Honeywell Experion MX Operator's Manual page 42

Sensors with nuclear or X-ray radiation-based shutter controlled sources route the signal
through microswitches attached to the shutter closed positions.
Empty sensor positions, or sensors without radiation hazards, use a jumper in the wiring
harness to complete the circuit.
User panels pass the signal as well, requiring the last panel in line to utilize a jumper to
close the circuit.
Purpose:
The green light is used by personnel to ensure that radiation sensor shutters are safely
closed before work on the scanner heads is performed.
A head split key request by the user panel will be ignored if there is no current flow in the
green light circuit. Heads cannot be split without a green light showing all shutters closed.
The yellow switch indicator will light up when the switch is turned, but command might be
ignored if an unsafe condition exists, for example, when the green indicator is not on.
2.3.2.6 Circuit Protection
Description:
Electrical wiring is protected by overload through the use of current protection devices
including:
Purpose:
These devices limit current through the wiring, and limit the damage caused by overload
conditions due to wiring or circuit board faults.
A GFI (Residual Current Operated) circuit breaker is provided to protect against indirect
and direct contact by disconnecting hazardous high voltages caused by a short circuit.
The short circuit could be caused by unintentional contact with an exposed conductor. The
breaker disconnects with fault currents of less than 30 mA. This protects personnel from
dangerous physiological effects such as heart fibrillation.
2.3.2.7 Ground Connections
Description:
Specifically marked ground studs and wires connect the cabinets, panels, and hinged
cabinet doors at each end of the scanner to the scanner ground path.
•
Fuses
•
Positive temperature coefficient (PTC) auto resetting fuses
•
Breakers
• Ground Fault Interrupt (GFI) or Residual Current Operated breakers
6510020335
SCANNER SAFETY AND LOCAL CONTROLS
42