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 Post subject: maintenance
PostPosted: Sat Jun 04, 2011 5:38 am 

Joined: Sat May 01, 2010 2:20 am
Posts: 36
My question is about the term maintenance switch used to lower the ie on a Westinghouse switchgear[ 20yrs old or so]. Does most switchgear with a ats [for the backup gen ]that uses a plc to control each cb have a maintenance switch ? When would this be used? The cb are control electronically with trip setting.

IR testing showed a couple of possible loose connections on load side of breakers that needs to be corrected. There has not been a study on the switchgear. Plan on calling ec to look at this.


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PostPosted: Sat Jun 04, 2011 9:25 am 
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Joined: Mon Jun 02, 2008 11:58 am
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Location: Charlotte, NC
A "Maintenence switch" is a switch that is an accesory to a modern trip unit that is more a less a empory instanous trip setting. Usually you won't have an INST trip on a main breaker because it causes coordination issues with the feeders, so your ST trip has a delay that results in high Ei's on the switchgear (Protected by the main). A "maintnence switch" would be turned on (Reducing Ei) when a person needed to interact with the switchgear, rackout and locking out a feeder breaker for example.

These have become a very popular choice for mitigation, but you need to retrofit your breaker first if you have 20 year old gear. I am guessing you have Westinghouse DS breakers with eithwer an amptector or early digitrip trip unit. (If you have amptectors they probally should be retrofitted anyways). My shop does these everyday, we usually use AC PRO trip unit conversion kits and add the "Quick trip" if arc flash reduction is needed.


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PostPosted: Sat Jun 04, 2011 10:59 am 

Joined: Sat May 01, 2010 2:20 am
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Yes they have Westinghouse ds AND digtrips units would you think they have the quick trip?. They have long and short delay gfi pickup and similar settings.


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PostPosted: Sat Jun 04, 2011 12:07 pm 
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toolbbin wrote:
Yes they have Westinghouse ds AND digtrips units would you think they have the quick trip?. They have long and short delay gfi pickup and similar settings.


Some of the newer digitrips can use a maintnence switch, I think they have a direct modern replacement for your older digitrips that you can use a maintnence switch with, I would have to check on that. But, it is likely more expensive than going to AC PRO.


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PostPosted: Sat Jun 04, 2011 1:00 pm 

Joined: Sat May 01, 2010 2:20 am
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Thanks for the responses and load of knowledge with Westinghouse cb.


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PostPosted: Sat Jun 04, 2011 4:38 pm 
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Location: Charlotte, NC
toolbbin wrote:
Thanks for the responses and load of knowledge with Westinghouse cb.


You are welcome, holler at me if you ever have any issues with them


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