Vertiv | Liebert PEX+ Chilled Water | User Manual
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System Operation and Maintenance
5. Fasten all the electrical connection terminals.
6. Check whether the sockets and plugs are in good conditions. Replace those damaged ones.
7. If the power cables are damaged, to avoid further damage, the cables must be replaced by professional
personnel.
7.5. Appearance Inspection and Maintenance of Controller Components
A control section to make visual inspection of the following entries, and a simple function test process:
1. Visually inspect the power transformers and isolation transformers and test the output voltage of the indoor
unit and outdoor unit.
2. Check whether there are no signs of aging on the control interface board, control board, temperature and
humidity sensor board.
3. Clean the electrical control elements and control board of dust and dirt with brush and electronic dust
removing agent.
4. Check and fasten the I/O ports at the control interface board, including the connection between control board
and control interface board, as well as between the temperature/humidity sensor board and the interface
board. Check the connection between the user terminals (37# and 38#) and the control interface board.
5. Check the output connection between the control interface board and various contactors and the input
connection between control interface board and heating over-temperature protection switch, humidifier
protection switches, filter clogging switch, and airflow loss switch. In particular, check the connection parts
such as high-pressure switches and solenoid valves, and replace tIn particular, check the connection parts
such as water flow control valves, and replace the component if in poor connection or faulty.
6. Check and replace electrical components that are faulty, such as control fuses (or MCBs) and control boards.
7. Use temperature and humidity measuring meters with higher precision to measure and calibrate the
temperature and humidity sensors.
8. Adjust the setpoints. Check the action of the functional parts and the auto-flush control logic of water pan of
the infrared humidifier according to control logic.
9. Simulate and check the operation of the protection devices including high and low-pressure alarm, high and
low temperature alarm, high water level alarm and over-temperature protection.
10. Check the water detection sensor. Connect the water detection sensor probes and confirm the alarm through
the controller. The sensor should be placed in low-lying areas near the unit.
Set the humidity control mode to ‘relative humidity control during calibration process.
