ELECTRONIC SAFETY AND HEAT CONTROL MEANS

摘要

ELECTRONIC SAFETY AND TEMPERATURE CONTROL MEANS This invention relates to an electronic safety and heat controlling means, mainly for heat mats and concreting cassettes to be used on building sites. It comprises a temperature regulating device, fuses operating as overload protection, a setting device, a testing device and an indicator to indicate the operative condition of the means. This electronic means is characterized in that a differential current measuring and control means has been disposed to control the main circuit over a relay on the basis of the difference between the current going to and that returning from the load. A switching means has been disposed to isolate the load from the means when a fuse responds or when one of the mains conductors or the ground conductor breaks.