TYPES

IJF51A, IJF51B, and IJF52A

INSTRUCTIONS GEI-19008F

FREQUENCY RELAYS

GENERAL fj ELECTRIC

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GEI-19008 Frequency Relays Type LJF

2

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Fig. I Type IJF Relay Re.oved From Case (Front Yiew)

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Fig. 2 Type IJF Relay Removed From Case {Rear Yiew)

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FREQUENCY TYPE

RELAYS IJF

INTRODUCTION These are relays of the induction disk type

intended for the protection of apparatus against the effects of overfrequency or underfrequency.

The Type IJF is an induction disk type relay mounted in a single unit drawout case. It has two shaded-pole U-magnet type driving elements acting on opposite sides of the disk. One of these, the operating element, is designed to drive the disk in the direction to close the left contacts, and the other, the restraining element to drive the disk in the contact-opening direction on relays having single­throw contacts and to close the right contacts on relays having double-throw contacts. The disk shaft is restrained by a spiral spring, the principal purpose of which is to hold the contacts open when the relay is de-energized. The motion of the disk is retarded by permanent magnets to give the correct time delay for closing the contacts.

There is a seal-in unit mounted to the left of the shaft on the Type IJF51A and IJF51:S relays. The Type IJF52A relay has a seal-in unit mounted on both sides of the shaft. This element has its coil in series and its contacts in parallel with the main contacts such that when the main contacts close, the seal-in element picks up and seals in. When the seal-in element picks up it raises a target into view which 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 semiflush 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. Each cover screw has provision for a sealing wire.

The case has studs or screw connections at both ends or at the bottom only 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 which completes the circuits. The outer blocks, attached to the case, have the studs for the external con-ne ct· o d th · bl k h th t 1 1 ns, an e 1nner oc s ave e ermma s for the internal connections.

The relay mechanism is mounted in a steel framework called the cradle and is a complete unit with all leads being terminated at the inner block. This cradle is held firmly in the case with a latch at the top and the bottom and by a guide pin at the

back of the case. The cases and cradles are so constructed that the relay cannot be inserted in the case upside down. The connecting plug, besides making the electrical connections between the re­spective blocks of the cradle and case, also lock the latch in place. The cover, which is fastened to the case by thumbscrews, holds the connecting plug in place.

To draw out the relay unit the cover is first removed, and the plug drawn out. Shorting bars are provided in the case to short the current transformer circuits. The latches are then released, and the relay unit can be easily drawn out. To replace the relay unit, the reverse order is followed.

A separate testing plug can be inserted in place of the connecting plug to test the relay in place on the panel either from its own source of current and voltage, or from other sources. Or, the relay unit can be drawn out and replaced by another which has been tested in the laboratory.

APPLICATION The Type IJF frequency relays are recom­

mended for protection of synchronous apparatus against overspeed or underspeed conditions caused by loss of load in the case of generators, or loss of supply power in the case of motor and condensers. The relays can be used to operate protective de­vices, or to sound an alarm whenever the frequency of the circuit varies by a predetermined amount above or below normal.

RATINGS These relays are available in frequency ratings

from 25 to 60 cycles and voltage ratings of 115 and 230 volts.

The current closing rating of the contacts is 30 amperes for voltages not exceeding 250 volts. The current-carrying ratings are affected by the selection of the tap on the seal-in coil as indicated in Table I.

TABLE I

Amperes, AC or DC Function

2-Amp Tap 0.2 Amp Tap

Tripping Duty 30 5

Carry Continuously 3 0.3

These instructions do not purport to cover all details or variations in equipment nor to provide 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 the purchaser's purposes, the matter s hould be referred to the General Electric Company.

To the extent required the products described herein meet applicable ANSI, IEEE and NEMA stand ards;

but no such assurance is given with respect to local codes and ordinances because they vary greatly.

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GEI-19008 Frequency Relays Type LJF

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Fig. 3 Type IJFSIA Relay, Voltage-Frequency Characteristics

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Fig. 5 Type IJF51B Relay, Voltage-Frequency Characteristics

* Indicates Revision

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CURVE NO.

1 RELAY ADJ. TO CLOSE

115 V - 61 CYCLES 115 V - 63 CYCLES 115 V - 65 CYCLES

1115 VOLTS CONSTANT IN All TESTS)

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Fig. � Type IJF51A Relay, Time-Frequency Characteristics

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The 2-ampere tap has a d-e resistance of 0.13 ohms and a 60 cycle impedance of 0. 53 ohms while the 0.2-ampere tap has a 7 ohm d-e 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 2 amperes, there is a possibility that the 7 -ohm resistance will reduce the current to so low a value that the breaker will not be tripped.

