Moving switchgear

[thomasjones]

Firstly, I am not an EE or an electrician. I am the engineer (chemical) of an old industrial plant in NJ.

Our electrical switchgear is in a flood prone area and I am tasked to install new switchgear in a nearby higher elevation location.

The main power is a 2000A, 240V 3 phase, 3 wire delta-delta configuration. We bring power in at 4160V to three single phase distribution transformers on a pad.

The secondaries are wired to a three phase bus and then to 5 conduits containing 3 cables each. These cables are run through a wall and are then wired to the three phase bus in the electrical utilities’ cabinet; 5 cables per bus-bar.

Can anyone tell me why the wiring is configured this way? It seems like a lot of conductor material.

The 240V is used primarily to drive induction motors on agitators, vacuum pumps etc. The facility originally ran large resistive heating elements for their stills but thermal oil is used now. (The load on the 240 system does not rise above 800A.)


I am hiring an industrial electrical contractor to do the change but I would like to know something about the way things should be done prior to contracting.

Thanks
Tom

 

[augie47]

Sight unseen, it sounds like a pretty common installation especially for an older industrial facility.
The older ungrounded systems are fairly rare today.
The 3 conductors per conduit is SOP as the Code requires each phase to be in a conduit and the 5 runs were probably selected to provide the 2000 amps to meet the gear size and using multiple conductors as they are easy to handle

 

[Ingenieur]

Sight unseen, it sounds like a pretty common installation especially for an older industrial facility.
The older ungrounded systems are fairly rare today.
The 3 conductors per conduit is SOP as the Code requires each phase to be in a conduit and the 5 runs were probably selected to provide the 2000 amps to meet the gear size and using multiple conductors as they are easy to handle

sums it up perfectly

if you are buying new gear (rather than relocating the existing) and are confident of the 800 A and the electric heating is not coming back you may consider downsizing to 1000 or 1200

 

[Ragin Cajun]

You are looking at a major effort. It must be done right or your facility may be subject to lengthy downtime.

Suggest you involve an experienced engineer and get stamped drawings.


rc

 

[Fulthrotl]

You are looking at a major effort. It must be done right or your facility may be subject to lengthy downtime.

Suggest you involve an experienced engineer and get stamped drawings.


rc

further suggest you get smart sparky for design build, who brings his
own EE for the approved drawings.

 

[electrofelon]

You are looking at a major effort. It must be done right or your facility may be subject to lengthy downtime.

Suggest you involve an experienced engineer and get stamped drawings.


rc

I dont really see an electrical engineer's involvement necessarily being required, I would be more concerned with getting a good electrician. I do agree with the downtime concern, you might want to see what a few different people can do you for. I swapped out a 2000 switchboard for a 800 amp and 250 amp panelboard last year and the only downtime was two four hour periods at night. I also agree with Iggy, that if you are really down around 800 - 1200 amps, you can stay in panelbaord territory with will cut costs quite a bit.

 

[Ingenieur]

Engineer or electrician is a toss-up
the key is pre-work
locate new sg between old and loads to intercept
Or use the old as a termination cabinet and have new conduit/conductor pre-installed to new sg
have the new service conduit/conductors ready to go

a scheduled shutdown is onviously prefered
if something can go awry it will, mr murphy

without seeing plans it's all WAG lol

get 3 quotes/proposals
with their plan and estimated downtime
one plus for using an engineer is you have plans/specs/contract to bid/solicit with
in my experience you can offset the enginers fee with the lower competetive pricing
and you can still allow the bidder to propose value engineering/alternatives since it's private $$

often a contractor can get the equip cheaper than the end user
so have him supply it
plus if it's not right he owns it
it's worth his mark up

I do side work for contractors who will have me walk the job with them and come up with a plan or just provide a sanity check

 

[Jraef]

If any of your loads run on VFDs now, delta is no longer a great idea. When most industrials used it to aid in reliability if the plant and process, power electronics were still a ways off. If that's the case, this might be the time to start rethinking strategies.