Shunt Controller

The Shunt Controller allows two circuits to be temporally isolated from an active security system. The unit has two alarm inputs and each one is monitored by a 2K2 resistor. If this input is either open circuit or closed circuit the input is considered to be in alarm. Similarly the set input is also monitored by a 2K2 resistor. The set input controls the isolation of the other two inputs.

Four relays are provided for alarm annunciation and control. In addition a buzzer is provided for local feedback to users.

There are two modes of operation of the unit, timed and non timed, which are selected by using the on board switches. In both modes isolation of the two alarm inputs is initiated by applying the 2K2 resistor to the set input. In the non timed mode the isolation will remain until the set condition is removed (by either an open or closed circuit on the set input). In the timed mode the isolation will remain until the selected time matures or, optionally, until the set condition is removed as in the non timed mode.

While the isolation is active the buzzer sounds continuously until the last 15 seconds of the timed period (timed mode only) when the buzzer sounds intermittently.

If an attempt is made to remove the isolation manually while either of the two inputs are in alarm then the buzzer will sound intermittently until the fault is removed. The unit will remain in isolation mode until the fault is cleared or, if the timer is on, until the timer matures.

If timed mode is selected the unit will come out of isolation mode at the end of the selected period irrespective of the state of the two alarm inputs. In non timed mode the unit will remain isolated until the faults are cleared.

  • Relays 1 and 2 will follow the state of inputs 1 and 2 respectively being operated while the inputs are clear and released while the inputs are in alarm. While the unit is in isolation mode both relays remain operated irrespective of the state of the two inputs.
  • Relay 3 is released under normal operation and operated while the unit is in isolation mode.
  • Relay 4 will be operated while the unit is in isolation mode and will release if an alarm is detected on either of the two inputs. It will remain released until the set input is next activated (i.e. the open or short circuit is removed).

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