Step-up Transformer

Status
Not open for further replies.
T

Talmadge

Member
I don't really know where to post this question, so I'm posting it here in the General Electric Forum. If I'm posting in the wrong place, I'm sure the moderator will place this thread in the correct place and correct me.

Here is the question...

Is it possible to get 480 volts at 600 amps form a 120/208 200 amp service by using some sort of transformer?

I have a client that wants to install three, 3 phase, 480 volt, 120 KW Car bottom furnaces in a warehouse suite in a multi suite building and the existing service for the suite is only 120/208 at 200 amps, the building has a 2000 amp service gutter that all of the suites meters tap out of. The client has other equipment and I will also need to utilize 208 for the existing HVAC and low voltage (120 volt) receptacles and lighting. Total connected load for the lighting, HVAC and water heater is 38.7 amps.

We have petitioned the power company for permission to add a 600 amp, 480 volt service to service this one suite, we are awaiting a decision for their engineers. I may need an alternative solution if the request is denied. The only solution I have is it upgrade the 200 amp service at 208 to a 600 amp sevice and increase the voltage with a regular transformer, but the power company may deny that also if it overdrives the 2000 amp main service transformers (on the pole).

I'm just at a loss on alternatives and need some input and I felt this would be a good place to start.

-Talmadge
 
Talmadge said:
Is it possible to get 480 volts at 600 amps form a 120/208 200 amp service by using some sort of transformer?
Click to expand...


Short answer no. Since your voltage is stepping up the current on the primary would also step up at the same ratio. If I did the math correctly, for a 600 amps of output at 480 volts you would need about 1440 amps at 208 volts.
 
No, there's no way to pull 500kVA (or 360 kW) out of a 75 kVA service.
A service gutter than can handle 2000 amps isn't necessarily supplied with utilization transformers that can supply 2000 amps.

Work with the power company engineers on this one. If you're going to consume (more to the point: pay for it) the power, I'd be very surprised if they aren't willing to provide it. (more to the point: bill you for it)

I also wonder if this warehouse building is adequately fireproof for this application.
 
I agree with the others. Look at the math: 480 volts times 600 amps times the square root of 3 equates to about 500 KVA. Then divide that by 208 volts and divide again by the square root of 3 gives you about 1400 amps. It's a new service or forget it.
 
drcampbell said:
No, there's no way to pull 500kVA (or 360 kW) out of a 75 kVA service.
A service gutter than can handle 2000 amps isn't necessarily supplied with utilization transformers that can supply 2000 amps.

Work with the power company engineers on this one. If you're going to consume (more to the point: pay for it) the power, I'd be very surprised if they aren't willing to provide it. (more to the point: bill you for it)

I also wonder if this warehouse building is adequately fireproof for this application.
Click to expand...

Good Point - I have already informed my client (the property owner) that he will have to upgrade the demising wall to a two hour burn rating in order to get the dispensation if the power company approves. He wasn't happy, he said it would be expensive. I told him if you think that is expensive, wait until you see how much the power company is going to charge you for the upgrade.
 
IF the power company agrees to supply the new service there are Code compliant methods that would not require work on the demising wall. Once the power company agrees, you can discuss the details with an electrical contractor or inspection authority.
(For that size load the power co. may well be cooperative)
 
Talmadge said:
Here is the question...

Is it possible to get 480 volts at 600 amps form a 120/208 200 amp service by using some sort of transformer?
Click to expand...
Not even almost. Current varies inversely with voltage.

600a at 480v would require 1200a at 240v. You have even less voltage plus losses to deal with.
 
Status
Not open for further replies.
Top