired or should particular problems arise which are not covered sufficiently for t h e purchaser's purposes, the matter should be referred to the General Electric Company.

To the extent required the products described herein meet applicable ANSI, IEEE and NEMA standards; but no

such assurance is given with respect to local codes and ordinances because they vary greatly.

OVERVOLTAGE RELAYS

TYPES IAV51D, IAV51K, IAV52C, IAV52D, IAV52K

GEK-45404

DESCRIPTION

These are single-phase, sensitive overvoltage relays of the induction disk construction. They are equipped with a time dial so as to provide adj ustable time delay i n their operation. The relays are principally applicab le for sensitive overvoltage ground detection for high-impedance grounded generators or for ungrounded power systems. The differences among the four rel ays are as indicated in Table A below. Each relay is mounted in a standard size S1 drawout case and the outline and panel drillings are shown in Figs. 14 and 15; Fig. 13 shows the outline for an external capacitor when used. The internal connections of the relays are indicated in the table. Each relay contains a target seal-in unit that is used to protect the relay m ain contact s and control spring from damage due to breaker-trip current.

TABLE A

CONTINUOUS

RATING**

(VOLTS)

IAV51D 115 10-40

199 16-64 YES 1NO 1

345 28-112 IAV51K 67 5.4-20 YES 1NO 2 IAV52C 115 9.2

199 16 NO 2NO* 3

345 28 IAV52D 199 16-64 YES 2NO* 4 IAV52K 67 5.4-20 YES 2NO* 5

* The two normally-open contacts have a common connection; refer to the internal connections of

the relay.

** All relays have a 360 volt 10 second rating.

PICKUP

RANGE,

VOLTS

TAPS CONTACTS

INTERNAL

CONNECTIONS

FIGURE

GEK-45404

APPLICATION

These are single-phase, sensitive, time-delay overvoltage relays. They are princip ally a pplicabl e for sensitive overvoltage ground detection for high-impedance grounded generators or for ungrounded power systems. These relays all have a capacitor in series with the operating coil. For the IAV51K and IAV52K relays, this capacitor is external to the relay because o f its large size. The effect of the capacitor is to tune the relay c oil circuit so that the relay pickup on third harmonic (180Hz) voltage is approximately eight times the relay pi ckup at 60 Hz. Thi s is particularly important in overvoltage ground detection for generators, since they produce a large third- harmonic component of voltage during normal operation.

The external connection diagram for the IAV51K or the IAV52K relay for sensitive generator ground detection is shown in Fig. 8. This is a typical protection scheme for a unit generator transformer using a distribution transformer connected in the neutral with a resistor across the transformer secondary. The IAV51K/52K relays are usually us ed for thi s application because they p rovide the very s ens itive 5.4 volt pickup rating. This enables the relay to detect a ground fault within a few percent of the wi nding from the neutral. Since the power transformer and the station service transformer in a unit generator transformer scheme are both connected in delta on the generator side, coordination with other protection is virtually unnecessary and the ground relay u sed can be very sensitive. Some time delay in relay operation is usually us ed to coordinate with fuses protecting against faults on the secondary side of potential transformers that are normally connected to the generator terminals. The usual practice is to use these relays to trip the generator breaker and shut down the machine. If the relay is used only t o sound an alarm when a ground fault is detected, the application should be reviewed. It may be necessary to add another relay to provide ground protection with good sensitivity simultaneously with a high continuous-voltage rating.

The resistor, shown in Fig. 8 connected across the broken delta secondary of the PT's, or alternatively connected in series in the primary neutral connection, is usually required to prevent the occurrence of ferro-resonance. Thi s phenomenon could occur due to the int eraction of the PT inductance with the distributed capacitance-to-ground of the primary power system.

The external connection diagram for the IAV51D, 52D, or the IAV52C relay for ground-fault detection on an ungrounded power system is shown in Fig. 9. The relay operates to detect the first ground fault that occurs on the system, connections so that it can be removed before a second ground occurs, causing a double phase-to-ground fault, which requires a service interruption. Since

the relay ma y b e applied merely to sound an alarm in this application, it is necessary that it be continuously rated for the full broken-delta voltage expected for a single phase-to-ground fault located right at the potential transformers, or some automatic means must be employed to disconnect the relay from the voltage supply.

