SINAMICS

TN system : Earth fault protection for Sinamics S120

Thread Starter: Ajay Gupta   Started: 5/18/2012 12:30 PM   Replies: 1

  5/18/2012, 12:30 PM

Ajay Gupta Joined 4/28/2010 Last visit: 3/8/2013 Posts: 58 Rating:  (16)	(0)  Dear Friends, How can we implement earth fault protection for TN system (grounded system) in Sinamics S120 ? I have found that bender insulation monitor can only be connected in IT system. Can bender relay be used for TN systems or can we use some product from other manufacturer for earth fault protection ? Thanks. Regards   Ajay Gupta
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  6/19/2012, 11:09 AM

Ajay Gupta Joined 4/28/2010 Last visit: 3/8/2013 Posts: 58 Rating:  (16)

(0)  Dear Experts, We have connected 5 small motors at the output of the S120 motor module. Each motor is having a 3RV type MPCB before it. The customer demands that each motor should be protected against earth fault. Initially we designed the circuits using 3RB21 type of relays for each motor for earth fault detection. Now we found out that the 3RB21 relays can't be used at the output of the frequency converter (Siemens service support confirmed that this may cause nuisance tripping of the relays). Please suggest me some suitable device/module from Siemens or other manufacturer for detecting earth fault even at the output of the converters. Thanks & Regards Ajay Gupta

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