GEK-49950
The d rawo ut co n nectio n/test system fo r the C1 case, shown i n F ig ure 1 4, h as pro visio ns fo r
1 4 co n nectio n po i nts, and a visib le cu rrent transfo rmer (CT) sho rti ng b a r located u p f ro nt.
As the co n nectio n plug is w ithdraw n, it clears the sho rter co ntact f i ngers i n the o utput
co ntact ci rcu its f i rst. Th us, the trip circuit is o pened b efo re any other ci rcu its a re
d isco n nected.
N ext, current-circuit f i ngers o n the case co n nectio n b lo ck engage the sho rting b a r ( lo cated
at the lower f ro nt of the case) to sho rt-circuit the external cu rrent-transfo rmer seco nd a ry
co n nectio ns. The w i ndow provides visual co nf i rmatio n of CT sho rting. The co n nectio n
p l ug then clears the cu rrent-circuit co ntact f i ngers o n the case, and f i nally those o n the
relay su ppo rt structure, to co mpletely de- energize the d rawo ut element.
A H ig h- Seismic target and sea l- in u n it is mo unted o n the f ro nt, to the left of the shaft of
t he t i me o vercurrent unit (see F ig u re 1). The seal- in u n it has two elect rica l ly sep a rate
co ntacts, o ne of w h ich is in series w ith its co i l and in paral lel w ith the co ntacts of the ti me
overcurrent u n it such that w hen the induct io n-u n it co ntacts close, the seal-in u n it p ick s u p
a n d seals i n. W hen the seal- i n u n it picks u p, it raises a target i nto view that latches u p a n d
remains ex posed u nti l released by pressing a reset b utto n located o n the u pp er l eft side of
t he cover.
The I FC
II
BD11 model relays co ntain, i n add itio n to the abo ve, a H igh-Seismic instantaneo us
u n it (see Fig u re 1 ). The i nstantaneo us u n it is a smal l h i nged-type u n it w it h electrica l ly
separate co ntacts and is mo u nted o n the f ro nt, to the right of the shaft of the time
overcu rrent u n it. One of its co ntacts is no rma l ly co n nected in paral lel w ith the co ntacts of
t he time-overcu rrent u n it and its co i l is co n nected i n series w ith the ti me-o vercu rrent u n it.
W hen t he i nst antaneo us u n it picks up it raises a target that l atches u p a n d rema i ns
exposed u ntil it is released. The same reset b utto n that releases the target sea l-in u n it also
releases t h e target of the i nstanta neo us unit.
A magnetic shield is mo u nted to the su ppo rt structure of inverse and very inverse time
overcu rrent I FC relays, to elimi nate the prox i mity effect of externa l mag netic mate rials.
Both the H ig h- Seismic target and seal- i n u n it and the H ig h-Seism ic i nstantaneo us u n it
h av e t he letters
II
H i-G
II
mo lded i nto their target b lo cks to disti nguish them as
u n its. Seismic
Level ex ceeds peak ax ial acceleratio n of 10 g's (4g ZPA)
tested
a b iax ial
i np ut motio n to prod uce a Req u i red Respo nse Spectru m
i n acco rdance w ith the IEEE G u ide fo r Seismic Testing of Relays, STD50 1- 1 978.
RATINGS
The relays a re designed fo r o peratio n i n an amb i ent air temperatu re f ro m -20°( to
+
55°(
TI ME -OVE RCURRENT UN IT
Ra ng es fo r t h e t i me-o vercu rrent unit a re show n in Tab le I.
4
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