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