ABB RELION RET670 Applications Manual page 167

1MRK 504 163-UUS A
Transformer protection RET670 2.2 ANSI
Application manual
The tables 23, 24 below show, the operating currents for different settings of operating
voltages and selected resistances. Adjust as required based on tables 23,
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 Stabilizing
voltage resistor R
TripPickup
ohms
20 V 500
40 V 1000
60 V 1500
80 V 2000
100 V 2500
150 V 3750
200 V 5000
Table 24: 5 A channels: input with minimum operating down to 100 mA
Operating Stabilizing
voltage resistor R1
TripPickup ohms
20 V 200
40 V 400
60 V 600
80 V 800
100 V 1000
150 V 1500
200 V 2000
The current transformer saturation voltage must be at least 2 ˣ TripPickup to have
sufficient operating margin. This must be checked after calculation of TripPickup.
Operating Stabilizing
current level resistor R
1 A ohms
0.040 A --
0.040 A --
0.040 A 600
0.040 A 800
0.040 A 1000
0.040 A 1500
0.040 A 2000
Operating Stabilizing
current level resistor R1
5 A ohms
0.100 A 100
0.100 A 200
0.100 A 300
0.100 A 400
0.100 A 500
0.100 A 750
0.100 A 1000
Section 7
Differential protection
24
Operating
current level
1 A
--
--
0.100 A
0.100 A
0.100 A
0.100 A
0.100 A
Operating Stabilizing
current level resistor R1
5 A ohms
0.200 A --
0.200 A 100
0.200 A 150
0.200 A 200
0.200 A 250
0.200 A 375
0.200 A 500
or to values
Operating
current level
5 A
--
0.400
0.400 A
0.400 A
0.400 A
0.400 A
0.400 A
161