Test Run; Before A Test Run - Mitsubishi Electric m-MOCU-G02-050 Installation Manual

11. Test run

11-1. Before a test run

After the wiring work has been completed, measure the insulation resistance, and make
sure that it reads at least 1 MΩ.
- Failure to do so may result in electric leakage, malfunction, or fire.
Turn on the power at least 12 hours before starting operation. Keep the power turned on
throughout the operating season.
- Insufficient energizing will result in malfunction.
・Before performing a test run, turn off the power to the outdoor unit, and disconnect the power cable from the power
supply terminal block to measure the insulation resistance.
・Measure the insulation resistance between the power supply terminal block and the earth with a 500 V ohmmeter,
and make sure it is at least 1 MΩ.
・Turn on the indoor unit before turning on the power to the outdoor unit.
・If the insulation resistance is 1 MΩ or above, connect the power cable to the power supply terminal, and turn on the
power at least 12 hours before starting operation. If the insulation resistance is below 1 MΩ, do not operate the unit,
and check the compressor for a earth fault.
・While the unit is turned on, the compressor will remain energized even when it is stopped.
・The insulation resistance between the power supply terminal block and the earth may drop to near 1 MΩ
immediately after installation or when the main power to the unit has been turned off for a long time because of the
stagnation of refrigerant in the compressor.
・By turning on the main power and energizing the unit for 12 hours or longer, the refrigerant in the compressor will
evaporate and the insulation resistance will rise.
・Do not apply an ohmmeter voltage to the terminal block for transmission cables. Doing so will damage the control
board.
・Do not measure the insulation resistance of the transmission terminal block of the unit remote controller.
・Check for refrigerant leakage and for loose power cables and transmission cables.
・Check that the liquid and gas side service valves are fully open. Tighten the valve caps.
・Check the phase order of the power supply and the interphase voltage. If the voltage is out of the ±10% range, or if
the voltage imbalance is more than 2%, discuss the countermeasure with the customer.
・When power is turned on or after power recovery, performance may degrade for approximately 30 minutes.
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