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INSTRUCTIONS
GEK-34055C
Sup ersedes GEK-340558
0
TIME OVERCURRENT RELAYS
.· -
TYPES
IAC77A FORM 800 AND UP
IAC77B FORM 800 AND UP
IAC78A FORM 800 AND UP
IAC78B FORM 800 AND UP
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GENERAL
ELECTRIC
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Summary of Contents for GE IAC77B
- Page 1 GEK-34055C Sup ersedes GEK-340558 TIME OVERCURRENT RELAYS .· - TYPES IAC77A FORM 800 AND UP IAC77B FORM 800 AND UP IAC78A FORM 800 AND UP IAC78B FORM 800 AND UP GENERAL ELECTRIC - - -- - - - " - •...
- Page 5 CONNECTIONS . TY PE UNIT CIRCUITS FIG. 4 IAC77A FIG. 5 IAC77B IAC78A FIG. 6 FIG. 7 IAC78B APPLICATION Tne extremely inverse time current characteristics make the IAC77 and IAC78 relays particularly well suited for the protection of primary distribution circuits.
- Page 7 CYCLES UNIT 0. 5 - 4.0 IAC77A and 1. 5-12.0 IAC78A 2.0- IAC77B and 0. 5 - 4. 0 0. 5 - 4. 0 1. 5 - 1 2.0 IAC78B 2.0 - 16. 0 2. 0 - 15. 0 10. 0 - 80.0 20.
- Page 9 GEK-3 40 55 The one second thermal ratings are listed in Table IV. TABLE IV TIME OVE RCUR RENT UNIT 1-SEC. RATIN G (AMPS) (AMPS) 0. 5 - 4. 0 125. 0 15.625 1.5 - 1 2. 0 260:0 260.0 67 , 600 For ratings of less than one second, the rating may be calculated according to the formula where T is the time in seconds that the current flows.
- Page 10 · · · �...
- Page 11 GEK-34055 TABLE VI * ONE RANGE CONTINUOUS SECOND RATING 0. 5-4.00 0.5-2.00 0.75 25.0 2500 1. 0-4. 00 1. 5 50. 0 16900 2. 0-16.0 2. 0-8. 00 3. 0 130. 0 4. 0-16. 00 67600 6. 0 260. 0 10.0-80.0 10.
- Page 13 GE K- 3 40 55 TABLE VIII RANGE MIN. BU RDENS AT MIN. BU RDENS IN V. A. AT 5 AMPS PICKUP MIN. TAP OHMS (Z) CALCULATED FROM IMPEDANCE AT MIN . �) PICKU P ( I TIMES TIMES TIMES PICKUP PICKUP PICKU P 0.
- Page 14 ·�.
- Page 15 GEK-3405 5 If injury or damage resulting from rough handlin g is evident, file a damage claim at once with ·transit. the transportation company and promptly notify the nearest General Electric Apparatus Sales Office. � Reasonable care should be exercised in unpacking the relay in order that none of the parts are in- ed or the adjustments disturbed.
- Page 17 GEK-34 0 55 ed by non-sinusoidal wave forms. TIME OVERCURRENT UNIT Rotate the time dial slowly and check by means of a lamp that the contacts just close at the zero time dial setting. Where the contacts just close can be adjusted by running the stationary contact brush in or out This screw should be held securely in its support.
- Page 19 GEK-34055 TESTS PICK UP With the unit connected for high range operation (parallel connections) and the target in the " Down" ;ition, check the pickup at the maximum calibration mark: the pick up should be within the limits in 1dble TABLE X TARGET AND SEAL-IN UNIT The target and seal-in unit has an operating coil tapped at...
- Page 21 GEK-3 40 55 INSTANTANEOUS UNIT Select the desired range by making the proper connections at the rear of the relay (See Internal Connections Diagram). Whenever possible, always select the higher range since it has higher continuous rating. Set the instantaneous unit to pick up at the desired current level. See �setting the Instantaneous Unit�, ion the "Acceptance Test Section."...
