Chapter 2. Wiring | VFD-VJ
2-9
2-1-1 Grounding Short-Circuit Plate Description (RFI Switch)
RFI switch
The drive contains Varistors / MOVs that are connected from phase to phase and from phase to ground to
protect the drive against mains surges or voltage spikes.
Because the Varistors/MOVs from phase to ground are connected to ground with the RFI switch, removing
the RFI jumper disables the protection.
The RFI switch also connects the filter capacitors to ground from a return path for high frequency noise to
isolate the noise from contaminating the mains power. Removing the RFI switch strongly reduces this
protection.
Isolating main power from ground
When the power distribution system of the drive is a floating ground system (IT Systems) or a TT system
(Terre-Terre en français, or earth-earth in English), you must remove the RFI switch. Removing the RFI
switch disconnects the internal capacitors from ground to avoid damaging the internal circuits and to
reduce the ground leakage current (in accordance with IEC61800-3 regulation). The RFI switch is shown in
the images below.
RFI Switch on the motor drive Removable RFI Switch
NOTE:
Do not remove the RFI switch while the power is on.
Efficient galvanic isolation is no longer guaranteed if removing the RFI switch. Then all the input
and output terminals are low voltage terminals which have basic isolation. Removing the RFI switch
also reduces the compliance with the EMC specification.
Do not remove the RFI switch while conducting high voltage tests. When conducting a high
voltage test to the entire facility, you must disconnect the mains power and the motor if the leakage
current is too high
Do not switch off the RFI switch when the main power is a grounded power system. To prevent
motor drive damage, the RFI switch shall be removed if the motor drive is installed on an ungrounded
power system, a high resistance-grounded (over 30 ohms) power system, or a corner grounded TN
system.
To Next Page
Loading...
Need help?
General
