single core AC cables termination 1

[simisteven]

We are installing a 160kW VSD in a substation. I notice that contractors have routed the 6 single core flexible cables to the VSD through a steel gland plate. To my knowledge this is a NO NO because of inductance and eddy currents.
any Comments?
PS For such installations what size should the earth cable be? Minimum 50% of main conductor size is my guess?

 

[waross]

I agree that that is not good practice, although it may be allowed under Canadian code depending on the current. The Canadian code prohibits the entry of a single conductor through a ferrous plate when the current in the conductor is greater than 200 Amps. At 380 Volts or 480 Volts the current in the individual conductors will be below 200 Amps.
And notwithstanding single conductor cables may enter a ferrous plate if the plate is properly slotted so that each group of three holes is effectively one hole and non-ferrous gland connectors and locknuts are used.. If conducting plates are used at each end of the cable run, provision must be made to interrupt sheath and/or armour currents or the cables must be de-rated.
Note: These are code requirements under the Canadian code. Your codes may differ.

Bill
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"Why not the best?"
Jimmy Carter