Read Before Test Run - Mitsubishi Electric PURY-HP72 Service Handbook

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[6-1 Read before Test Run ]


Read before Test Run

6 Test Run
(1) Check for refrigerant leak and loose cables and connectors.
(2) When opening or closing the front panel of the control box, do not let it come into contact with any of the internal
Before inspecting the inside of the control box, turn off the power, keep the unit off for at least 10 minutes, and confirm that
the capacitor voltage (inverter main circuit) has dropped to 20 VDC or less. (It takes about 10 minutes to discharge electricity
after the power supply is turned off.)
Control box houses high temperature parts. Be well careful even after turning off the power source.
Perform the service after disconnecting the outdoor unit fan board connector (CNINV) and the inverter board connector (CN1).
(To plug or unplugconnectors, check that the outdoor unit fan is not rotating and that the voltage of capacitor in the main circuit
is 20 VDC or below. The capacitor may collect a charge and cause an electric shock when the outdoor unit fan rotates in windy
conditions. Refer to the wiring nameplate for details.)
To connect wiring to TB7, check that the voltage is 20 VDC or below.
Reconnect the connector (CNINV) back to the fan board and reconnect the connector (CN1) back to the inverter board after
(3) Measure the insulation resistance between the power supply terminal block and the ground with a 500V megger and
make sure it reads at least 1.0Mohm.
Do not operate the unit if the insulation resistance is below 1.0Mohm.
Do not apply megger voltage to the terminal block for transmission line. Doing so will damage the controller board.
The insulation resistance between the power supply terminal block and the ground could go down to close to 1Mohm imme-
diately after installation or when the power is kept off for an extended period of time because of the accumulation of refrigerant
in the compressor.
If insulation resistance reads at least 1 MΩ, by turning on the main power and keeping it on for at least 12 hours, the refrigerant
in the compressor will evaporate and the insulation resistance will go up.
Do not measure the insulation resistance of the terminal block for transmission line for the unit remote controller.
(4) When the power is turned on, the compressor is energized even while it is not operating.
Before turning on the power, disconnect all power supply wires from the compressor terminal block, and measure the insula-
tion resistance of the compressor.
Check the compressor for a ground fault. If the insulation resistance is 1.0 MΩ or below, connect all power supply wires to
the compressor and turn on the power to the outdoor unit. (The liquid refrigerant in the compressor will evaporate by energiz-
ing the compressor.)
(5) Make sure the valves on both the high-pressure and low-pressure sides are fully open.
Securely tighten the cap.
(6) Check the phase sequence and the voltage of the power supply.
When the voltage is out of the ±10% range, or when the phase voltage difference is more than 2%, please discuss the coun-
termeasure with the customer.
(7) [When a transmission booster is connected]
Turn on the transmission booster before turning on the outdoor units.
If the outdoor units are turned on first, the connection information for the refrigerant circuit may not be properly recognized.
In case the outdoor units are turned on before the transmission booster is turned on, perform a power reset on the outdoor
units after turning on the power booster.
(8) Turn on the main power at least 12 hours before test run.
Insufficient powering time may result in compressor damage.
(9) When a power supply unit is connected to the transmission line for centralized control(*), perform a test run with the
power supply unit being energized. Leave the power jumper connector on CN41 as it is (factory setting).
*Includes the cases where power is supplied to the transmission line from a system controller with a power-supply function
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