GE JBCG51M Instructions Manual page 13

B UR DEN OF NON- D I RECTIONALLY CONTROLLED I NS TANTA NEOUS UNIT
I N S T.
UNI T
H Z RANGE
6-150 60
The JBCG r e l ays cons i s t of three mai n un i t s , an i n st antaneous over current un i t
( top ) of the i nduct i on - cup type, a t i me over current un i t ( m i d d l e ) of the i n duct i on­
d i s k type, and an i n s t antaneous power d i rect i on a l un i t ( bottom ) of the i nduct i on cup
type. The d i rect i o n a l un i t c an be potent i a l and/or current po l ar i zed and, by means
of i t s c l os i n g contact s , d i rect i on a l l y cont ro l s the operat i on of bo th the t i me
over current un i t and i ns t antaneous overcurrent un i t s .
L2 {l arge doub l e-ended ) drawout case.
the TOC ( t i me overcurrent ) un i t each have an associ ate d t ar get and s e a l - i n un i t.
Mode l s wi th the Y1A s uff i x, as shown by Tab l e
i s of the hi nged- armature type.
D I RECTI ONAL UNI T
The d i rect i o n a l un i t i s of the i nduct i on - cyl i nder con struct i on wi th a l am i n ated
stator hav i ng e i ght po l es project i ng i nward and arr anged symmetr i ca l l y aroun d a
s t at i on ary central core.
the ann u l ar a i r
a l ternate l y wi th current operat i ng co i l s and poten t i a l po l ar i z i ng co i l s.
The pri n c i p l e by whi ch torque i s d e v e l oped i s the s ame as that of an i nduct i on
d i s k rel ay wi th a wattmet r i c e l ement, a l though, i n arr angement of p arts, the un i t i s
more l i ke a s p l i t-phase
prov i des hi gher tor que and
resul t i n g i n a f aster a n d more sens i t i ve r e l ay.
Low Grad i ent Cont act
The d i rect i on a l un i t cont acts ( l eft front ) whi ch contro l the t i me overcurrent
un i t are shown i n F i g.
to m i n i mi ze the effects of v i brat i on .
brushes are made of l ow gr ad i ent mater i a l whi ch,
to fo l l ow o n e another, hen ce, they res i s t contact separat i on.
The cont act d i al
mounted a con i c a l cont act t i p ( C ) .
contact brush ( E ) on whi c h i s mounted a button contact t i p (F ) .
mov i ng cont act brush bear s aga i n s t the i nn er face of the mov i n g cont act brush
ret a i ner ( G ) . S i m i l ar l y, the end of the s t at i on ary contact brush bears aga i n s t the
M I N I MUM
RANGE P I CKUP
L
6-30 6
H
30
30-150
CONSTRUCTION
The cup l i ke a l um i n um i nd uct i on rotor i s free to operate i n
gap between the po l es
lower rotor inertia than the i nduct i on motor.
They are of the l ow gr ad i en t type, s pe c i a l l y constructed
18.
( A ) supports the stat i on ary con tact brush ( B ) on whi ch i s
G EK-49849
11
TAB LE
BUR DEN A T M I NIMUM
P I CKUP (OHMS)
Jx
R
0.110 0.078 0.135
0.022 0.005 0.023
The I OC ( i n s t antaneous overcurren t ) un i t and
have an add i t i on a l I OC un i t whi ch
1,
and the core.
The i nduct i on - cyl i nder
Both the s t at i on ary a n d mov i n g con tact
when s ubjected to v i brat i on, tend
The mov i n g cont act arm ( D ) s upports the mov i n g
13
BUR DEN OHMS \Z)
TI MES P I CKUP
z
3 10
0.095 0.081
0.022 0.022
A l l un i t s are mounted i n the
The po l es are
construct i on
i nd uct i on -d i s k construct i on ,
The end of the
20
0.079
0.022
f i tted