The 2-ampere tap should be used 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 current exceeds 30 amperes an auxiliary relay should be used, the connections being such that the tripping current does not pass through the contacts or the target and seal-in coils of the protective relay.

Frequency Relays Type IJF GEI-19008

BURDENS Burden data for the 55-60 cycle under frequency

relay and 60-65 cycles overfrequency relays are given in Table I at 115 volts 60 cycles.

Burdens listed are total burden of relay.

TABLE II

Relay Volt Power

Watts Amps Factor

IJF51A 8.7 .99 8.6 IJF51B 5.8 .98 5.7

Total burdens for the Type IJF52A relay at 115 volts are as follows:

TABLE III

Freq. Volt Power Watts

Amps Factor

25 6.3 .95 6 60 10.7 .89 9.5

RECEIVING, HANDLING AND STORAGE These relays, when not included 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 any damage sustained duFing shipment. If injury or damage resulting from rough handling is evident, a claim should be filed at once with the transportation company and the nearest Sales Office of the General Electric Company notified promptly.

Reasonable care should be exercised in un-

packing the relay in order that none of the parts are injured or the adjustments disturbed.

If the relays are not to be installed immediately, they should be stored 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.

INSTALLATION LOCATION

The location should be clean and dry, free from dust and excessive vibration, and well lighted to facilitate inspection and testing.

MOUNTING The relay should be mounted on a vertical

surface. The outline and panel diagram is shown in Fig. 12.

CONNECTIONS

Internal connection diagrams for the various relay types are shown in Fig. 7 to 9 inclusive. Typical wiring diagrams are given in Fig. 10 and 11.

One of the mounting studs or screws should be permanently grounded by a conductor not less than No. 12 B&S gage copper wire or its equivalent.

AUXILIARIES

When external capacitors, and in some cases resistors, are furnished with relays they are iden­tified by means of serial numbers. These numbers are of the form KX-1023 or OA-2155. The purpose of these numbers is to insure that each relay, when installed, will be provided with the same auxiliaries with which it was calibrated at the factory.

The reason for this precaution is to eliminate the variation in calibrations of the relays which would otherwise result from the variation in elec­trical properties of the auxiliaries.

ADJUS TMENTS TARGET AND SEAL-IN ELEMENT

For trip coils operating on currents ranging from 0.2 up to 2.0 amperes at the minimum control voltage, set the target and seal-in tap plug in the 0.2-ampere tap.

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GEI-19008 Frequency Relays Type IJF

For trip coils operating on currents ranging from 2 to 30 amperes at the minimum control voltage, place the tap plug in the 2-ampere tap.

The tap screw is the screw holding the right­hand stationary contact of the seal-in unit. To change the tap setting, first remove the connecting plug. Then take a screw from the left-hand stationary contact and place it in the desired tap. Next, remove the screw from the other tap, and place it in the left-hand contact. This procedure is necessary to prevent the right-hand stationary contact from getting out of adjustment. �crews should not be in both taps at the same time as pickup for d-e will be the higher tap value.

PICKUP

Pickup of the relays can be set for any frequency from minimum to maximum value.s inclusive as shown in Tables IV, V and VI.

To make the setting, apply the desired frequency at rated volts to the relay and adjust the resistor until the relay just picks up. The relay must be in the case for an accurate check of the operating point.

The relay is adjusted at the factory to have the pickup called for on the requisition or, if pickup is not specified, at the applicable nominal value shown in Tables IV, V and VI.

TABLE IV PICKUP CALIBRATION - IJF51A RELAY

RELAY RATED CALIBRATIO�-CYCLES TO CLOSE LEFT CONTACT M0DEL VULTS 1-REfLLJ_E�-lCY MlNI_"'l!}� "1AXI:1U�1 NOMlNAL

IJF51AlA 115 60HZ 61 65 63 IJF51A2A 115 60HZ 57 60 58 IJF51A3A 115 60HZ 51 55 53 IJF51A4A 115 60HZ 65 75 70 IJF51A5A 115 60HZ 45 49 47 IJF51A6A 115 60HZ 38 46 44 IJF51A7A 115 60HZ 58 62 60

IJF51A9A 115 150HZ 153 165 159 IJF51A10A 115 60HZ 60 70 65 IJF51A11A 115 60HZ I 55 65 61 IJF511\1 2A 115 140HZ 143 155 148 !JF51A13A 115 160HZ I 162 172 167

