Gear Temp

A

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
What is load shedding and would it apply to this situation? I believe I have heard it before and it means obviously shedding/reducing loads I guess We have a large 3000a piece of gear that needs temping out. The GC responding by saying .....temping out this gear will be an important discussion as there may not be a lot of load shedding and there are only two spare 200 amp switches in the adjacent gear.
Okay I understand what he's saying by only having to spare 200 amp switches... he means that we don't have enough power to Temp out the gear. What does he mean by load shedding and how does that come into play in temping out the gear.
If there is not enough available power to temp out the gear I guess the only other option is a generator?
 
Alwayslearningelec said:
The GC responding by saying .....temping out this gear will be an important discussion as there may not be a lot of load shedding and there are only two spare 200 amp switches in the adjacent gear.
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Who knows what that means in this context. Load shedding often refers to removing some load from an alternate power source like a generator where the generator is not large enough to carry the entire connected load.
 
Interpretation:
A 220 cakculation to see two 200A switches enough for actual load, fed temp from 3000A gear without much load shedding
 
I don't see any other way to temp out this 3000A board while we replace switch with breaker except to use a temp generator. There are not spare switches in any nearby gear that would be able to provide 3000A or close.

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Alwayslearningelec said:
I don't see any other way to temp out this 3000A board while we replace switch with breaker except to use a temp generator. There are not spare switches in any nearby gear that would be able to provide 3000A or close.

View attachment 2580164
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Are you replacing the 2500 amp OCPD? Can you temp out on the load side of the 2000 amp switch? You could then lock that switch in the open position which would de-energize the 2500 OCPD.
 
infinity said:
Are you replacing the 2500 amp OCPD? Can you temp out on the load side of the 2000 amp switch? You could then lock that switch in the open position which would de-energize the 2500 OCPD.
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What do you mean temp out the LOAD side? Wouldn't the LINE side be temp'ed out? But then temping out the LINE side would still leave the 2500A that we are working on live? Ok if that's right I got it. How do you temp out the load side of that switch?
 
Alwayslearningelec said:
What do you mean temp out the LOAD side? Wouldn't the LINE side be temp'ed out? But then temping out the LINE side would still leave the 2500A that we are working on live? Ok if that's right I got it. How do you temp out the load side of that switch?
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Look at the one line. If you connected the temp on the fuse side (load side) of the 2000 amp switch you can de-energize the feed to the 2500 amp OCPD. Just lock the 2000 amp switch in the open position so it cannot be back fed by the temporary feeder.
 
In my opinion this is all design that should be done by the electrical engineer. The engineer needs to specify the source of the temporary power source and the connection points.
The first thing the engineer needs to know is the actual load served by the 2000 amp fused switch. The second thing would be to determine how long those loads can be down while connecting the temporary power source. The last thing would be for the engineer to determine the exact points of connection for the temporary power source. If that switchgear is all bus bar a point of connection for the temporary source may be difficult to find without bus modifications.
I would expect that the temporary power source is going to have to be a generator.
 
Alwayslearningelec said:
what exactly are you stating?
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Well you revealed later post 2500A switch replacement by 3000A breaker and single line diagram. You earlier state two 200A spare switches available and so I thought with 220 calculation and load shedding, it may be checked the two 200 A spare switches enough to temp supply the actual load during 2500A switch replacement.
 
don_resqcapt19 said:
In my opinion this is all design that should be done by the electrical engineer. The engineer needs to specify the source of the temporary power source and the connection points.
The first thing the engineer needs to know is the actual load served by the 2000 amp fused switch. The second thing would be to determine how long those loads can be down while connecting the temporary power source. The last thing would be for the engineer to determine the exact points of connection for the temporary power source. If that switchgear is all bus bar a point of connection for the temporary source may be difficult to find without bus modifications.
I would expect that the temporary power source is going to have to be a generator.
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Thanks. So obviously the fused switches in the board is not indicative of actual load?
If it is a generator we will still have to connect somewhere on the bus and possibly modify the bus.
 
Alwayslearningelec said:
Thanks. So obviously the fused switches in the board is not indicative of actual load?
If it is a generator we will still have to connect somewhere on the bus and possibly modify the bus.
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No, the main breaker is not an indication of the actual load. Sometimes older switchgear of that type will have a watt hour meter with a demand needle and that would be the best way to know the real load. If that does not exist and the installation of the new beaker is not right away, a power meter could be connected to show the actual load over a period of time, but, in my opinion, it is the engineer's job to tell you the load and how to make the temporary connection to the bus.
 
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