When this fault occurs it is equivalent to shorting out one phase of the pot ential transformer primary. The other two unfaulted phases of the PT primaries now have full phase-to-phase voltage applied and their corresponding dJelta secondaries will be supplying √ 3 times their normal rated voltage. The broken delta equivalent voltage will be these two voltages added in series at a 60o angle and the

GEK-45404

broken delta voltage will therefore be three times the normal delta phase-to-phase voltage with no fault.

RATINGS

The operating-circuit ratings available are shown in Table I. The operating coil will stand rated voltage continuously on any tap.

RELAY VOLTAGE RATINGS

60HZ 50HZ

IAV51D 115 115

199 199

345 345 IAV51K 67 67 IAV52C 115 115

199 199

345 345 IAV52D 199 IAV52K 67 67

The current-closing rating o f the contacts is 30 amperes for voltage not exceeding 250 volts. The current-carrying ratings are affected by t he selection of the tap on the seal-in coil, as indicated in Table II.

TABLE II

FUNCTION AMPERES

2-Amp Tap 0.2-Amp Tap

Tripping Duty Carry

Continuously

The 2-ampere tap has a DC resistance of 0.13 ohms and a 60 cycle impedance of 0.53 ohms, while the 0.2-ampere tap has a 7-ohm DC resistance and a 52-ohm 60 cycle impedance. The tap setting used on the seal-in element is determined by the current drawn by the trip coil.

The 0.2-ampere tap is for use with trip coils that operate on currents ranging from 0.2 up to 2.0 amperes at the minimum control voltage. If this tap is used with trip coils requiring more than two amperes, there is a possibility th a t the 7-ohm resistance will reduce the current to so low a v alue t hat the breaker will not be tripped.

The 2-ampere tap should be us ed with trip coils that take 2 amperes or more at minimum control voltage, provided the tripping current does not exceed 30 amperes at the maximum control voltage. If the tripping c urrent exceeds 30 amperes an auxiliary r e l a y s hould be used, the connections being

0.3

GEK-45404

such that the tripping current does not pass through the contacts of the target and seal-in coil of the

protective relay.

BURDENS

Burdens for the various relay types are give in Tables IIIA and B.

TABLE IIIA

60 - Cycle Burdens Rated Voltage

RELAY

TYPES

1AV51D 115 A(10) 31.4 0.33 10.2

IAV51D 199 A(16) 32.0 0.31 9.9 IAV52D B(24) 27.9 0.56 15.6

IAV51D 345 A(28) 41.5 0.37 15.5

IAV51K 67 A(5.4) 34.0 0.31 10.5 IAV52K B(7.5) 31.0 0.52 15.9

IAV52C 199 No Taps 32.0 0.31 9.9

1AV51D 115 A(10) 36.8 0.34 12.6

IAV51D 199 A(16) 25.4 0.28 7.0

VOLTAGE

RATING

115 No Taps 24.2 0.21 5.0

345 No Taps 41.5 0.37 15.5

TAP**SETTING VOLT-AMPS POWER

FACTOR

B(15) 27.2 0.57 15.6 C(25) 19.0 0.82 15.6 D(40) 12.3 0.93 11.4

C(40) 20.0 0.81 16.2 D(64) 13.2 0.92 12.2

B(42) 35.0 0.62 21.6 C(70) 23.9 0.85 20.3

D(112) 13.6 0.95 12.9

C(12.5) 23.1 0.77 17.7

D(20) 16.0 0.9 14.4

B(15) 30.8 0.62 19.0 C(25) 20.3 0.86 17.4 D(40) 12.7 0.95 12.0

B(24) 23.1 0.5 11.5 C(40) 17.8 0.74 13.3 D(64) 12.4 0.88 11.0

WATTS

TABLE IIIA (CONTINUED)