I I

TABLE V PICKUP CALIBRATION - IJF51B RELAY --

RELAY RATED CALIBRATI0N-CYCLES TO CLOSE LEFT CONTACT �100EL VOLTS FREQUENCY MINIMUM MAXIMUM NOMINAL

IJF51B1A 115 60HZ - - 45 IJF51B2A 115 60HZ 55 59 57 IJF5l133A 115 50HZ 45 49 47 IJF5184A 115 25HZ 22.5 24.5 23.5 IJF51B5A 115 60HZ 48 55 52

IJF5187A 220 50HZ 45 49 47 IJF5188A 115 60HZ 50 60 55

I ' '

TABLE VI PICKUP CALIBRATION - IJF52A RELAY

' ' RIGHT CONTACT CLOSES RELAY RATED CYCLES TO CLOSE LEFT CONTACT (CYCLES ABOVE LEFT) �DEL 0 VOLTS FREQUENCY MINIMUM MAXIMUM NOMINAL MINIMUM 0 MAXIMUM

IJF52A1A 115 25HZ 23 27 25 0.4 1.0 IJF52A2A 230 25HZ 23 27 25 0.4 1 .0 IJF52A3A 115 50HZ 49 51 50 0.8 2.0 IJF52A4A 115 60HZ 55 65 59 0.75 2.0

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TIME Operating time of the relay for a given condi­

tion is determined by the position of the drag magnet on its shell. Moving the drag magnet toward the disk shaft decrease pick-up time while moving it away from the disk shaft increases pick-up time.

Normally the time dial at the top of the disk shaft is readily adjustable with the fingers to give any time delay desired� within certain limits. It is

Frequency Relays Type LJF GEI-19008

usually difficult, in the field, to obtain odd fre­quencies for checking the pick-up time. As a precaution then against having the time dial ac­cidentally disturbed with no means available for resetting it, the time dial is locked in position at the factory to give the desired time. If it is desired to change the position of the time dial, this may be done by loosening the 2 screws through the frame just above the dial. Turning the dial counter-clockwise (top view) increases the contact travel and hence the time. Tighten l:he screws when the setting has been completed.

PRINCIPLES OF OPERATION The Type LJF51A relay is an overfrequency

relay having a single-circuit normally open contact which closes on overfrequency.

The Type LJF51B relay is an underfrequency relay having a single-circuit normally open contact which closes on underfrequency.

The Type LJF52A relay is an overfrequency and underfrequency relay having double throw contacts. The left contacts close on underfrequency and the right contacts close on overfrequency.

Discrimination between normal frequency and abnormal frequency is accomplished by the opposite variation in impedance with frequency of two cir­cuits, one circuit containing the coil of one U-magnet connected directly to the voltage supply and desig­nated as the inductive circuit, the other circuit containing the coil of the remaining U-magnet in series with an external capacftor connected to the same supply voltage and designated as the capacitive circuit, because the capacitive reactance predomi­nates at normal frequency.

In the underfrequency relay, the coil of the operating U-magnet composes the inductive circuit, and the coil of the restraining U-magnet in series with the capacitor composes the capacitive circuit.

At normal frequency the torque produced by the current through the capacitive circuit (restraining U-magnet) is greater than the torque produced by the current (operating U-magnet). A decrease in the frequency of the supply voltage is accompanied by a decrease in the impedance of the inductive circuit permitting an increase of the operating current, while the impedance of the capacitive cir­cuit increases, thereby reducing the restraining current. Thus as the supply frequency is decreased the operating U-magnet overcomes the restraining U-magnet and the relay operates.

The overfrequency relay differs fron1 the under­frequency relay in that the operating U-magnet coil is in the capacitive circuit and th£l restraining U­magnet coil forms the inductive circuit. Con­sequently, the torque of the inductive element is adjusted to preponderate at normal frequency.

Voltage-frequency characteristics are shown in Fig. 3 for the 60 cycle LJF overfrequency relays. Fig. 5 shows the voltage-frequency characteristics of the 60 cycle LJF undervoltage relay.

Time-frequency characteristics for the 60 cycle LJF overfrequency relays are shown in Fig. 4. Time frequency curves for the 60 cycle LJF underfrequency relays are shown in F.ig. 6.

MAINTENANCE The relays are adjusted at the factory and it is

advisable not to disturb the adjustments. If for any reason, they have been disturbed, the following points should be observed in restoring them:

DISK AND BEARINGS

The lower jewel may be tested for cracks by exploring its surface with the point of a fine needle. If it is necessary to replace the jewel a new pivot should be screwed into the bottom of the shaft at the same time. The jewel should be turned up until the disk is centered in the air gaps, after which it should be locked in this position by the set screw provided for this purpose. The upper bearing pin should next be adjusted until very little end play can be felt between the pin and the steel ball in the recess at the top of the shaft; about 0.015 inch is correct.

