DOCA0218EN-00

Neutral Protection

Protection of the Neutral Conductor on Four-Pole Circuit Breakers

Protection of the neutral conductor depends on the distribution system. There are three possibilities.

Type of neutral

Description

Neutral unprotected

The distribution system does not require protection of the neutral conductor.

Half neutral protection (at 0.5 In)

The cross-sectional area of the neutral conductor is half that of the phase conductors.

  • The long-time current setting Ir for the neutral is equal to half the setting value.

  • The short-time pickup Isd for the neutral is equal to half the setting value.

  • The instantaneous pickup Isd (MicroLogic 2.0 A/E) for the neutral is equal to half the setting value.

  • The instantaneous pickup Ii (MicroLogic 5.0 A/E / 6.0 A/E / 7.0 A) for the neutral is equal to the setting value.

Full neutral protection (at In)

The cross-sectional area of the neutral conductor is half that of the phase conductors.

  • The long-time current setting Ir for the neutral is equal to the setting value.

  • The short-time pickup Isd for the neutral is equal to the setting value.

  • The instantaneous pickup Isd and Ii for the neutral are equal to the setting value.

Neutral Protection for Three-Pole Devices

Neutral protection is not available on three-pole devices.

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