The tables 23, 24 below show, the operating currents for dif
ferent settings of operating
voltages and selected resistances. Adjust as required based on tables
23, 24 or to values
in between as required for the application.
Minimum ohms can be difficult to adjust due to the small value
compared to the total value.
Normally the voltage can be increased to higher values than the calculated minimum
TripPickup
with a minor change of total operating values as long as this is done by
adjusting the resistor to a higher value. Check the sensitivity calculation below for
reference.
Table 23: 1 A channels: input with minimum operating down to 40 mA
Operating
voltage
TripPickup
Stabilizing
resistor R
ohms
Operating
current level
1 A
Stabilizing
resistor R
ohms
Operating
current level
1 A
20 V 500 0.040 A -- --
40 V 1000 0.040 A -- --
60 V 1500 0.040 A 600 0.100 A
80 V 2000 0.040 A 800 0.100 A
100 V 2500 0.040 A 1000 0.100 A
150 V 3750 0.040 A 1500 0.100 A
200 V 5000 0.040 A 2000 0.100 A
Table 24: 5 A channels: input with minimum operating down to 100 mA
Operating
voltage
TripPickup
Stabilizing
resistor R1
ohms
Operating
current level
5 A
Stabilizing
resistor R1
ohms
Operating
current level
5 A
Stabilizing
resistor R1
ohms
Operating
current level
5 A
20 V 200 0.100 A 100 0.200 A -- --
40 V 400 0.100 A 200 0.200 A 100 0.400
60 V 600 0.100 A 300 0.200 A 150 0.400 A
80 V 800 0.100 A 400 0.200 A 200 0.400 A
100 V 1000 0.100 A 500 0.200 A 250 0.400 A
150 V 1500 0.100 A 750 0.200 A 375 0.400 A
200 V 2000 0.100 A 1000 0.200 A 500 0.400 A
The current transformer saturation voltage must be at least 2 ˣ TripPickup to have
suf
ficient operating margin. This must be checked after calculation of TripPickup.
1MRK 504 163-UUS A Section 7
Differential protection
Transformer protection RET670 2.2 ANSI 161
Application manual
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