America 208 volts ? 1

[DTSFA]

hi

we have a 230v 50hz load, around 5A load. Single phase motor / pump (some electronics, controls, 24 v dc. too )

our device needs to go to show in america where i am told the supply is 208 v 60 hz

is there a UK device/solution/converter, or , transformer supplier, that you can recommend to give us 230v ?

thanks

 

[DTSFA]

just a thought, is the 208v in america the line to line voltage , between two phases?

and the single phase supply 120 v ?

thanks

 

[itsmoked]

Yes and Yes.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[itsmoked]

Oh! And Yes.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[cranky108]

Some services are 230 V line to line, and some are 208 V line to line, depending on where you live.

 

[dpc]

If you have an induction motor, the voltage is not your only problem. 60 Hz vs 50 Hz is an issue as well.

If this is for a specific trade show, check to see if 240 V or 208 V is available. But it will be 60 Hz. You can always bring your own generator along.

 

[BrianE22]

A "Buck/Boost" transformer is often used to boost from 208 to 230 VAC.

 

[cranky108]

If the motor is for 50 Hz, you probally want a little bit lower voltage, to reduce the speed, so a Buck/Boost transformer is a good idea to get closer to 240, but a little lower than 240.

 

[jraef]

230V 50Hz = 4.6V/Hz, that is what your motor is designed for. To keep it from burning up at the trade show (really bad idea), you need to keep that V/Hz ratio within +-10%, and as close to +-5% as you can get. So first CONFIRM that the voltage at your specific trade show facility is 208V 3 phase, but I will say that 208V 3 phase 4 wire is the usual power distribution at large trade shows here. If it is, then you will need for the voltage to be closer to 276V (60 x 4.6), but no less than 250V. That's going to be a little tricky, it will require that "buck-boost" transformer arrangement that cranky108 mentioned, but to BOOST, not buck, the voltage.

But there are other issues.
[ol 1]
[li]If internally, your control system is expecting 230V line to grounded neutral, you may have trouble with the fact that our 208V is going to be line to line, and line to neutral is 120V. So you need someone to investigate ALL aspects of your electrical panel to ensure that it will work correctly when it gets here.[/li]
[li]You did not say what KIND of pump it is. When you go from 50Hz to 60Hz on a centrifugal pump, the flow, and thereby the LOAD on that pump motor, will increase at the cube of the speed change. So in this case your pump will run at 120% speed, therefore your flow will increase to 1.2³, or 173% of what it was at 50Hz and since flow = load, your motor will be overloaded (unless it was grossly under loaded before). If you have a manual flow control device somewhere, you have to make sure that you throttle the flow back to the same rate it was designed for, or you will overload the pump motor. If you don't have that device, you will have to install one. [/li]
[/ol]

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[VEBill]

It'd probably be better, faster, cheaper to simply rent a suitable 230v 50Hz output power source that can supply the required 5A (and, obviously, powered by US standard line voltage at 60Hz). We have similar systems to supply 400Hz aircraft power in our labs, and they're in this kilowatt power range, if not more. They're a big heavy (2-man lift) 19-inch rack.

You should bring a wired power socket to be connected to the power source output terminals.

This approach skips all the other complications. All approaches have risk of single point failures. In this case, you should probably rent two; primary and a spare.

I'll try to find a brand name...

 

[VEBill]

Here's an example of the sort of thing that might meet you requirements.

http://www.behlman.com/powpasce.htm

My search terms were: 50Hz power source

Another approach would be to track down a Test Equipment Rental house and ask them what they have avaiable. Don't cut the current too close. If you actually need 5A, get one that can provide 7 to 10A (risk reduction, pump startup, cautious approach).

 

[VEBill]

Another brand that I've seen before:

http://www.elgar.com/products/index.htm

 

[ScottyUK]

Another vendor, nice products too.

 

[jraef]

Just be careful, some of those electronic power supplies cannot handle starting an induction motor, especially a Cap Start one.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[waross]

Another approach may be to change out the pump motor for a three phase motor and drive it with a VFD.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

Probably the least complicated approach actually.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[DTSFA]

hi all

thanks for all replies,

we are going to make our own 120/230v transformer box with suitable MCBs to account fro start up current.

Fully take on board the v/hz issue.



VE1BLL, thanks have book marked that device/supplier

other ideas great, unfortunately we dont have the time to swap out motor for 3 phase one,
we do have some comfort , that the USA vendor has apparently connect our kit to their supply, and feedback is, all ran ok.

But, I dont know how long the lift was run for at their premises

 

[rmw]

If they aren't running it at a Trade Show, it probably will never fail. But take it to the show......



rmw

 

[jraef]

Smoke coming from the equipment at a trade show... really really bad.

Trust me, I know

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376