GEK-34054
s i gn i fi ca n t ly
a ffect ed
by
t h e
a ppli ca t i on
of
n on - si n u soi da l
wavef or ms.
Ther efor e, i n or der to t est AC r elays pr oper l y i t i s essen t i a l t o
use a t est volt age and/or cur r en t wa vefor m t h a t i s si nusoi da l .
Th e
pur i t y of t h e si n e wa ve (i .e. , i t s f r eedom f r om ha r mon i cs) ca n n ot be
expr essed as a f i n i t e number f or any pa r t i cu la r r ela y; however , a n y
r el a y usi ng t u n ed
cir cuit s,
R L o r RC
n et wor ks,
o r
sa t u r a t i n g
elect r oma gnet s (such a s t i me-over cur r en t r elays) wou ld be especi a ll y
a f f ect ed by non -sinusoi da l wave f or ms.
TIME-OVERCURRENT UNIT
Rot a t e t h e t i me di a l slowly a n d ch eck, by mea ns of a lamp i n t h e
ci r cu i t ,
t h a t t h e cont act s ju st cl ose a t t h e zer o ( 0 ) t i me-dia l
set t i ng.
The poi n t at wh i ch t h e con ta ct s ju st cl ose can be a djust ed by
r u n n i n g t h e sta t i ona r y con tact
br u sh i n or ou t
by mean s of
i t s
a djust i ng scr ew.
Th i s scr ew shou l d be hel d secur el y i n i t s suppor t .
Wi t h t h e con t act s just closi ng a t No.
0
t i me set t i n g,
t h er e
shou l d be su ffi ci ent ga p bet ween t h e sta t i ona r y con t a ct br ush a n d i t s
meta l backi ng st r i p t o en su r e a ppr oxi ma t el y 1/3 2" wi pe.
The mi n i mu m cur r en t a t wh i ch t h e cont act wi l l ju st close i s
det er mi ned by t h e posi t i on of t h e t a p scr ew i n t h e t a p bl ock a t t h e
t op of t h e r el a y.
When changi ng t h e cur r en t set t i ng of t h e r elay wh i le i n t h e case,
r emove
t h e con n ect i on
pl u g,
t o shor t
t h e cu r r en t
t r a n sfor mer
seconda r y ci r cu i t .
Next , scr ew the t a p scr ews i n t o t h e t a p ma r ked
for t h e desi r ed cu r r en t , and then r eplace t h e conn ect i on plu g.
The p i cku p of t h e u n i t for any cu r r en t t a p set t i n g i s a djust ed by
means of a spring-adjusting ring (See Figure 2).
The ring may be
t ur ned by i nser t i ng a scr ew dr i ver in the not ches a r ound t h e edge.
By t u r ning t h e r i ng, t h e oper a t i ng cur r en t of t h e u n i t may be br ough t
i n t o a gr eement wi t h the t a p set t i ng employed, i f for some r ea son ,
t h i s a dju st men t has been di st ur bed.
Th i s a djust ment a lso per mi t s a n y
desi r ed set t i n g i n t er medi a t e bet ween t h e va r i ou s t a p set t i ngs t o be
obt a i ned.
The un i t is a djust ed at the fact or y t o cl ose i t s con t a ct s
fr om any t i me- di a l posi t i on a t a mi n i mu m cu r r en t wi t h i n
5%
of t he
t a p- pl u g set t i ng.
Th e un i t r eset s a t
90%
of t h e mi n i mu m closi n g
va l u e.
T i me
The set t i ng of the t i me di a l det er mi n es t h e l ength of t i me t h e
u n i t
r equ i r es t o cl ose it s con t a ct s when t h e cu r r en t r ea ch es a
pr edet er mi n ed va lue.
The con tacts a r e just cl osed when t h e di a l i s
set on
0.
Wh en t h e di a l i s set on 10, t h e di sk must t ra vel t h e
maxi mum a mou n t t o cl ose t h e con t a ct s; t h er ef or e t h i s set t i n g gi ves
t h e ma xi mu m t i me set t i ng.
The pr i ma r y a djust ment for t h e t i me of oper a t i on of t h e un i t i s
made by mea ns of t h e t i me di a l .
However ,
f ur t her a djust men t
i s
obt a i ned by movi ng the per manent magnet a l ong i t s suppor t i ng sh elf ;
12
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