Digital phase converters and DC brakes

[Guineafowl]

Digital Phase Converter 4Kw/5.5Hp 240V in 400V Out - JFK Electrical

4 Kw / 5.5 Hp 240 Volt Digital Phase Converter Input Volts 240 Single Phase ( Supply 32Amp type C Mcb ) Output Volts 415 Volt 3 Phase ( No Neutral ) Dimensions L 280mm x W 145mm x d 180mm Weight 4.5 Kg Change your Garage/Workshop from single 240 volt to 3 phase 415 … Continue reading Digital...

www.jfkelectricalni.com

Looking for 3 ph in the workshop, and this ^^ comes recommended. Looked at rotaries, but they seem noisy and expensive.

Current machines to run:
1. 1.5kW planer, normal DOL start.
2. 2.2kW radial arm saw, DOL start and DC brake.
3. 2.2 and 3kW spindle moulder (+small power feed) DOL start, but two-speed Dahlander motor.

The JFK electrical chap rang me to ask what is to be powered, and says the DPC won’t run a DC brake without a (very expensive) sine wave filter, but I can’t see why not. Any ideas?

I already have some VFDs, but I’ve ruled them out for these machines because:
1. It’s one per machine and I’ll probably get more 3ph stuff in the future.
2. They don’t like DC brakes, and braking resistors are pricey.
3. Hard to set up for a Dahlander motor.

 

[m_c]

You'll probably need to go bigger to handle those motors.

DC braking can cause quite a lot of noise, which the sine wave filter will handle and avoid any transients getting back to the VFD. Sine wave filters aren't that expensive.

I'm running a standard boost/step up VFD, with Sine wave filter, but I kept the idler motor from my old rotary setup just to provide a bit extra damping in the system, since it primarily powers a CNC lathe.

 

[Guineafowl]

You'll probably need to go bigger to handle those motors.

DC braking can cause quite a lot of noise, which the sine wave filter will handle and avoid any transients getting back to the VFD. Sine wave filters aren't that expensive.

I'm running a standard boost/step up VFD, with Sine wave filter, but I kept the idler motor from my old rotary setup just to provide a bit extra damping in the system, since it primarily powers a CNC lathe.

I was thinking of an idler motor - just pick up a smallish one second hand.

To be clear, this is a DPC, which I think is distinct from a VFD. It can power multiple motors, and be switched on with no load.

What about a surge protector after the DPC?

Where do you get your sine wave filters? All I can find is massive £400 ones.

 

[Agroshield]

To be clear, this is a DPC, which I think is distinct from a VFD.

What about a surge protector after the DPC?

When you use the keyboard to write the names of the two items, you are correct that they are distinct. One needs V, F and D keys; the other D, P and C keys. My point is that just because different names are used for marketing purposes does not mean there is any significant differences in the electronics inside. To make that distinction stick, you need rather more robust sources than the description on a sales page.

A surge protector stops a surge from the mains going into the machine. Any DC braking input will be trying to go from the motor towards the VFD.

A Serge protector stops a French singer damaging the machine.

 

[Guineafowl]

AFAIK…

they both produce a PWM 3ph waveform from a DC bus, derived from the mains.

A VFD tends to be hard-wired and configured to one motor. A DPC can power up 3ph sockets and pretty much be used like real 3ph.

I meant a surge protector between DPC and sockets. They should work bidirectionally. Could be wrong.

 

[m_c]

That DPC is a VFD, it's likely just not programmed for the variable bit (well it will be, but ramp time will likely be minimal).
And a quick google would put it as a Winston WSTG600 - https://www.cnwinston.com/4KW-Inver...uency-Inverter-WSTG600-2S4-0GB-pd6529334.html
However nobody seems to sell that brand out with the B2B sites.

My setup uses the 7.5Kw version of this - https://www.aliexpress.com/item/4000850318377.html
Combined with this sine filter - https://www.motorcontrolwarehouse.co.uk/ncnw-933-6-sine-filter.html (although they were only £120 + VAT when I bought it a few years ago!)
It would start my old Harrison Mill (2hp/1.5kw motor) in top gear without any issues, and that always took a couple seconds to wind up to top speed.

It now mostly powers my CNC lathe, which has a 5.5KW spindle, and dims the lights when winding up to full speed.

 

[Guineafowl]

Thanks for the advice.

Just by chance, a 12kW Boost Energy rotary, a few miles down the road, just popped up on ebay for £700. I’ll take a punt on that.

Should be big enough, and handle the DC brake and Dahlander switching, hopefully.