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CURRENT
Time
Characteristic
Inverse
Inverse
Very
Inverse
Very
Inverse
Extr. Inverse
Extr.
Inverse
*The impedance values given are those for the minimum tap of each relay.
The impedance for other taps, at pickup current (tap rating), varies
inversely approximately as the square of the current rating. Example: for
the Type IBCGSlM relay, 0.5/4 amperes the impedance of the 0.5 ampere tap
is 22 ohms.
approximately (0.5/l)! x 22 = 5.5 ohms.
+ Some companies list relay burdens only as the volt-ampere input to
operate at minimum pickup.
can be made.
CT secondary circuit, since the burden at five amperes is used for this
purpose.
Inst
Unit
Amps
Hz Range
6 0
*Indicates Revision
BURDENS AT 60 CYCLES OF THE TDC UNIT
CIRCUIT
Burdens at Minimum Pickup
Range Eff. Res. React. **Imped +Volt
(Amps) (Ohms)
5.60
0.37
1.40
0.23
0.80
0.005
The im edance of the one ampere tap, at one ampere, is
This column is included so a direct comparison
should not be used in calculating volt-ampere burdens in a
It
TABLE 10
BURDEN OF THE INSTANTANEOUS UNIT
Min .
Range
Pickup
Amps
Amps
6 0.110 0.078 0.135 0.095 0.081
30 0.022 0.005 0.023 0.022 0.022 0.222
GEK-49922
TABLE 9
Amps P.F. Min P.U. Min P.U. Amperes
(Ohms) (Ohms)
21.0
22.0
5.5
1.44
5.8
1.49
3.90
4.15
1.0
0.53
0.58
1.3
1.38
1.60
0.4
0.4
0.147
0.17
Burden at Min
Pickup (Ohms1
R
Z
10
3 Times 10 Times At Five
0.25
10.80
5.00
0.25
0.65
0.32
0.33
4.20
2.90
0.58
0.36
0.50
1.60
1.60
0.50
0.17
0.17
Burden Ohms (Z)
Times Pickup
3
10
0.079
555.0
36.3
104.0
14.5
40.0
4.25
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