Automatic Transfer Switch

mbrooke

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Anyone know of a 15-35kv indoor automatic transfer switch? Were they ever made? Or do I need to use standard MV gear with breakers and VT cubicles?

Basically I have two sources and one transformer requiring an economical way to switch between the two.
 

mbrooke

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Jraef

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Once you get into 15kV class and up MV, open air break equipment gets a bit hairy, hence the use of VCBs. Then once you have VCBs, fault containment and isolation gets more important, hence the metal clad cubicles. So what the ATS mfrs really do here is to make an Automatic Transfer Controller (ATC) that uses regular MV switchgear as the power switching devices.
 

mbrooke

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Once you get into 15kV class and up MV, open air break equipment gets a bit hairy, hence the use of VCBs. Then once you have VCBs, fault containment and isolation gets more important, hence the metal clad cubicles. So what the ATS mfrs really do here is to make an Automatic Transfer Controller (ATC) that uses regular MV switchgear as the power switching devices.
What do you mean by hairy? :dunce:
 

Jraef

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As a general rule, air break switches at those voltage levels are “hairy” because of the arcing when they open and relatively catastrophic failure mode. S&C switches however have that “arcless” opening feature (that I’ve never totally understood), so that does make them somewhat different in their market. But that’s unique to them as far as I know so the other ATS mfrs would not be designing their MV ATS offerings around it.
 

mbrooke

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As a general rule, air break switches at those voltage levels are “hairy” because of the arcing when they open and relatively catastrophic failure mode. S&C switches however have that “arcless” opening feature (that I’ve never totally understood), so that does make them somewhat different in their market. But that’s unique to them as far as I know so the other ATS mfrs would not be designing their MV ATS offerings around it.
Thats what I have in mind. They can break full load- and I am confident in them because alduti and omni rupters are used on overhead gang operated switches without problem. I really like the concept, and to be frank I find breakers in an ATS application severe over kill. An MOD on an alduti rupter would be my choice IMHO.
 

Jraef

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Thats what I have in mind. They can break full load- and I am confident in them because alduti and omni rupters are used on overhead gang operated switches without problem. I really like the concept, and to be frank I find breakers in an ATS application severe over kill. An MOD on an alduti rupter would be my choice IMHO.
But does S&C offer it with a motorized operating mechanism option that can then be tied to an ATC? I've not worked with S&C much, I'm not familiar with their capabilities.
 

mbrooke

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But does S&C offer it with a motorized operating mechanism option that can then be tied to an ATC? I've not worked with S&C much, I'm not familiar with their capabilities.
They have an offer and a cheezey (being honest) controller. If I am not mistaken such a controller was behind the Super Bowl power outage years back.
 

mbrooke

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It failed as a 6000HP started. Why it failed we couldn't determine as there was nothing left off the switch.

To be honest, you would be better off (safer) with vacuum switches.
I believe you, you're right.

Just not sure how much more it will cost.
 

Tony S

Senior Member
What is a life worth?

I’ve been stood next to a 433V motor starter when it flashed over on shutdown, I needed new underwear! The back EMF caused the flashover between the starter’s 200A incoming fuses, this in turn took out the 550A busbar riser fuses.

Stopping a motor is often more precarious than starting………..?
 

mbrooke

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What is a life worth?

I’ve been stood next to a 433V motor starter when it flashed over on shutdown, I needed new underwear! The back EMF caused the flashover between the starter’s 200A incoming fuses, this in turn took out the 550A busbar riser fuses.

Stopping a motor is often more precarious than starting………..?
As long as no one opens the door when live (you should be qualified to even go near MV equipment) I can not see a problem with it using a switchgear enclosed air break switch.
 

Tony S

Senior Member
I’m a SAP (Senior Authorised Person), no way would I allow an electrician to open a live MV panel.

I do have master keys for interlocks, they’re in my safe at home not at work unless there’re needed.
 
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