Grounding of MV shields at one end only, other end floating at motor

[Dale001289]

Here's my scenario: We have 15kV induction motor with 3/C #2 shielded & ground, protected by a zero-sequence CT at the MCC bus (ANSI 50/51), two differential CT's (ANSI 87, one at MCC bus, one at motor termination box) and a fused contactor. GE Multilin SR469 provides motor protection, management and metering at the MCC vertical section.

To mitigate harmonics and circulating current, the client wants to leave cable shields 'floating' at the motor end and ground the shields at the bus only. He also wants to leave the EGC disconnected at the motor along with the shields. But isn't this a violation of 250.190?

 

[don_resqcapt19]

310.60(B)(1) implies that it is permitted to only connect the shield at one end.

There is nothing in the code that would permit you to eliminate the EGC connection at the motor.