GEK-49922
TABLE 9
CURRENT
CIRCUIT
BURDENS AT 60 CYCLES OF THE TDC UNIT
Burdens at Minimum Pickup
Impedance at
Time
Range Eff. Res. React.
3 Times 10 Times At Five
Characteristic
(Amps) (Ohms)
(Ohms) (Ohms)
Amps P.F. Min P.U. Min P.U. Amperes
Inverse
5.60
21.0
22.0
5.5 0.25 10.80
5.00
555.0
Inverse
0.37
1.44
1.49
5.8
0.25
0.65
0.32
36.3
Very
Inverse
1.40
3.90
4.15
1.0
0.33
4.20
2.90
104.0
Very
Inverse
0.23
0.53
0.58
1.3
0.58
0.36
14.5
Extr. Inverse
0.80
1.38
1.60
0.4 0.50
1.60
1.60
40.0
Extr.
Inverse
0.005
0.147
0.17
0.4 0.50
0.17
0.17
4.25
*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
relay,
amperes the impedance of the 0.5 ampere tap
is 22 ohms.
The im
of the one ampere tap, at one ampere, is
approximately
x 22 = 5.5 ohms.
+ Some companies list relay burdens only as the volt-ampere input to
operate at minimum pickup. This 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 five amperes is used for this
purpose.
Calculated from burden at minimum pickup.
TABLE 10
BURDEN OF THE INSTANTANEOUS UNIT
Inst
Min .
Burden at Min
Burden Ohms
Unit
Range
Pickup
Pickup
Times Pickup
Amps
Hz
Amps
Amps R
Z
3
10
6 0
6 0.110 0.078 0.135 0.095
0.079
30 0.022 0.005 0.023 0.022 0.022 0.222
*Indicates Revision
10
