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 Post subject: Selector Switch / Pushbutton for Maintenance Mode
PostPosted: Thu Jul 06, 2017 12:21 pm 

Joined: Thu Jul 06, 2017 9:19 am
Posts: 12
Hi folks,

I'm not a switchgear guy or technician by any means.

I wanted to know if there are selector switches / push buttons with lights that can be used to activate maintenance mode on a relay to lower the overcurrent settings to lower incident energy levels.

I've tried googling, but I'm not finding part #s or model #s for devices that come with a built-in light to indicate maintenance mode is activated....


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 Post subject: Re: Selector Switch / Pushbutton for Maintenance Mode
PostPosted: Fri Jul 07, 2017 9:47 am 
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Joined: Tue Jan 13, 2009 5:00 pm
Posts: 626
Try Electroswitch or Schweitzer. While you can use a set of contacts off the switch to control the light, the best option is to use an output from the protective relay to light the light. This assumes you have a microprocessor relay with programmable outputs.


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 Post subject: Re: Selector Switch / Pushbutton for Maintenance Mode
PostPosted: Fri Jul 07, 2017 2:02 pm 
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Joined: Mon Jan 18, 2010 11:35 am
Posts: 604
Location: Wisconsin
mbk.2k3 wrote:
I wanted to know if there are selector switches / push buttons with lights that can be used to activate maintenance mode on a relay to lower the overcurrent settings to lower incident energy levels.


Several equipment manufacturers simply use illuminated selector switches, the 30mm size, like those found on industrial control panels. You can get padlock attachments for them to prevent in inadvertent operation.
The last one I used was from Schneider Electric - 9001K11J35LL.


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 Post subject: Re: Selector Switch / Pushbutton for Maintenance Mode
PostPosted: Fri Jul 07, 2017 7:17 pm 
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Joined: Tue Oct 26, 2010 9:08 am
Posts: 2178
Location: North Carolina
If you can't spare an output (not a great situation) use a selector switch or a maintained push button that is illuminated with two contact blocks. Wire power for the pilot light in series with the second contact block so it indicates status. Electroswitch is more of the T-handle things that is popular as a maintained/flag function but using it adds at least one full cycle to timing, increasing incident energy. These days it's better to fire the shiny trip on D.C. directly off the protection relay, so trip times are minimized.


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 Post subject: Re: Selector Switch / Pushbutton for Maintenance Mode
PostPosted: Mon Jul 10, 2017 7:53 am 
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Joined: Fri Apr 15, 2011 7:43 am
Posts: 178
Location: Colorado
There are actually a couple of different approaches. First you need to know if you can add a maintenance switch. If the relay and breaker are separate this is generally the only way. If the relay is integral to the breaker (480V power breaker) then adding a switch may not be possible without a lot of time and money.

If you have a separated relay/breaker then a switch may (is there is a spare input) be added. That being said, it may be possible to use the built in switches on the relay to set a maintenance mode without external switches/lights. In any case it will require a relay engineer to configure the relay, design the controls wiring, and get the settings.


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 Post subject: Re: Selector Switch / Pushbutton for Maintenance Mode
PostPosted: Mon Jul 10, 2017 8:37 am 
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Joined: Tue Jan 13, 2009 5:00 pm
Posts: 626
To be clear: Using an Electroswitch or any other brand of lockout relay to control the trip circuit to the breaker adds to the clearing time. Using an Electoswitch or another brand of manual switch to signal the protective relay to trip instantaneously will shorten clearing time.


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 Post subject: Re: Selector Switch / Pushbutton for Maintenance Mode
PostPosted: Mon Jul 10, 2017 10:50 am 
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Joined: Tue Oct 09, 2012 5:00 pm
Posts: 52
Among many technology & mechanism to reduce arc flash incident energy, I have used the following three devices:
1. SEL 751A: This is a microprocessor based relay that trips the breaker based on light and fault current. It works on "AND" logic-meaning the relay had to sense both light and fault current to trip the breaker. The beauty about this relay is both the intensity of light and magnitude of fault current is configurable. And there is no maintenance switch. As long as the fiber optic point sensor and loop sensors are positioned correctly, it will detect arc flash and trip the breaker in the event of an arc flash.
2. Eaton's ARMS (Arcflash Reduction Maintenance Switch): There are two types. One is fixed (non-adjustable) and the other is adjustable (R1-R5). It has a two position selector switch-Normal Mode and Maintenance Mode.
3. Schneider's AMS (Alternate Maintenance Setting Switch): This also has two position switch for Maintenance "ON" and "OFF".
While these sophisticated devices can reduce incident energy, let a qualified engineer perform the analysis first and get a recommendation. Because depending on the actual short circuit available from the utility, sometimes this high end device can just sit there & may not reduce the incident energy to the level that you expect, given its price tag. Also NEC 240.87 requirements have changed in 2017 edition. With the later two switches, training qualified workers and integrating the operation sequence of the switch in the electrical safety program is crucial. If live work (permit per latest NFPA 70E is required) is performed without selecting maintenance mode, it defeats the purpose and can lead to dangerous consequences.


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