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Only for training and service purposes
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Checking Key Components of Unit
1.5 Compressor
Check and ensure in following order when error related with the compressor or error related with power occurs
during operation:
[Cautions when measuring voltage and current of inverter power circuit]
Measuring values may be different depending on measuring tools and measuring circuits since voltage, current in
the power supply or output side of the inverter has no same waveform.
Especially, output voltage changes when output voltage of the inverter has a pattern of pulse wave.
In addition, measuring values appear largely different depending on measuring tools.
Note
1) If using a portable tester when checking the output voltage of the inverter is constant (when comparing relative
voltage between lines), always use an analog tester. Especially exercise particular caution if the output frequen-
cy of the inverter is low, when using a movable tester, where change of measured voltage values is large
between other lines, when virtually same values appear actually or where there is danger to determine that fail-
ure of the inverter occurred.
2) You can use rectification voltmeter ( ) if using commercial frequency tester when measuring output values of
the inverter (when measuring absolute values). Accurate measuring values cannot be obtained with a general
portaable tester (For analog and digital mode).
1
2
Is how long power on during
operation?
Does failure appears again
when starting operation?
Method to measure insulation
resistance
Method to measure coil
resistance
1) Power on for 12 hours or more
2) Power on for 12 hours or less
1) The compressor stops andsame
error appears again.
2) If output voltage of the inverter is
stable.
3) If output voltage of the inverter is
unstable or it is 0 V.
(When incapable of using a digi-
tal tester)
• Go to No.2.
• Go to No.2 after applying
power for designated time (12
hours).
• Check IPM may fail.
• Check coil resistor and insula-
tion resistor. If normal, restart
the unit. If same symptom
occurs, replace the compres-
sor.
• Insulation resistor: 2 MΩ or
more
• Coil resistor:
• Check the IPM.
If the IPM is normal, replace
the inverter board.
• Check coil resistor and insula-
tion resistor.
No. Checking Item Symptom Countermeasure
Inverter (NPT525DAA)
U-V 1.183
U-W 1.174
V-W 1.181
at 25 °C
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