Powerohm Products

2400, 3300 & 4160 Volt Wye or Delta Systems

FLOOR-MOUNTED DIMENSIONS

OPERATION DESCRIPTION

Normal Operation: Under normal operating conditions, when there is no ground fault present on the systemand no current flowing through the resistor. An illuminated green indicating light, located on the front door, verifies normal operating conditions and proper control power. Ground Fault Condition: During a ground fault condition a red indicating light, locatedon the front door, will illuminate and thealarmcontactswill activate. The red indicating light and thealarmcontactswill remainactivateduntil theground fault is removed. During a ground fault, voltage will appear across the resistor. The resistor includes multiple taps to adjust the fault current to a value slightly greater than the system magnetizing current. The resistance taps can be factory set or adjusted at time of equipment installation. GroundFault Location: To locate theground fault, simply activate the pulse contactor by turning the selector switch, located on the front door, from the "Normal" position to the "Pulse" position. This activates a cycle of 40 pulses per minute toalternate theground fault current between the set magnitude and zero. Maintenance personnel can then use a portable clamp-on ammeter to follow the fluctuating fault current through the system to the location of the fault source. After removing theground fault, the selector switch is reset to stop the pulsing cycle. The green indicating light should illuminate to indicate that the sytem has returned to normal.

24"

90"

38"

30"

STANDARDNEMA1FLOOR-MOUNTEDENCLOSURE (NEMA 12 AND 3RHEIGHTS INCREASEBY 6 INCHES)

MEDIUM VOLTAGE WYE SYSTEMS

MEDIUM VOLTAGE DELTA SYSTEMS

PULSING CONTACTOR R

LINE FUSES

E S I S T O R

LINE FUSES

VOLT METER RELAY

PULSING CONTACTOR R E S I S T

ISOLATION SWITCH (DOOR INTERLOCKED)

VOLT METER RELAY

O R

120VAC

ISOLATION SWITCH (DOOR INTERLOCKED)

FUSES

NORMAL

CONTROL CIRCUIT

G

FUSES

NORMAL

LIGHTS

CONTROL CIRCUIT

G

R

LIGHTS

FAULT

R

TEST

FAULT

ALARM CONTACTS

TEST

ALARM CONTACTS

PULSE SELECTOR

PULSE SELECTOR