Grounding, Cabling, And Shielding Recommendations - Siemens SINAMICS PERFECT HARMONY GH180 Operating Instructions Manual

7.3

Grounding, Cabling, and Shielding Recommendations

NOTICE
Adherence to Local Safety Regulations
Understand and obey all local safety regulations with regards to grounding.
Recommendations do not supersede safety grounding regulations.
VFD Grounding
The variable frequency drive as a whole should be bonded to the facility ground using
the following two methods:
● Bond the VFD at one point only using the shortest cable length. The VFD cabinet to facility
ground connection shall be properly sized per local codes or regulations.
– The connection can be made in the VFD either in the input cabinetry or in the output
– In the event of ground faults, the peak current and duration are much greater for the
● If a grounding grid is available under the VFD, the VFD cabinet can be solidly grounded to
the facility ground structure at multiple points.
Neither the SINAMICS PERFECT HARMONY GH180 transformer primary neutral point on the
input, nor the medium voltage output neutral point, shall be bonded to ground.
If used, the precharge winding shall be resistance grounded.
Motor Grounding
The motor case must be bonded to facility ground using the shortest cable length.
Bearing Currents:
● If machine induced bearing currents are of concern, then isolated bearings on the non-drive
end of the motor shaft can be implemented
● Siemens recommends using a shaft ground brush on the drive-end of the motor shaft when
concerns exist regarding whether the rotating load or the drive could cause harmful bearing
currents.
● The encoder must be electrically isolated from the motor shaft.
Air Cooled 6SR5
Operating Instructions, 07/2018, A5E42736645A_AB
cabinet.
input than the output. Therefore, it is preferable to ground the VFD in the input cabinet
to minimized the fault current flowing through the cabinet to cabinet connections.
7.3 Grounding, Cabling, and Shielding Recommendations
Electrical Connections
59