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Topic Title: Drives tripping generator when coming on load after 2 minutes.
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Created On: 08 August 2012 07:31 PM
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 08 August 2012 07:31 PM
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rbridge1988

Posts: 10
Joined: 06 March 2012

Hi there,

got a site pumping treated water with a duty/standby setup and a backup generator for mains failures. There was 2 siemens VSD micromaster 440's one for each pump controlling on a PID feedback. When the mains was failing on high demand though and the duty drive ran above 46 Hz it would trip the generator out.

We have remedied the fault by changing them to ABB ACS550's and not a problem. I know the fault it down to power filtering but what exactly causes it? The generator was operating an RCD type protection but i'm still a bit unsure why it took 2 minutes to trip out and high demand on the VSD.
 09 August 2012 09:00 AM
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JohnLindop

Posts: 15
Joined: 30 October 2004

Hello,

The VSD has an EMC filter built in which uses ground as a drain for any electrical noice. An RCD is designed to trip on leakage to ground. Hence the problem. The Siemens 440 manual gives advise on which RCD's may be used with the drive. But you cannot have more then one VSD per RCD. Best rule of thumb is to remove the RCD from the circuit. It would not be time related but dependant on the amount of earth leakage from the EMC filter.
 09 August 2012 09:00 AM
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JohnLindop

Posts: 15
Joined: 30 October 2004

Hello,

The VSD has an EMC filter built in which uses ground as a drain for any electrical noice. An RCD is designed to trip on leakage to ground. Hence the problem. The Siemens 440 manual gives advise on which RCD's may be used with the drive. But you cannot have more then one VSD per RCD. Best rule of thumb is to remove the RCD from the circuit. It would not be time related but dependant on the amount of earth leakage from the EMC filter.
 09 August 2012 09:00 AM
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JohnLindop

Posts: 15
Joined: 30 October 2004

Hello,

The VSD has an EMC filter built in which uses ground as a drain for any electrical noice. An RCD is designed to trip on leakage to ground. Hence the problem. The Siemens 440 manual gives advise on which RCD's may be used with the drive. But you cannot have more then one VSD per RCD. Best rule of thumb is to remove the RCD from the circuit. It would not be time related but dependant on the amount of earth leakage from the EMC filter.
 14 August 2012 08:35 PM
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rbridge1988

Posts: 10
Joined: 06 March 2012

Siemens don't give advice, we phoned the technical helpline and were no use. APDS Bristol for ABB VSD's. I won't be touching Siemens with a barge pole. No way to disconnect the Filter on a Siemens VSD (ABB has 2 screws) to prove it so splashed out on a VSd and it's worked luckily. We have other sites with 440's and a generator which run with no problems.
 24 August 2012 08:35 AM
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JohnLindop

Posts: 15
Joined: 30 October 2004

You can disconnect the filter by cutting a wire or link, Siemens in Manchester should be able to help as this needs doing for drives working in USA. I think its type B RCD's that are OK. Anyway you have fixed the problem.
Best of luck with the 440's.
 18 September 2012 10:14 AM
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Avatar for chrissj91.
chrissj91

Posts: 18
Joined: 26 October 2011

Howdy,

Speak to Andy Williams at Siemens in Manchester.
He has worked with us on plenty of projects and is probably the most helpful man you will encounter.
And the Micromaster range doesn't usually come with a filter as standard, its user specified on purchase. So you may not have one at all.
We had a similar problem with one of our plants in the early days, it turned out that because we had lots of inverters with no filtering, harmonics were going through the roof and knocking everything off.

Hope that helps somewhat.

Chris

-------------------------
Christopher Jones

Linked In - http://www.linkedin.com/in/chrissj91
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