input output unit
The Input/Output Unit with Isolator provides two voltage-free, single pole, change-over relay outputs, a single monitored switch input and an unmonitored, polarised opto-coupled input.
The Input/Output Unit supervises one or more normally-open switches connected to a single pair of cables.
The Input/Output Unit is fitted with a bi-directional short-circuit isolator and will be unaffected by loop short-circuits on either loop input or output.
The Switch Monitor with Isolator is designed to monitor the state of one or more single pole, volt-free contacts connected on a single pair of cables. It also reports the status to Apollo compatible control equipment.
The Switch Monitor with Isolator provides four input states to the control equipment: 'Normal', 'Fault', 'Pre-alarm' and 'Alarm'. These are derived from the switched resistive values shown in Table 2 overleaf. The Switch Monitor with Isolator has a red LED to indicate an alarm and two yellow LEDs to indicate a switch input wiring fault or a loop short-circuit wiring fault.
The Switch Monitor with Isolator is fitted with a bi-directional short-circuit isolator and will be unaffected by a single short-circuit on either loop input or output. For further information on isolators please refer to datasheet PP2090, available on request.
The Zone Monitor with Isolator returns a preset analogue value when all detectors on the zone are in quiescent state. A different value is returned when a detector changes to the alarm state. The Zone Monitor with Isolator latches in the alarm state.
The Zone Monitor with Isolator is fitted with a bi-directional short circuit isolator and will be unaffected by loop short circuits on either the loop input or loop output.