OPERATION AND MAINTENANCE MANUAL
ID MOTORS
PAGE: 44
CODE: CTT52 EDITION: 03 RELEASE: APRIL 2019
Subject to technical changes without prior notice
5.2.3
Power cables
The inputs of the power cables that are to be connected on the motor terminal box strip and the converter terminals must comply
with current regulations. For the protection rating, type of cable-laying, allowed cable diameter, connection, etc., VASCAT
recommends the use of symmetrical structure screened cables in accordance with technical specification IEC TS 60034-25.
The cable screen must be made up of the maximum possible number of individual conductors and it must have good conductivity.
Twisted copper or aluminium screens are particularly suitable.
The screen connections must be made bearing in mind that they must cover a wide surface of the screen to create a 360°
contact using gland boxes for low impedance through a wide range of power levels. Make sure that the screen is HF (for high
frequencies). All the foregoing effectively reduces the voltages of the shaft and the housing, creating good derivation of the high
frequency currents. This will reduce the currents that will pass through the bearings. Consideration must be given to the fact that
the ends of the unscreened cable must be kept as short as possible.
The following two figures show the recommended terminations for screened cables:
Figure 11:
Recommended terminations
The connection between the power cable screen and the motor terminal box must be made using either of the two methods
shown in the following figures (on the left with an EMC gland seal and, on the right, with the screen connected to the terminal box
using a flange):
Figure 12:
Recommended connections in the terminal box
T
– Conductor material terminal box S – Cable screen
P
– Earth cable
M
– Motor body
Gs
– Conductor seals G – EMC gland seal F – Continuous Faraday box
Tb
– Terminal box Mt – Motor terminals
Et
– Earth terminal
S
– Cable screen
Sc
– Screen bracket G – EMC gland seal G1 – NON-EMC GLAND SEAL C - Cable
