Double Bus Bar switch gear

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mbrooke

mbrooke

Batteries Included
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United States
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Technician
What is double bus bar gear used for? Has anyone ever installed it or seen it in the field?

https://library.e.abb.com/public/22...04b9927/Leaflet_UG ZS1_DBB_Rev_2013_09_en.pdf


http://ms.schneider-electric.be/Main/PIX/catalogue/nrjed313574en.pdf


zdjecie34.jpg
 
mbrooke said:
How though? If buss A faults in the gear, wouldn't the arc flash also short out of damage the adjacent bus B?
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I didn't read the literature (I just looked at the pictures .. they speak to me), but I've heard they provide isolation barriers (this is SWGR construction) that limit single points of failure. Doesn't eliminate SPOF.
 
ron said:
I didn't read the literature (I just looked at the pictures .. they speak to me), but I've heard they provide isolation barriers (this is SWGR construction) that limit single points of failure. Doesn't eliminate SPOF.
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I see. Ever bump into such a beast?
 
ron said:
I have not. Generally if we need an A/B bus arrangement we provide a MTTM and do primary selective substations downstream.

Similar to what they propose but in a long version
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MTTM as in main-tie-main?

That is what makes sense to me. I can't see folding over the bus bar into the gear.
 
Double (paralleled) bus bars are used for increased ampacity. In our medium voltage (VCP-W) gear we use double bars for 3000A. 1200A & 2000A use single bars. This is done because of space constraints.
 
SG-1 said:
Double (paralleled) bus bars are used for increased ampacity. In our medium voltage (VCP-W) gear we use double bars for 3000A. 1200A & 2000A use single bars. This is done because of space constraints.
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But why offer isolating switches for each bus bar feeder take off?
 
mbrooke said:
MTTM as in main-tie-main?

That is what makes sense to me. I can't see folding over the bus bar into the gear.
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Main - Tie - Tie - Main

The Main - Tie is generally one lineup and the other Tie - Main is often in another room if they will let me.

The extra tie allows for [FONT=arial, sans-serif]Concurrent Maintainability leaving the tie (line and load) able to be serviced[/FONT]
 
ron said:
Main - Tie - Tie - Main

The Main - Tie is generally one lineup and the other Tie - Main is often in another room if they will let me.

The extra tie allows for Concurrent Maintainability leaving the tie (line and load) able to be serviced
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That and if a tie BF takes place you will not clear both bus bars.
 
SG-1 said:
The customer configures the switchgear for their requirements. If they need an isolating switch for safety purposes, say if the breakers are non-drawout then the gear is custom ordered that way.
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I mean that any breaker can select bus bar "A" or "B"
 
Just by looking at the picture, looks like a candidate for a primary feed to a maintenance bypass cabinet of some sort, enabling two sources of power either utility A and utility B with Kirk key interlocks to ensure that both sources are fed by the same incoming utility power and frequency. Concurrently, could also be used by an alternate source such as motor generators or SEP. To complement the comment re: increased ampacity, The busbars located in the bottom of the cabinet could be used for attaching an external load bank., thus the need for isolation and interlocks.


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Depending on the customer requirements some panels allow on load switching between busbars. Our dual busbar gear was used switch between either utility power or our own in house power. Normally they didn’t run coupled and so the A/B coupler switch had to include synchronising.
 
Tony S said:
Depending on the customer requirements some panels allow on load switching between busbars. Our dual busbar gear was used switch between either utility power or our own in house power. Normally they didn’t run coupled and so the A/B coupler switch had to include synchronising.
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How did you provide buss bar protection for these (if they had it)?
 
SG-1 said:
We have been talking about two different things. I thought you were asking why there are two bus bars per phase.

I now think you are asking why there are two buses ?

Tony S has your answer.
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yup, two busses but each breaker can select a bus bar:


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