The invention provides the electronic judging apparatus to detect the
working state of the other electric equipment without modifying it
inside. The common mode noise around the electric power supplying wires
of the other equipment is measured by using the special magnetic core
detector attached around the power supplying wire, and the common mode
noise is compared with the one measured on the non-working time after
amplifying and digital signal treatment of the detected signal. As the
modification of the equipment is not required, the monitoring of the
working state can be available for various equipments easily and also
available from a remote place by transmitting the digital treated signal
on the internet communication system.