General Information
August 2007 1-4 P/N 06-236716-001
1-4.2 Power Supply Unit
The power supply unit mounts behind the circuit board and operates from either 120 Vac 50/60
Hz or 240 Vac 50/60 Hz. It powers the system and also charges a standby battery set which
provides backup in case of loss of power from the AC source.
The battery charger is capable of charging sealed lead-acid 24 Vdc batteries of capacity up to
68 AH. The charge voltage is 27.4 Vdc nominal.
The actual battery capacity used for an application is a function of the units components,
devices and configuration. Refer to Appendix A for battery capacity calculations.
The power supply monitoring circuit provides a trouble signal if any of the following occur:
• Loss of AC input or if AC power falls below 85% of nominal. This causes an immediate
change-over to battery operation and a trouble signal after 30 seconds.
• Detection of a ground fault.
• Low charging current.
• High output voltage
The battery monitoring circuit provides a trouble signal if any of the following occur:
• The battery is installed backwards.
• The battery is disconnected.
• Battery voltage falls below 19.5 V (this condition causes the battery to disconnect and can
only be cleared when primary AC main power is restored).
1-4.3 Printed Circuit Board
The printed circuit board provides an interface or terminals for the following:
• Power Supply Unit
•Battery
• Initiating Device Circuits (System Inputs)
• System Outputs
• Operator Interface
• Auxiliary Power Output
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