Chapter 1 IntroductionME300
1-6
Isolating main power from ground:
When the power distribution system for 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 the ground connection:
To ensure the safety of personnel, proper operation, and to reduce electromagnetic radiation, you must
properly ground the drive during installation.
The diameter of the cables must comply with the local safety regulations.
The shields of shielded cables must be connected to the ground of the drive to meet safety regulations.
The shields of shielded power cables can only be used as the ground for equipment when the above
points are met.
When installing more 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.
Pay particular attention to the following points:
Do not remove the RFI jumper while the power is on.
Removing the RFI jumper also disconnects 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.
Do not remove the RFI jumper 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.
Floating Ground System (IT Systems)
A floating ground system is also called an IT system, an ungrounded system, or a high
impedance/resistance (greater than 30 Ω) grounded system.
Disconnect the RFI jumper.
Check whether there is excess electromagnetic radiation affecting nearby low-voltage circuits.
In some situations, the transformer
and cable naturally provide enough EM radiation 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 security.
Do not install an external EMC filter. The EMC filter is connected to ground through the filter capacitors,
and connects the power input to ground. This is very dangerous and can easily damage the drive.
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