Chapter 1 IntroductionC2000 Plus
1-7
Isolating main power from ground:
When the power distribution system of the drive is a floating ground system (IT Systems) or an asymmetric
ground system (Corner Grounded TN Systems), you must remove the RFI jumper. Removing the RFI
jumper disconnects the internal capacitors from ground to avoid damaging the internal circuits and to
reduce the ground leakage current.
Important points regarding ground connection
To ensure the safety of personnel, proper operation, and to reduce electromagnetic radiation, you must
properly ground the motor and drive during installation.
The diameter of the grounding cables must comply with the local safety regulations.
You must connect the shielded cable to the motor drive’s ground to meet safety regulations.
Only use the shielded cable as the ground for equipment when the aforementioned points are met.
When installing multiple drives, do not connect the grounds of the drives in series but connect each
drive to ground. The following pictures show the correct and wrong ways to connect the grounds.
Figure 1-8 Figure 1-9
Pay particular attention to the following points:
Do not remove the RFI jumper while the power is ON.
Removing the RFI jumper also cuts the capacitor conductivity of the surge absorber to ground and the
built-in EMC filter capacitors. Compliance with the EMC specifications is no longer guaranteed.
Do not remove the RFI jumper if the mains power is a symmetrical grounded power system in order to
maintain the efficiency for EMC circuit.
Remove the RFI jumper when conducting high voltage tests. When conducting a high voltage test to
the entire facility, disconnect the mains power and the motor if the leakage current is too high.
Floating Ground System (IT Systems)
A floating ground system is also called IT system, ungrounded system, or high impedance / resistance
(greater than 30Ω) grounding system.
Remove the RFI jumper to disconnect the ground cable from the internal filter capacitor and surge
absorber.
In situations where EMC is required, check for excess electromagnetic radiation affecting nearby
low-voltage circuits. In some situations, the adapter and cable naturally provide enough suppression. If
in doubt, install an extra electrostatic shielded cable on the power supply side between the main circuit
and the control terminals to increase shielding.
Do not install an external RFI / EMC filter. The external EMC filter passes through a filter capacitor and
connects power input to the ground. This is very dangerous and damages the motor drive.
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