USA supply in UK?

[justin_t]

Hi

Has anyone heard of a device that allows 240 VAC 50 Hz in the UK to be transformed to 110 VAC 60 Hz.

I need it to test a PCB that draws 10A max.

I can find plenty of transformers that will supply the voltage level but not the frequency.

Im considering using an inverter to supply the 240 VAC 60 Hz and transform it down to 110 VAC 60Hz...

Thanks


Justin

 

[Nigel Goodwin]

Why do you need the frequency?, most items are fine at 50Hz or 60Hz.

 

[justin_t]

I know what youre saying but i dont want to test the unit here and then when i try it in the USA, we have some problem that is due to the 60 Hz supply. Maybe im just being too thourgh but i want to eliminate all possible faults.

 

[Nigel Goodwin]

Only an incredibly small number of devices would be affected at all by moving from 50Hz to 60Hz - and it should be obvious if your boards would be affected.

If you want to do it via an inverter, you MUST make sure it's a 100% sinewave output (VERY expensive), or you're not testing anything like reality. It may be easier (and more realistic) to buy a 110V 60Hz generator, which will probably be better for you?.

But, depending on the device, it's probably pretty pointless?.

 

[justin_t]

Ive decided just to test the unit using 110 VAC at 50 Hz using pretty much a tansformer that the builders use in the site. Fingers crossed it shouldnt cause me any problems. Ill let you know how i get on...

 

[Henry T]

How's is the power supply built? Is it a standard rectifier and buffering? If that's the case, I believe you shouldn't have any problems...

 

[justin_t]

The PCB works fine on the 110 VAC 50 Hz. I just hope now that there will be no problems when used on a USA 60 Hz frequency but as you say, all the components that are exposed to AC are rated for both 50 and 60.

I have a further question about the USA mains supply.
Is it correct that houses/industry have both 120 VAC (1 phase to neutral) and 240 VAC (phase to phase) as standard?

Which is most common or is both options available in all/most buildings in the USA?

 

[Edwin2]

Why not use an inverter that supplies 110V/60 Hz, and power that from a (car)battery ?

 

[Nigel Goodwin]

The PCB works fine on the 110 VAC 50 Hz. I just hope now that there will be no problems when used on a USA 60 Hz frequency but as you say, all the components that are exposed to AC are rated for both 50 and 60.

I have a further question about the USA mains supply.
Is it correct that houses/industry have both 120 VAC (1 phase to neutral) and 240 VAC (phase to phase) as standard?

Which is most common or is both options available in all/most buildings in the USA?

As far as I'm aware, both are common - 110V can't provide enough power, so 220V is used for high current appliances, water heaters, tumble dryers etc. Normal low power devices, TV's, stereo's etc, run off 110V.

 

[saturn1bguy]

I have a further question about the USA mains supply.
Is it correct that houses/industry have both 120 VAC (1 phase to neutral) and 240 VAC (phase to phase) as standard? Which is most common or is both options available in all/most buildings in the USA?

Residential is split-phase, i.e. a single-phase 240VAC center-tapped transformer, three wires to the dwelling. That's 120VAC between either leg and neutral, or 240VAC across both legs for high-power appliances as Nigel points out.

Many industrial buildings have 3-phase 208VAC. That's 208V between phases and 120VAC between any phase and neutral. Sites that require more power use higher 3-phase voltages.

 

[Leftyretro]

This post reminds me of a problem I came across in the 70s when I was a field engineer for a minicomputer company. I was tasked for a service call to a large OEM company here in the US that was building a large system that was going to be shipped to one of their customers in Japan.

The minicomputer system would power up and much of it appeared to function fine but they couldn't seem to write files successfully to the hard disk drive. Long story short, after much troubleshooting, was that the drive was properly ordered for 50hz power that the end customer used, but testing it in the US with 60hz power caused the sector timing to be off enough to not be able to function. The rest of the components in the computer system didn't mind 60hz Vs 50 Hz but the synchronous drive motor in the disk drive was not spinning at the correct speed. Yes hard drives in the 70s used AC motors for spinning the disk. That was one problem I had not come across or even heard about and not knowing at first that the unit was ordered for 50hz had me scratching my head for a while. Only with using a O-scope to check disk timing did the problem slowly become apparent. Took most of the day to figure out. Sometimes the hardest faults to solve are the ones that aren't really faults but rather a design conflicts.

PS: I later read that at the time or maybe still, that Japan uses both 50hz and 60hz in different parts of their country. Not sure that was or is still true, but that must have complicated things for them at times

Lefty

 

[justin_t]

progress update:
i have now powered up the unit from a 115 VAC transformer at 50Hz. Everything seems to be working fine. I have checked all the components again and they are rated for either 50 or 60 Hz. Im pretty sure we are covered for operation in the states.

I dont think ill run into any problems in my micro processor as it is DC supplied, the transformer and rectifier are rated to 60 Hz and there is a voltage regulator after the rectifier/smoothing capacitors. Will keep you updated on my progress.

Justin

 

[justin_t]

would the frequency that a 50 V smoothing capacitor be of importance?
It states in the data sheet that the capacitance tolerance is 120 Hz at 20 degrees celcius. I presume the 120 Hz is the twice the 60 Hz mains frequency after rectification. Will this derate as the temperature in the enclosure rises?
Ive attached the data sheet for the capacitor ive been using.

 

[Nigel Goodwin]

would the frequency that a 50 V smoothing capacitor be of importance?

Not with such a tiny change - you're really thinking FAR too much about a very trivial difference.

 

[justin_t]

i know i know but i just dont want any problems to creep up later on when im demonstrating the operation of the unit using the US supply.

 

[Nigel Goodwin]

i know i know but i just dont want any problems to creep up later on when im demonstrating the operation of the unit using the US supply.

Is the device secret in some way?, many posters here could tell from the curcuit if it might have a problem, if you could post the circuit.