AbstractThis paper describes and implements an electronic relay scheme which protects industrial loads against overload and unbalance. The scheme works on a principle of integrating a pulse train. The strength of these pulses depends on the excess of current over the nominal value. It is shown that the presented scheme is capable of having variable overload protection characteristics. The relay design is directed to attain optimum overload protection that provides maximum use of motor and minimum waste operation time. The electronic circuit is described in details and different operating modes are studied. Experimental and analytical results are given and discussed.