Electronic protection of overvoltage shunt circuit elements - detects rate of impulses in shunt and switches network off if threshold is exceeded

摘要

A logic network is used for protecting overvoltage shunt circuit elements against overheating, and thus for protecting the entire network concerned. Basically, the logic network determines the rate of use of the overvoltage shunt, and if this exceeds some given threshold, then the whole system is switched off. This is achieved by means of an up-down counter (Z) which is driven in a downwards direction by a clock (G) and in an upwards direction by impulses received from the overvoltage shunt. The contents of the counter are not allowed to fall below zero. A comparator element detects when the counter contains a particular number, corresponding to the threshold and if this happens a signal is produced to switch off the entire system.