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Tbe 0.2 ampere tap is for use with trip coils
operate on currents ranging from 0.2 up to
2.0 amperes at the
tap is used with trip coils requiring more than
2 amperes, there is a possibility that the resistance
of ohms will reduce the current to so low a value
that the breaker
not be tripped.
The
tap should be used with trip
that take 2 amperes or more at minimum
control voltage, provided the current does not exceed
30 amperes at the
the tripping current exceeds 30 amperes, the con-
nections should be arranged so
unit contacts will operate an auxiliary relay which
in turn energizes the trip coil or coils.
TABLE
UNIT RATINGS
Inverse
Inverse
Inverse
Very
Very Inverse
Very Inverse
Inverse
Inverse
The impedance values
at pick-up current (tap rating), varies inversely approximately as the square of the current rating.
Example: for the Type
The impedance of
+ Some companies list relay burdens only as the volt-ampere
column is included so a direct comparison can be made. It should not be used in calculating volt-ampere
burdens in a CT secondary circuit, since the burden at 5 amperes is used for this purpose.
Calculated from burden at minimum pickup.
Courtesy of NationalSwitchgear.com
Ground Directional
control voltage.
control voltage.
the induction
such
0.2 AMP
TAP
TAP
CIRCUIT
OF DIRECTIONAL AND OVERCURRENT
UNIT OPERATING COILS AT GO CYCLES
BURDENS AT MINIMUM PICKUP
Res.
React.
Ohms)
8.00
20.0
22.5
1.00
2.65
0.32
0.76
2.20
5.10
0.36
0.17
0.26
0.44
1.12
1.40
0.13
0.16
0.042
0 . 3 6
are those for the minimum tap of each relay. The impedance for other taps,
relay,
amperes theimpedance of the 0.5 ampere tap is 22.5 ohms.
1 ampere tap, at 1 ampere, is approximately
an application, it may be necessary to connect a
loading resistor
relay coil to allow enough current to operate the
this
target seal-in unit.
CONTACTS
The current-closing rating of
contacts is 30 amperes for voltages not exceeding
250 volts. Their current-carrying rating is limited
by the tap rating of the seal-in unit.
The capacitive burden of
circuit of the directional unit at GO cycles and 12
volts is 19.6 volt-amperes at 0.78 power factor.
The burden of the current polarizing circuit of the
directional unit at 80 cycles and 5 amperes is 8.6
volt-amperes at 0.95 power factor. Table IV
the current circuit burdens of the directiona and
overcurrent unit operating coils (studs 5-6).
Ordinarily, the potential
corner of broken delta potential transformers and
current circuits are
current transformers.
only imposed for
and need be considered only for this brief period.
TABLE IV
+ Volt-
Factor
5.60
0.36
2.90
0.35
0.83
13.3
0.38
5.60
1.40
0.40
0.96
0.85
0.43
0.51
8.15
0.51
1.80
0.46
0.62
0.21
0.41
0.62
0.053
0.88
0.65
to operate at minimum pickup.
Relay Type IBCG
parallel
induction unit
BURDENS
is in the open
the residual circuits of
The burden is, therefore,
duration
the ground fault
I
IMPEDANCE Al
3
Min.
13.4
7.80
1.70
1.00
0.49
0.65
5.30
4.50
0.81
0.88
0.51
0.46
1.80
1.79
0.20
0.21
0.054
0.055
X 22.5
5.63 ohms.
GEH-2032
auxiliary
1
At Five
560.0
13.0
20.7
140.0
22.0
12.1
46.0
5.2
1.38
5
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