Dc Oper A T Ed Con T A Ct Or - Hitachi H20-T Technical Notes

(1) Dir ect inpu t coil t ype
Beca u se of t h e t em per a t u r e r ise of t h e coil, DC elect r om a gn et is la r ger t h a n AC on e, t h u s DC oper a t ed con ta ct or
is h igh er t ha n AC oper at ed on e.
(Opera t ion )
Wh en t h e coil is excit ed, t h e m ovin g core is a tt r a ct ed t o t h e fixed cor e, a nd t h e m ovin g con ta ct link ed t o t he movin g
cor e com es in t o cont a ct wit h th e fixed con t act, t hen closes t h e circu it. When t h e coil is r elea sed fr om excit ed con di-
t ion, t h e movin g core sepa ra t es from t h e fixed cor e a n d t he m ovin g con t act par ts from t h e fixed cont a ct , t h en opens
t h e circu it.
(2) Dou ble coil t ype
Th e dim en sion of dou ble coil t ype DC oper a t ed con t a ctor is t h e sa me a s t h at of AC oper a t ed on e. Th e dou ble coil
is a coil wh ich h as 2 coils, closin g coil a n d h oldin g coil woun d on th e coil bobbin.
(Opera t ion )
Wh en a volt a ge is applied to t h e coil, a cu rr en t flows on ly t o t h e closin g coil, t h e m ovin g cor e is a tt r act ed t o t he fixed
cor e, a n d t h e movin g con t a ct link ed t o t h e m ovin g core com es in t o con t a ct wit h t h e fixed con t a ct , t h en closes t h e
cir cuit. A cu r ren t flows t o bot h t h e closin g coil a n d t he h oldin g coil just befor e t h e movin g cor e com es int o con t a ct
with th e fixed cor e; t h e cur r ent is r edu ced by a lar ge r esist a n ce of t h e h oldin g coil, a n d as a result, t h e t em pera t u r e
r ise of t h e coil is cont r olled. Th e oper at in g circu it is as shown in Fig. 13.
F ig. 11 Direct inpu t coil t ype F ig. 12 Dou ble coil t ype
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