COPPLING SYSTEM FOR THE PURCHASE OF A TREATMENT CONSUMER IN THE NON-YMETRICAL EFFECT CONSUMPTION

摘要

The output of three current transformers, one in each phase feeding the load, is applied to a rectifier bridge whose output in turn energises the overload relay. The unbalanced load protection makes use of the voltage developed by this bridge across a loading resistor. The bridge voltage is applied via an integrator and potential divider to one input of an operational amplifier, whilst the other input is connected to the unsmoothed bridge voltage. The amplifier, which is connected in different mode, then gives an output dependant upon the a.c. component of the bridge voltage. In the case of unbalanced load the a.c. component will increase, and a level detector can be made to operate a trip when a predetermined level is reached.