CONTACT CLEANING For cleaning fine silver contacts, a flexible

burnishing tool should be used. This consists of a flexible strip of metal with an etched roughened surface, resembling in effect a superfine file. The polishing action is so delicate that no scratches are left, yet corroded material will be removed rapidly and thoroughly. The flexibility of the tool insures the cleaning of the actual points of contact.

Fine silver contacts should not be cleaned with knives, files, or abrasive paper or cloth. Knives or files may leave scratches which increase arcing and deterioration of the contacts. Abrasive paper or cloth may leave minute particles of insulating abrasive material in the contacts and thus prevent closing.

The burnishing tool described is included in the standard relay tool kit obtainable from the factory.

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8

GEI-1900& Frequency Relays Type IJF

SEAL .. IN UNIT •

rr 2

OPERATJ NG COIL

*Fig. 7 (K-6306813 (2))

DOMINANT COIL AT LOW FREQ.

LOW FREQ. CONTACTS

. ...

+ I � I 6 8

"' RESTRAINING

COIL

��SHORT FINGER

Type IJF51A Relay, Internal Connections (Front View)

HIGH FREQ. CONTACTS

+ I � I � I � I 2 6 8 10

+ I 2

OPERATING co ll

RESTRAINjNG co ll

+ I 1 I 6 8

' • SHORT FINGER

Fig. 8 (K-6306616) Type IJF51B Relay, Internal Connections (Front View)

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�+<r-�"__, )h]�;;;:;:" f n l.-�

(a) OVE R-FREQUENCY >fLAYS TYPE IJF51A

EXTE RlfAl RES. (WHEN USED)

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8! •

-� (bj UNDER-FREQUENCY RELAYS

TYPE IJF518

TRIP CIRCUIT FOR IJF518 SAME AS ABOVE.

0£\I'ICE FUNCTION NUWBERS

52 - (/,;-CUlT BREAKER 81 - �RECUENCY RElAY, TYPE IJF

a - AUX.CCIHACT,CLOSEO WHEH BREAkER IS CLOSED

OC - OPERATING COIL RC - RESTRAINT COIL TC - TRIP CO! l

• =SHORT FINGER

*Fig. 9 (K-6400202 (2]) Type IJF52A Relay, Internal Connections, (Front View)

Fig. 10 (K-6154254-3) Typical External Connections For The Type IJF51A and IJF51B Relays

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Frequency Relays Type IJF G E I-19008

RENEWAL PARTS It is recommended that sufficient quantities of

renewal parts be carried in stock to enable the prompt replacement. of any that are worn, broken, or damaged.

When ordering renewal parts, address the

nearest Sales Office of the General Electric Com­pany, specify quantity required, name of part wanted, and give complete nameplate data, including serial number. If possible, give the General Electric Company requisition number on which the relay was furnished.

A-C BUS 1

----.-�------------------------------------------ 2

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TRIP BUS t+) -+-------=----

5

6

EXTERNAL CAPACITATOR

RESISTOR

8

a 52 TC

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DEVICE FUNCTION NUMBERS

52 - CIRCUIT BREAKER 81 - FREQUENCY RELAY TYPE IJF

a - AUXILIARY CONTACT CLOSED WHEN BREAKER IS CLOSED

OC1- OPERATING COIL FOR UNDER-FREQUENCY OC2 - OPERATING COIL FOR OVER-FREQUENCY S! - SEAL-IN UNITS - UNDER AND OVER-FREQUENCY TC - TRIP COIL

Fig. 11 (K-6375802-1) Typical External Connections for Under-Frequency and Over-Frequency Protection of an A-C Bus Using One Type IJF52A Relay.

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10

GEI-19008 Frequency Relays Type IJF

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232Mt-1

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2' 187 56MM

4 ' 375---r-111 MM

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PANEL LOCATION

6.625 SEMI-FLUSH SURFACE �TG. MTGl

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5/16-18 STUDS SURFACE MTG. 168Mt-1

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STUD NUMBERING

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<TYPICAL) 144MM

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19MM FOR SEMI-FLUSH MOUNTING PANEL D�ILL�NG FRONT VIE�

TYPICAL DIM.

INCHES MM

FOR SURFACE �OUNTING FRONT VIEW

3. 0 I 76MM .,._

5/16 -18. STUD

VIEW SHOWING ASSEMBLY OF HARDWARE

FOR SURFACE MTG. ON STEEL PAN�LS

*Fig. 12 (K-6209271 [8!) Outline and Panel Drilling Dimensions for Type IJF Relays

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ST-3/94 (400)

Meter and Control Business Department

General Electric Company 205 Great Valley Parkway Malvern, PA 19355 www .

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