Monitoring system for refrigerated display cases

Claim 1

A monitoring system for a plurality of refrigerating cabinets each having a separate time controlled defrosting system operating independently of said monitoring system for providing a defrosting period of increased temperature, said monitoring system comprising, a master indicating unit having a plurality of indicating lights operably connected to each of said cabinets, a defrost light and a warning light, thermally responsive switch means operably connected with each of said cabinets and actuatable by the increased temperature in the respective cabinet with said switch means electrically connected to one side of an electrical power source, each of said cabinet indicating lights having one lead electrically connected to the other side of the electrical power source and another lead being electrically connected to each of said thermally responsive switch means, resettable timing means having a timing period of predetermined duration which is longer than said defrosting period, circuit means including a relay, relay switch means, means for energizing said defrost light, means for initiating operation of said timing means when any one of said thermally responsive switch means is actuated and means for energizing the cabinet indicating lights corresponding to each thermally responsive switch means when the latter means is closed at the beginning of the defrost period, said circuit means further including a first series of diodes interposed one each between each of said cabinet indicatinG lights and said relay on one side thereof.