380V..480V input, 220V output

[Rob#]

Using 24Vdc power supplies with input ranges 380V..480V are very common. I wonder if anyone knows if there is anything similar to convert 380Vac..480Vac to single phase 220Vac/230Vac.

There are lots of VFDs that go the other way round and convert single phase to three phases and I know that there are lots of transformers that allow different configurations. My question is if anyone knows a power electronic device that controls the output so that I get 220V no matter what the input is. (as long as it's between 380V and 480V) I've spent quite some time searching the internet but couldn't find anything.

 

[Jraef]

No, because that can be done much much simpler with a transformer. How much power do you need? There are lots of small Control power Transformers with multi-tap primaries that can accomplish this, so you would just have a selector switch to select 380 or 480 as the input. CPTs like this are typically available up to 1kVA, maybe higher (I’m not looking anything up for you).

 

[Rob#]

Thanks for the response. The customer's idea was to use a 1ph VFD rather than a transformer, because this panel goes to other countries and he wants to avoid settings depending on where the panel is installed. I think the selector switch would be a good idea. I'll try to convince the customer. I only need 100W.

 

[petersonra]

I would not be using a selector switch.

Just making an option on your drawing for whatever voltage is supplied is a better choice in my mind. Otherwise some fool will change The switch position. It's more work to rewire something so fools are less likely to do it.

 

[Rob#]

Well, that was exactly the reason why I started this thread: the customer doesn't like look-up tables in the drawings with different wiring options. Because I will use the 220V for a 1ph/60Hz motor the idea was to use a 1ph/1ph VFD. (or a 3ph/1ph)

 

[zbang]

The customer is going to spend a lot of money on not having those look-up tables and changing taps.

I only need 100W.

Can you use a DC motor instead?

 

[Rob#]

Using a DC motor would be the preferred option. The problem is that this is for an upgrade of an old machine type, I want to avoid changing the flange, shaft etc. The 220V motor is in a box along with the capacitor, the gear and two limit switches. We buy the box with all that as one part. I reached out to the supplier, they want 5 figures to "develop" a new solution with a 24Vdc motor. I am considering buying the whole thing and replace the motor myself. (RSM 884/3)

 

[Jraef]

Well, that was exactly the reason why I started this thread: the customer doesn't like look-up tables in the drawings with different wiring options. Because I will use the 220V for a 1ph/60Hz motor the idea was to use a 1ph/1ph VFD. (or a 3ph/1ph)

The problem here is that most single phase motor types are incompatible with a VFD. The only type of single phase motors that can be run on VFDs are Permanent Split Capacitor (PSC) type and Shaded Pole type, both of which are used primarily on variable torque type applications (pumps and fans) because they don't provide a lot of starting torque.

I used to build control panels for a company that made high pressure portable steam cleaners, they had the same issue; shipping them all over the world, no control of what voltage it was going to be. So they set everything up for 200V (Japan) as the worst case scenario, then I had a custom cam switch on the front controlling the transformer primary taps: 600V, 480, 400, 240, 208 or 200V (straight through, no transformer). Nobody ever complained.

 

[synchro]

If you need to operate at 380V then it's very likely that it would be at 50 Hz. The motor nameplate posted shows that a 2.2uF capacitor is needed at 50 Hz, and 1.8 uF at 60 Hz. So if you need to accommodate two different capacitances, then it would not be much more effort to implement two selectable transformer taps. You could have both a 1.8uF and a 0.4uF that can be connected in parallel to get 2.2uF if you want all of the boxes to have the same components.