Patent ID: 6337633
Filing Date: 2002-01-08
Classification: G08B

Abstract:
An alarm cable (1) including at least two electric connector devices (2, 3) selected from a number of different types of connector wherein each connector device includes an electric switch SW, which switch forms an electric switching loop (5) which is closed when the connector device is brought together with a female connector and is opened when the connector device is moved from a female connector, at least one alarm signalling device, and at least one electrically conducting wire (4) of the multi-conductor type to form electric connections between the alarm cable connector devices, wherein at least one connector device is connected to the conductors of a wire, whereof two conductors (6) at the first end area of the wire are connected electrically to each side of the respective switching loop of the connector device to form a current loop (7), characterised in that at least one connector device further comprisesa loop detector (8) having a plurality of inputs connected respectively to the respective switching loop of the connector and to two current loop conductors of the connecting wires at the other end area of the wires, which loop detector gives a signal when a change in one or more of the electrical properties of the current loops occurs or when there is a change of state in the aforementioned respective switching loop; a voltage detector (10), which voltage detector detects the presence of an electric voltage supplied from an external electric power source (9) through one or more connector devices and which gives a signal when there is a loss of voltage; a control circuit (11) connected to the loop detector (8) and the voltage detector (10), which control circuit gives a control signal of limited duration in response to the presence of a signal from the voltage detector only, which control circuit gives a prolonged control signal in response to the presence of a signal from the loop detector only, or on the concurrent presence of signals from both the loop detector and the voltage detector; and an alarm signalling device (12) which receives the aforementioned control signals and gives at least one alarm signal in response to the presence of a control signal.