Ground Directional
Relay Type IBCG
Fig. 2
Typical Comparison of Current, Potential or Dual Polarization of Type
Relay
Showing Effect of Local Ground Impedance
torque angle of degrees
When current polarized, it
operate at approxi-
mately 0.5 ampere with
operating and polarizing
coils connected in series. The performance of the
unit with simultaneous current and potential polar-
ization is typified Fig. 2.
The maximum operating current required to
close
time overcurrent unit contacts, at any
time-dial position,
be within five per cent of
the tap plug setting.
RESET
The minimum percentage of minimum closing
current
at which the time overcurrent
reset
is 90% for inverse-time relays and 85% for very in-
verse
extremely inverse time relays. When the
relay is de-energized, the time required for the disk
to completely reset to the number
posi-
tion is approximately 6 seconds for inverse time re-
lays and 60
seconds for very inverse and extremely
inverse time relays.
OPERATING TIME
The time curves of the time overcurrent
are shown in Figs. 16, 17 and 18 respectively for
inverse-time, very inverse-time and extremely in-
verse-time relays. For the same operating condi-
tions, the relay will operate repeatedly within one
or two per cent of the same time.
CURRENT COILS
The continuous and short time ratings of the
4
operating coil circuits are shown in Table The
current polarizing coils have a
rating of
5 amperes and a one (1) second rating of 150 amperes.
RATINGS OF OPERATING COIL CIRCUITS
Ratings
* Cont.
One Sec.
Rating
( A m p s )
1.5 100
l
*
1.5, 2, 2.5, 3, 4, 5, 6 5
200
4, 5, 6, 8, 10, 12, 16 10
220
l
The continuous rating of the operating circuit
limited by the directional
operating coil.
Applies to very inverse and extremely inverse
time relays only. The one second rating of in-
verse time relays is 65 amperes.
POTENTIAL COILS
The potential polarizing coils
withstand 120
volts for 20 minutes and 360 volts for 10
seconds.
UNIT
The rating and impedance of the seal-in unit
for the 0.2
and
2 ampere taps are given in
The
tap
used
by the trip coil.
