GE Multilin G650 Manual page 262

5 SETTINGS 5.6 INPUTS/OUTPUTS
f) WITH DOUBLE VOLTAGE SUPERVISION AND SERIAL RESISTOR IN VOLTAGE MONITORS.
Figure 5–35:shows the supervision scheme with an external resistor.
An external series resistor is used with the 52a voltage monitor to prevent CB tripping with a short-circuited voltage monitor.
With CB open, 52/a is open and 52/b is closed. A shorted 52/a voltage monitor will not cause a trip because 52/b voltage
monitor is current limited to 2mA. With a shorted 52/b voltage monitor, no false trip will be performed because 52/a is in
series limiting current to 2mA.
5
Figure 5–35: SUPERVISION APPLICATION WITH AUXILIARY CONTACTS 52A AND 52B AND SERIES RESISTOR IN
F15-F16
GEK-113285A G650 Generator Protection & Control System 5-119