INVT Goodrive300-01A Series, Руководство по эксплуатации

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Goodrive300-01A series VFD for air compressor Common EMC problems and troubleshooting
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E.4 Leakage current and residual current device (RCD)
As the VFD outputs high frequency PWM voltage to drive the motor, the distributed capacitance
against the radiator from internal IGBT and between rotor and stator of the motor may cause the VFD
to generate high frequency leakage current against the ground. While the RCD is used to detect the
power frequency leakage current when grounding fault occurred to electrical circuit, the application of
VFD may cause mal-operation of RCD.
How to select RCD:
Due to the specialty of VFD system, it is required that the rated residual operating current should be
above 200mA for regular RCDs at all levels, and the VFD must be grounded with proper technics.
As for the setting time of RCD, the time limit of preceding action should be longer than the secondary
action and time gap between them should be set to a value larger than 20ms e.g. 1s, 0.5s and 0.2s.
It is recommended to use electromagnetic RCD for the electrical circuit of VFD system. Such RCD
carries strong anti-interference capacity to prevent the RCD from being affected by high frequency
leakage current.
Electronic RCD Electromagnetic RCD
Low cost, high sensitivity, small size,
vulnerable to voltage fluctuation of
the grid and ambient temperature,
weak anti-interference capacity
Require the zero sequence current transformer to be quite
sensitive, precise and stable, made from permalloy
material with high permeability, complicated process and
high cost, immune to voltage fluctuation of the grid and
ambient temperature., strong anti-interference capacity
Solution to mal-operation of RCD (on the part of VFD)
a)
Try to disassemble the jumper cap in “EMC/J10” (refer to section 3.1.3 and 3.1.4 for the position
of J10)
b) Try to decrease the carrier frequency to 1.5kHz (P00.14=1.5);
c)
Try to change the modulation mode to “3PH modulation and 2PH modulation” (P8.40=00)
Solution to mal-operation of RCD (on the part of system distribution)
a) Check and confirm the power cable is not immersed in water
b) Check and confirm the cable is not broken or switched over;
c) Check and confirm if secondary grounding occurred to the null line;
d) Check and confirm if power cable terminal is in the air switch or the contactor is poorly contacted
(loose screws);
e) Check the single-phase electric equipment and confirm if the ground line is misused as null line;
f) VFD power cable and motor cable should not be shielded ones.
Leakage protection of motor autotuning
During motor autotuning, the measurement on differing motor parameters is conducted step by step,