NEUTRAL-EARTHING AND PHASE-NEUTRAL INDUSTRIAL FREQUENCY OVER-VOLTAGE PROTECTION METHOD AND DEVICE

摘要

The invention relates to a method and a device for protection against neutral-earthing and phase-neutral industrial frequency over-voltage, employed in single-phase and three-phase measuring and protection blocks and in switchboards equipped with adjustable or fixed differential circuit breakers. The disconnection of the consumer when phase-neutral and neutral-earthing over-voltage occurs is achieved thereby. The claimed method for protection against neutral-earthing industrial frequency over-voltage is characterized in that the over-voltage protection is achieved by using an electric transformer whose secondary winding delivers a current higher than the differential rated current of a non-modified differential circuit breaker, determining the release thereof. The claimed device for protection against neutral-earthing and neutral-phase industrial frequency over-voltage comprises a phase-neutral over-voltage protection block (B), a neutral-earthing over-voltage protection block (A) and an over-voltage display block (C).