NEWSLETTER APRIL 2006

Neutral Conductor failure means damage

The new ENYA-series will be equipped with another WatchDog in the form of a three-phase voltage monitor. In addition to the up to now presented undervoltage-monitors the new E1PF is scanning the power system for symmetry and the clockwise rotation. Furthermore phase failures can be detected. The output of the device is a change-over contact for reporting of failure or breakdowns or for immediate switching operation. The energised relay signals that symmetry and phase sequence are in order. The Asymmetry is variably adjustable from 5-25% dependent on the sytem. The asymmetry detection can also be switched off if only the direction of rotation is of interest.

For mobile applications it is recommended to define the direction of rotation directly on the part of the installation before putting into operation. E.g.: Compressor with self-ventilation, cooling in counter-clockwise rotation, is not effectual and so special attention is dedicated to the direction of rotation out of the power supply.

Asymmetries can be a result of irregular burden of the consumer loads, or above all by a broken neutral conductor. This situation is commonly feared, because most of all one-phase consumers will be damaged. Ecspecially mobile installations on stages are endangered, but also stationary systems are at risk.

With the combination of the phase-monitor and a contactor, damage caused by defective power supply, can be avoided. The E1PF is able to be supplied by its own three-phase power pack even within unsymmetric power system, without carrying any damages. This means, that the phase monitor is connected in front of the switching contacts to relieve supply voltage as soon as everthing is back to normal.

The new phase-monitor can also be used for consumer loads without neutral point (e.g.: asynchronous motor with delta connection). Phase failure within the supply line can still be detected by quantifying the symmetry, even with a revolving AC motor reinducting voltage into the system.

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