Braid Grouding in Single Core Cables

[NickParker]

Refer to the attached typical grounding drawing,

Q1. Why Ground cables run along with power cables, if the power cables are of single core? Why not for Multi-core cables?
Q2. The braid (in the single core cable) not grounded in the HV Switchgear if it is feeding the HV motor (Hazardous area). Why not ground the braid in the HV Switchgear PE bus?
Q3. The braid (in the single core cable) is grounded in the HV Switchgear if it is feeding the Transformer. Why not ground the braid in the Transformer?

Thank you!

 

[waross]

1. Voltage is induced in a braid that is enclosing unbalanced currents. Grounding at more than one point results in a complete circuit in which an induced current will flow. This induced current causes heating and the conductor may need to be derated.
2. Additionally, the braid may not have adequate ampacity or withstand capacity to safely carry a fault current.
3. Reason #1 is the predominant reason.
Bill
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Ohm's law
Not just a good idea;
It's the LAW!