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Component Operation and Maintenance, Checks and Adjustments
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7.1.2 Electric Panel
The electric panel should be inspected for any loose electrical connections.
Control Transformer and Fuses
The control system is divided into four (4) separate circuits. Fuses located on the transformer/fuse
board individually protect the control voltage circuits. If any of the fuses are blown, first eliminate
shorts, then use spare fuses supplied with unit. Use only type and size of fuse specified for your unit.
The small isolation transformer on the main control board supplies 24 volts to the electronics. The
transformer is internally protected. If the internal protector opens, the transformer/fuse board must
be replaced. Also check the control voltage fuse on the main control board before replacing the trans-
former/fuse board.
Fan Safety Switch
For Deluxe units, the Fan Safety Switch is located in the low voltage compartment and consists of a
diaphragm switch and interconnecting tubing to the blower scroll. The Fan Safety switch is wired
directly to the control circuit to deactivate the unit and activate the alarm system if airflow is inter-
rupted.
Firestat
The optional firestat is a bimetal operated sensing device with a Normally Closed switch. This device
will shut down the entire unit when the inlet air temperature exceeds a preset point. It is connected
between terminals 1 and 2 at plug P39.
Smoke Detector
The optional smoke detector power supply is located on the base of the upflow units, and at the top of
downflow units. It is constantly sampling return air through a tube. No adjustments are required.
Water Detection Sensor
Liebert manufactures a variety of water-detection systems, including point, zone and cable systems.
Follow the instructions supplied with your selected device for proper installation, adjustment and
maintenance.
Remote Shutdown
A connection point is provided for customer-supplied remote shutdown devices. Terminals 37 and 38
on the terminal strip are jumpered when no remote shutdown device is installed. Refer to the unit’s
electrical schematic and the unit’s installation manual.
!
WARNING
Be sure that power to the unit is shut down before attempting to tighten any fittings or
connections.
!
CAUTION
Do not use near flammable liquids or for flammable liquid detection.