GEK-45404

50 - Cycle Burdens at Rated Voltages

RELAY

TYPES

IAV51D 345 A(28) 31.9 0.36 11.4

IAV51K 67 A(5.4) 28.8 0.29 8.4 IAV52K B(7.5) 26.6 0.45 12.1

IAV52C 199 No Taps 25.4 0.28 7.0

**Minimum pickup volts

VOLTAGE

RATING

115 No Taps 25.0 0.41 10.1

345 No Taps 31.9 0.36 11.4

TAP**SETTING VOLT-AMPS POWER

FACTOR

B(42) 28.3 0.56 15.8 C(70) 21.0 0.79 16.6

D(112) 12.8 0.93 11.9

C(12.5) 21.1 0.71 14.9

D(20) 16.0 0.86 13.7

TABLE IIIB

WATTS

60 - Cycle Burden at Rated Voltages RELAY TYPES 1AV51D 115 A(10) 0.46 0.99 0.46

IAV51D 199 A(16) 0.41 0.94 0.38 IAV52D B(24) 0.56 0.98 0.55

IAV51D 345 A(28) 0.48 0.86 0.41

IAV51K 67 A(5.4) 0.43 0.91 0.39 IAV52K B(7.5) 0.57 0.96 0.55

VOLTAGE RATINGS

TAP**SETTINGS VOLT-AMPS POWER

FACTOR

B(15) 0.62 1.0 0.62 C(25) 0.96 1.0 0.96 D(40) 1.48 1.0 1.48

C(40) 0.89 0.99 0.88 D(64) 1.38 1.0 1.37

B(42) 0.66 0.95 0.62 C(70) 1.02 0.98 1.01 D(112) 1.4 0.99 1.4

C(12.5) 0.92 0.98 0.91 D(20) 1.47 0.99 1.46

WATTS

115 No Taps 0.36 0.78 0.28

IAV52C 199 No Taps 0.41 0.94 0.38

345 No Taps 0.48 0.86 0.41

TABLE IIIB

GEK-45404

50 - Cycle Burden at Rated Voltages RELAY TYPES 1AV51D 115 A(10) 0.52 0.98 0.52

IAV51D 199 A(16) 0.32 0.85 0.27

IAV51D 345 A(28) 0.39 0.96 0.37

IAV51K 67 A(5.4) 0.38 0.91 0.34 IAV52K B(7.5) 0.52 0.95 0.5

IAV52C 199 No Taps 0.32 0.85 0.27

VOLTAGE RATINGS

115 No Taps 0.27 0.98 0.27

345 No Taps 0.39 0.96 0.37

TAP**SETTINGS VOLT-AMPS POWER

FACTOR

B(15) 0.67 0.99 0.67 C(25) 1.0 1.0 1.0 D(40) 1.52 1.0 1.52

B(24) 0.5 0.93 0.46 C(40) 0.83 0.97 0.81 D(64) 1.33 0.99 1.32

B(42) 0.58 0.98 0.57 C(70) 0.96 0.99 0.95 D(112) 1.35 1.0 1.35

C(12.5) 0.87 0.98 0.85 D(20) 1.42 0.99 1.41

WATTS

**Minimum pickup volts

OPERATING CHARACTERISTICS

The Type IAV51D relay is a low-pickup voltage relay normally u s e d for ground fault protection on

AC rotating machines. It has single-circuit closing contacts that close when the voltage increases to pickup value, as set on the tap block. The time delay in closing the contacts is determined by th e se tting of the time dial at the top of the shaft. The IAV51D has a capacitor and tapped resistor connected in series with the operating coil. The capacitor is added to tune the circuit, giving a low pickup voltage at rated frequency. At rated voltage the operating U magnet is highly saturated, increasing the impedance of the circuit, thus limiting the current to a s afe value. The taps on the resistor are connected to the tap block to provide a four-to-one range of pickup. As shown in the typical external connection diagram, Fig. 8, this relay is connected to the machine neu tral potential transformer through a closed contact on the auxiliary tr i pping r elay, hence is energized only w h e n a ground occurs. To obtain still-lower pickup than the normal calibration, it is permissible to insert an inverted potential transformer between the machine neutral transformer and the relay c oil circuit. The IAV51D has a seal-in element. Time curves are shown in Fig. 11.