- Page 25 GEK-340 55 TABLE XIV 60 HZ 50 HZ MAX. SEC. M IN. SEC. M IN. SEC. M AX. SEC. AMPS 7.22 6.58 7. 56 6.27 0 .30 0 .26 20.0 INSTANTANEOUS UNIT Both contacts should close at the same time. The backing strip should be so formed that the forked end front bears against the molded strip under...
- Page 27 GEK-34 055 • MAIN BRUSH CONNECTING PLUG CONNECTING BLOCK • • AUXILIARY TE RMINAL B LOCK SHORT ING NOTE: AFTER E NGAG ING AUXILIARY BRUSH, CONNECTING PLUG TRAVELS INCH BEFORE ENGAG ING THE MAIN BRUSH ON THE TE RMINAL BLOCK •...
- Page 31 GEK-34055 CRADLE • RESISTOR CAPACITOR UNIT RANGE SELECTOR LEADS • FIG. 3 (8041297 ) TYPE IAC77 800 SERIES RELAY REMOVED FROM CASE (REAR VIEH)
- Page 33 GE K- 34 05 5 T&SI IN O T&SI T&SI SHORT I NGERS � FIG. ( 01 65A7758-0 ) TYPE IAC77A 800 SERIES RELAY INTERNAL CONNECTIONS {FRONT VIEW)
- Page 37 GE K-3405 5 INDUCTION UNIT T&SI Fl NGER SHORT FIG. 6 (0165A7781-0 ) TYPE IAC7RA 800 SERIES RELAY INTERNAL CONNECTIONS (FRONT VIEW)
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Page 39: Instantaneou S Unit
GEK-34055 � INSTANTANEOU S UNIT OVERCURRENT TIME '-.""-, "· """ � \ � : T� WOUND : : s [ S HADING COIL S =SHORT FINGER T �Sl :TARGET SEAL -IN NOTE :-INSTAN TANEOUS UNIT CONNECT IONS SHOWN ARE FOR OPERATI ON. - Page 41 GEK-34055 0.030 OPERATING TIME RANGE FOR ANY 0.02� PICKUP SETTING � Cr20 n... � 0.010 0.005 MULTIPLES OF PICK-UP FIG. 8 ( K-6306872- 5 ) TIME CURRENT CURVE OF THE INSTANTANEOUS UNIT...
- Page 47 GEK-34055 PANa LOCATION SURFACE SEMI-FLUSH U68MM) 6:;Q!"- \.157MM) 9.12S OUTLINE r5.687 (ISMM) � CUTOUT .218 DRILL (144MM) l5MM REPLACE (2 HOLES) DRILLED HOLES (OPTIONAL) �.40� I ll DRILL (10 HOLES) (19MM) IAC78B 800 Fig. (K-6209271-5) Outline and Panel Drilling for the Series Relay...
- Page 49 GEK -3 40 5 5 STUDS JU.tBERING OF ( FROHT VIEW) ou·rLINE �LLHG SEMI-FLU SH �f£L r.o.MTNG (FRONT \/£W) �L DRILLING FOR SURFAC£ '-«>LNTING &FRONT 'lEVi\ VIEW SH•:NtiNG A5SEMB.. Y OF HAROWAFiE: FOR SURfACE WTG. ON STEEL PANELS FIG. 12 (K-6209270-2 ) OUTLINE AND PANEL DRILLING FOR TYPES IAC77A, IAC778 AND IAC78A 800 SERIES RELAYS...
- Page 53 GEK -34 055 A-C BUS TRIP �-M:.L 5t H 51-2 51-1 (- ) FIG. 14 (0246A6966-0 EXTERNAL CONNECTIONS OF FOUR IAC77A RELAYS USED FOR MULTI-PHASE A ND P�ASE TO TO GROIJND FAULT PROTECTION O F A 3-PHASE CIRCUIT...
- Page 55 GEK-34055 51-2 51-1 ..§ZL � ( t) D - C TRIP 51-2 � � FIG. 15 0246A6967-0 EXTERNAL CONNECTIONS OF FOUR IAC78A RELAYS PROTECTING A 3-PHASE CIRCUIT AGAINST MULTI -PHASE AND PHASE TO GROUND FAULTS GENERAL ELECTRIC CO., POWER SYSTEMS MANAGEMENT BUSINESS DEPT., MALVERN, PA. 19355 3-80...