MONITORING ARRANGEMENT FOR MONITORING A CHANGE FROM A NORMAL CONDITION OF ANY ONE OF A PLURALITY OF CONDITION SENSING DEVICES

摘要

ABSTRACT OF THE DISCLOSUREA monitoring arrangement for monitoring a change froma normal condition of any one of a plurality of conditionsensing devices. It includes a common two conductor circuitconnecting the condition sensing devices. A central monitoringapparatus is connected to the common two conductor circuit andsupplies current to the circuit. Each of the condition sensingdevices includes a device for limiting the amount of currentflowing therethrough from the common two conductor circuit; amechanism to detect and to react to any change from a normalcondition being sensed; and a mechanism to interrupt thecurrent to at least all following condition sensing devices inthe circuit upon reaction of the condition sensing device to achange in a condition being sensed. An apparatus is formed aspart of the central monitoring apparatus for measuring andindicating a magnitude of current being supplied to the commontwo conductor circuit at any given time.