Delta Compact Drive MS300 IP66/NEMA 4X Series User Manual page 16

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 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 (Figure 1-13 and Figure 1-14) 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.
 Remove the RFI jumper to cut off the connection between the grounded internal filter capacitor and
the surge absorber to the ground.
 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.
Figure 1-13
Chapter 1 IntroductionMS300 (IP66 / NEMA 4X)
1-9
Figure 1-14