PE Cable placement in cable ladder 1

[Jensdsds]

Hello

In a system with a large motor supplied by a converter.
The cabling is three phase with a PE conductor.

In the cable tray/ladder from the converter to the motor, Where should the PE conductor be placed?

As close the phase cables as possible, in the same cable tray as the cables, or as far way from the phase cable to prevent induced voltage in the PE cable.

From

https://www.electrical-installation..._and_choice_for_protective_earthing_conductor

i can read that:
"In IT and TN-earthed schemes it is strongly recommended that PE conductors should be installed in close proximity (i.e. in the same conduits, on the same cable tray, etc.) as the live cables of the related circuit. This arrangement ensures the minimum possible inductive reactance in the earth-fault current carrying circuits."

Should this prioritized, and thereby ignore the losses induced in the PE cable at nominal run?

 

[waross]

Ignore the losses and put the PE as close as possible.
I remember seeing a recommended cable construction for VFD condustors.
It was 7 core cable. The center core was a PE and the surrounding cores were arranged; PE, A, PE, B, PE, C.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Jensdsds]

Thats what i thougt thanks.

The losses wont affect the current in the phase cables right?
It will only be dissipated as heat in the PE cable, which should be able to withstand it?

 

[waross]

The losses are related to frequency. The higher order harmonics tend to induce more current in the PE.
But the higher order harmonics tend to be lower amplitude and trapping some of the harmonically induced losses in the cable somewhat mitigates the losses due to harmonics in the motor.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Jensdsds]

Thanks for your answer,

So as i understand it, the losses gained from laying the PE close to the phase cables will almost never outweigh the gained harmonics/common mode reduction?

 

[waross]

I am going to wait awhile and see if jraef comments.

Bill
--------------------
Ohm's law
Not just a good idea;
It's the LAW!