Ap Plication; Construction - GE IFC66A Instructions Manual

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.I
The type IFC relays covered by these instructions are singl e-phase time overcurrent rel ays with l ong­
time characteristics, used primari l y for motor protection .
time overcurrent unit and a dua l -rated target and sea l -in unit.
hinged-armature instantaneous overcurrent unit with target, mounted in the front of the re l ay.
incl udes the Hi- Seismic instantaneous unit in the front, and a l so a high dropout unit a l so with Hi-Seismic
capabi l ity mounted in the rear.
pickup setting and does not incl ude a target.

CONSTRUCTION.

0
When semif l ush mounted on a suitab l e panel these rel ays have a high seismic capabi l ity .
re l ays are recognized under the Components Program of Underwriters Laboratories, Inc.
The re l ays are mounted in a C l drawout case of mo l ded construction .
shown in Figures 20 and 21 .
in Figures 3 , 4 and 5 respective l y.
Time overcurrent rel ays are extensive l y used for protection on util ity and industria l systems.
l ong-time inverse characteristic of the IFC 66 fami l y is useful for overl oad protection on l arger medium
vo l tage motors and as l ong -time back-up protection on medium-vol tage industria l systems.
The principa l app l ication of the IFC66A and IFC 66B re l ays is for motor protection.
acteristic �f the induction disk unit provides sufficient time to prevent operation on motor starting current.
In this appl ication the re l ay settings are frequent l y determined by Nationa l E l ectric Code requirements as
we l l as by consideration of the motor therma l heating and starting characteristics .
in the IFC66B if used must be set above l ocked rotor current.
instantaneous unit a setting of twice-l ocked rotor current is usua l l y recommended.
can be made by using the transient overreach curves in Figure
The IFC66A and IFC 66B re l ays are a l so useful for appl ication on the primary of a smal l l ow vo l tage l oad
center transformer when the secondary main protective device is an insul ated case circuit breaker.
cases the l ong time capabil ity permits the re l ay to be set se l ective l y with the non -adjustabl e l ong-time
therma l e l ement of the l ow vol tage breaker.
app l ication on l y when it can be set above the magnitude of current at the re l ay location for a fau l t at the
l ow-vo l tage termina l s of the transformer.
in Figure 8.
The IFC 66 K is especia l l y suited for motor protection .
second instantaneous overcurrent unit, with a high
high dropout instantaneous unit is to provide discr1mination between motor running overl 0ad and l ocked
rotcr current .
This is accompl ished by setting pickup of the high drop-out unit ( 5 0/ B) between motor ful l ­
l oad current and l ocked rotor current, as i l l ustrated in Figure 9, with the normal j ropout instantaneous
unit ( 5 0/A ) set above l ocked rotor current .
thermal l imit . Typical settings to accomp l ish this are l isted in the fo l l owing tab l e:
T:tc�c {_Jt�
t"Lu.C-ttOtL� de not: /Xv"!.pc'tt t o C.CVC"1. aL£ deA:.aA.L� O!t vOJU.a.tio;v., -<.n e_q
eve":.�' pc��-<.bic c.c1Ltingcnc. u to be. mc.t:
: ] u.:.t:tc"L (nJc"tmaUclt be dc. � -0ted o:r:_ �:wuJ.d ;-- a 'tuc.ul.LLt p
tltc :.'u":.du:z.�"-"1.'�
Te titc e_ :dc1:t ·u.:.Ju.{_:c_d tltc_ ptcduc.,t�
;tc·
�t<Gt a,��u.'l.a.Jtc.e -0� g(ven tvi.. t lt tc�: : ; c.c.t tc t.cc.a.f. c.cd.c,� alld c-tdinanc.c.-� becaMe thc.y vMy g.te_at:.f.y.
T Y P E S IFC66A, IFC66B, IFC66K
The high drop-out unit is designed to drop out at
The re l ay internal connections are for the IFC66A, IFC66B and IFC 66K are shown
Time Overcurrent Unit
Normal Dropo ut Instantaneous
Overcurrent Unit
High Drop out Instantaneous
Overcurrent Unit
-<.n
ptt':i:;c � c__ � , :tite_
mat:t.:_t �lwu.id b e te6cne_d to the Gerte_,"LCLf. E.tect-"1.-i.c. Companu.
GE K-4 5 376
TIME OVERCURRENT
R ELAYS
R N
D ESC I PTIO
A l l three re l ay types inc l ude an induction disk
A l l units are described in detai l in the section on

AP PLICATION

11.
The instantaneous attachment in the IFC66B is useful in this
Typica l externa l connections for the IFC66A and IFC 66B are shown
The re l ay is simi l ar to the IFC66B except that a
dropout characteristic, is incl uded.
The time overcurrent unit must coordinate with the motor
Unit
5 1
50/A
50/B
c.onnecucn :edh -<.;v.,:ta.il.ctUort, opvz.a..t:i. . o n o!t maint:ertartc.e.
t o b.f. env., �e
-
dc�c.:.(bed
itc.-:.c.(n mec.- t appZ,(c.abtc ANSI, IEEE and I·.JE. ' .IA �talldCLtd�; bu.t
3
The IFC66B a l so incl udes a Hi-Seismic
80
The outl ine and pane l dril l ing are
To account for the transient overreach of the
More precise settings
Pickup Setting Mul tipl es
of Ful l Load C urrent
1 . 1 5 to 1 . 4
8
to 15
2 to 3
u.{.
pm e n-t: YlO.It to p.!tOv-i.de
whlch
Me not c.ove.�ted -6u66-i.ueHtiy &on
The IFC66K
percent or more of its
Al so, these
The
The l ong-time char­
The instantaneous unit
In such
The purpose of this
oM
Shoul.d