Neutral Protection

Neutral protection protects neutral conductors against overheating.

• For a three-pole circuit breaker, neutral protection is possible if a neutral current transformer is used.

  • Adjust the neutral using the trip unit keypad.

  • Possible settings are OFF, N/2, N, or 1.6N.

  • Factory setting is OFF.

  • Oversize neutral protection (1.6N) requires use of the appropriate oversize neutral current transformer.

CAUTION

Hazard of equipment damage If a four-pole circuit breaker neutral pole switch is set to 4P3D setting, the current in the neutral must not exceed the rated current of the circuit breaker. For a three-pole circuit breaker with oversize neutral protection (1.6N), select the appropriate oversize neutral current transformer. Failure to follow these instructions can result in injury or equipment damage.

• For a four-pole circuit breaker, set system type using the circuit breaker neutral selector dial .

  • Make fine adjustments using the trip unit keypad, with the circuit breaker dial setting providing the upper limit for adjustment.

  • Factory setting is 4P4D.

• Neutral protection conductor type has four possible settings:

  • Off—Neutral protection is turned off.

  • N/2—Neutral conductor capacity is one-half that of the line conductors.

  • N—Neutral conductor capacity is the same as that of the line conductors.

  • 1.6N—Neutral conductor capacity is 1.6 times that of the line conductors. (Three-pole circuit breaker only.)

Four-Pole Circuit Breaker Neutral Selector Dial