Leakage Current And Residual Current Device (Rcd) - INVT Goodrive300-01A Series Operation Manual

Goodrive300-01A series VFD for air compressor
Solutions:

Check and confirm the abnormal signal cable is routed with motor cable motor cable at a
distance of at least 20cm.

Connect in parallel the digital input terminal (S) used for start/stop control with other idle digital
input terminals. For instance, S1 terminal is used for start/stop control, S4 terminal is idled,
then try to short connect S1 terminal with S4 terminal.
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
Low cost, high
vulnerable to voltage fluctuation of the grid
and ambient
anti-interference capacity
Solution to mal-operation of RCD (on the part of VFD)
Try to disassemble the jumper cap in "EMC/J10".
a)
b) Try to decrease the carrier frequency to 1.5kHz (P00.14=1.5).
Try to change the modulation mode to "3PH modulation and 2PH modulation" (P8.40=00).
c)
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.
sensitivity, small
temperature, weak
Common EMC problems and troubleshooting
Electromagnetic RCD
Require the
transformer to be quite sensitive, precise and
size,
stable, made from permalloy material with
high permeability, complicated process and
high cost, immune to voltage fluctuation of the
grid and
anti-interference capacity
-179-
zero sequence
ambient temperature.,
current
strong