GEK-45464
curren t exceeds i ts sens i ti v i ty, the re can be some v a r i a t i on i n t i mi ng on a
stat i s t i cal bas i s, d epend i n g on what i n sta nt i n the current cycl e the DC vol ta ge i s
appl i ed. I n order to l i mi t th i s va r i ati on, i t i s recommended tha t the i nput current
to the rel ay be sel ected i n the ra nge of 5 to 10 t i mes the pi ckup sett i ng. Thus,
for sett i ng th i s t i me r i t i s sugges ted that s i ngl e-pha se cur ren t be fed i n to the
g round ci rcui t w i th the ground pi ckup sett i n g on the mi n i mum pos s i bl e sett i n g. Th i s
i nput curren t s houl d then be sel ected to be about 5 to 10 t i mes the RMS v a l ue
re qui red to get a con t i nuous output from the curren t detecto r.
Th i s a rra ngement
wi l l l i mi t the sta t i st i cal var i a t i on to some fract i o n of a mi l l i s econd. The ci rcui t
a nd the i nstruct i ons to make these sett i ngs a re g i ven i n the sect i o n und e r
ACCEPTANCE TESTS.
It s houl d be noted that wi th the above sett i ngs the re l ay w i l l , fo r seve re faul ts,
ope rate i n the se t t i me.
For l ow-current faul ts, i t may ge t a few mi l l i seconds
s l owe r, wh i ch i s i n the d i rect i on to prov i de sl i ghtly mo re ma rgi n for these faul ts
whe re s tabi l i ty and damage con s i dera t i on s a re cons i de rabl y l e ss onerous.
The second a ry ( B/0) t i me del ay i s set w i th the AND2 l i nk i n the OUT pos i ti on a nd
w i th no i nput cur rent. The con tact conve rter ( CCI) must be energ i zed a t the same
t i me a s the powe r suppl y. Te rm i nal s 9 a nd 17 can be connected to gether a nd then
swi tched to +DC for i n i t i a t i on of the B /0 t i mer.
After sett i ng the t i me del ay, the pi ckup sett i ngs on phase a nd ground currents
shoul d be ma de, a s i nd i ca ted i n the s ect i o n under
ACCEPTANCE TESTS.
The
co n s i d e ra t i ons rel a ted to the actua l sett i ngs to sel ect have been d i scussed i n the
s ect i o n under
APPLICATION.
OPERATING PRINCIPLES
INTRODUCTION
The ope ra t i n g sequence o f l og i c s i gnal s for each o f the SBCs can be fol l owed wi th
the a i d o f the proper i n te rnal connect i on s d i agram, as s hown bel ow:
RELAY TYPE
SBC23A
SBC23B
SBC2 3 C
FIGURE
2 3
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25
Al l the SBCs con ta i n funct i onal el ements as de scr i bed bel ow:
A)
+10.2V, -10.2V DC zene r- regul a ted powe r suppl y wi th RF surge suppres s i on
(Pri n ted C i rcui t Ca rd i dent i fi ed a s 11Y11 )
B )
Powe r suppl y l evel -sens i n g ci rcui t, to prevent pi ckup i f te rmi nal #17 i s
grounded
C )
A C ci rcu i t surge suppres s i on ( Cl through C8)
D)
Tr i pl e ra nge p r i ma ry tapped tra nsacto rs a nd tap bl ocks fo r PhaseA, Phases,
Phasec, 3Io current ci rcui ts ( TRA, TRB, TRC, TRD; TBl, TB2, TB3, TB4 )
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