T1689 Technical Manual Rev 07 PDS Design
MV3000 Air Cooled DELTA Protection of Cables Routed Outside the Enclosure
Page 107
DC Link +
DC Link -
R
R
Earth Fault
Current Sensor
Figure 4–2. – DC Link Earth Referencing
• The resistance value should be chosen to suitably limit the current to earth during fault
conditions. A value of 1 kΩ per resistor is commonly used.
• A current sensor placed around the wire between the resistor and earth will detect an earth fault
anywhere in the system.
• Only the live conductors should pass through the current sensor. Earth wires, cable screens, and
armours should not be passed through the sensor.
• The current sensor must be capable of detecting DC as well as AC.
If earth fault monitoring is to be used, only one system should be installed. Multiple earth fault monitoring
systems can interfere with each other.
4.6 PROTECTION OF CABLES ROUTED OUTSIDE THE ENCLOSURE
All cables which are routed outside the drive enclosure - e.g. plant wiring where there is a requirement for
screening, segregation, terminations etc. - require protection which would normally be determined by the
application but generally follow the rules already described in this section.
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