The IAV51K relay is similar to the IAV51D except that it has an external capacitor. Time curves are shown in Fig. 11.

GEK-45404

The IAV52K relay is similar to the IAV51K except that it has two, instead of one, normally-open contacts.

The IAV52C is a low-pickup, time-overvoltage relay with two normally-open contacts. It has a sealin element. It has a capacitor connected in series with the operating coil but, unlike the IAV51D relay, it does not have a tapped resistor connected in series with the operating c oil. The time-voltage characteristics at the #1, #5, and #10 time-dial settings are the same as for the "A" taps of the IAV51/52D and K relays shown in Fig. 11.

CONSTRUCTION

These relays are the induction disk construction. The disk is actuated by a potential operating coil on a laminated U-magnet. The disk shaft carries the moving c ontact, which completes the trip or al arm circuit when it touches the stationary contact or contacts. The disk shaft is restrained by a spiral spring to give the proper contact-closing voltage, and its motion is retarded by per ma ne nt magnets acting on the disk to give the correct time delay.

There is a seal-in unit mounted to the left of the shaf t. This unit has its coil in series and its contacts in parallel with the main contacts, such that when the main contacts close, the seal-in unit picks up and seals in. When the seal-in unit picks up, it raises a target into view that latches up and remains exposed until released by pressing a button beneath the lower-left corner of the cover.

The case is suitable for either surface or semi-flush panel mounting and an assortment of hardware is provided for either mounting. The cover attaches to the case and also carries the reset mechanism when one is required. Two of the cover screws have provision for a sealing wire.

The case has studs or screw connections at the bottom for the external connections. The electrical connections between the relay units and the case studs are made through spring-backed contact fingers mounted in stationary, molded inner and outer blocks, between which nests a removable connecting plug that completes the circuits. The outer blocks, attached to the case, have the st uds for the external connections, and the inner blocks have the terminals for the internal connections.

The relay mechanism is mounted in a s teel framework called the cradle and is a complete unit, with all leads being terminated at the inner block. This cradle is held firmly i n the cas e by a latch at the top and the bottom and by a guide pin at the back of the case. The case and cradles are so contructed that the relay cannot be ins erted in the case upside down. The connecting p lug, besides making the electrical connections between the respective b locks of the cradle and case, also locks the latch in place. The cover, which is fastened to the case by thumbscrews, holds the connecting plug in place.

To draw out the cradle from a single-ended case, the cover must first be removed. Then the connecting plug can be drawn out. In so doing, the trip circuit is the first one opened, then the voltage circuits are opened. After the connecting plug has been removed, the lower latch can be released and the cradle easily drawn out. To replace the cradle, the reverse ord er should be fo llowed. The internal connections of the relays are shown in Figs. 3, 4, 5, 6, and 7.

GEK-45404

RECEIVING, HANDLING, AND STORAGE

RECEIVING

These relays, when not shipped as a part of a control panel, will be shipped in cartons designed to protect them against damage. Immediately upon receipt of the relay, an examination should be made for an y damage su stai ned during s hipment. If injury o r damage resulting from rough handling is evident, a damage claim should be filed at once with the transportation company a nd the nearest General Electric Sales Office should be notified promptly.

HANDLING

Reasonable care should be exercised in unpacki n g the relay in order that none of the p art s are in j u red nor the adjustments disturbed.

STORAGE

If the relays are not to be installed immediately, they should be st ored in their original cartons in a place that is free from moisture, dust, and metallic chips. Foreign matter collected on the outside of the case may find its way inside when the cover is removed and cause trouble in the operation of the relay.

ACCEPTANCE TESTS

Immediately upon receipt of the relay an inspection and acceptance test should be made to make sure that no damage has been sustained in shipment and that the relay calibrations have not been disturbed.

VISUAL INSPECTION

Check the nameplate stamping to make sure that the model number and rating of the relay agree with the requisition.

Remove the relay from its case and check that there are no broken or cracked molded parts or other signs of physical damage, and that all screws are tight.

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