Domestic single phase to 3 phase advice please

[SUNRAY]

Schneider model number = ATV12H075M2 0.75KW. Here is the same unit on the RS website https://uk.rs-online.com/web/p/inverter-drives/6695783/ . I'll get back to you on the control box data plate.

This is a single phase in to 3 phase out variable speed drive. Despite what Simon says, Variable Speed Drives are sinewave, they are designed to smoothly control motors from zero speed to maximum and this will only work with a sinewave.

You say this is not connected at the moment, I'll make a massive guess that it was fitted to this machine for one of its previous lives to run it on single phase and possibly it only requires reconnecting.

Please see page 52 https://www.efka.net/fileadmin/down...82FA2315/EN_BAPL_6F82FA2315_1(1)_300301_A.pdf for an idea of where the cables go.

I'm thinking more about motor power which I'm guessing comes directly from the contactor (green and red buttons) and mains power to the control box.

I think that's how this one works. As soon as I switch the power on I can hear the motor running. It's surprisingly quiet.

Hope this helps a bit.

That is very normal and it does need to be quiet, imagine twenty of them running in the same room.

 

[Simon35]

This is a single phase in to 3 phase out variable speed drive. Despite what Simon says, Variable Speed Drives are sinewave, they are designed to smoothly control motors from zero speed to maximum and this will only work with a sinewave.

You say this is not connected at the moment, I'll make a massive guess that it was fitted to this machine for one of its previous lives to run it on single phase and possibly it only requires reconnecting.I'm thinking more about motor power which I'm guessing comes directly from the contactor (green and red buttons) and mains power to the control box.
That is very normal and it does need to be quiet, imagine twenty of them running in the same room.

Wrong.

VSD outputs are not pure sine wave outputs.

They use pulse width modulation, with outputs firing in the kHz range.

Which is why you get very high voltage rates of change and consequently high stresses across insulation.

I'm guessing you don't do much drives work.

 

[bernardgreen]

imagine twenty of them running in the same room.

I recall albeit vaguely the image of about 100 machines in the sewing room of a London garment manufacturer.

 

[bernardgreen]

double post

 

[SUNRAY]

Wrong.

VSD outputs are not pure sine wave outputs.

They use pulse width modulation, with outputs firing in the kHz range.

Which is why you get very high voltage rates of change and consequently high stresses across insulation.

I'm guessing you don't do much drives work.

My apologies, yes I have done loads of work with VFD's in the 15 years I've been in the controls industry but mostly wiring them up and returning for alterations/faults after commissioning or later. As such I've not needed to get too involved with the 'workings' of them except on one job where one of a pair of 55KW pumps kept 'tripping' the inverter which I think, but can't be sure, was a Telemeq. Before I was asked to have a look, several others had offered solutions including swapping the pumps over onto the opposite VFDs and changing the faulty VFD to ABB. As part of my tests I compared the voltage and current on the supply side and at the motor between the 2 pumps using DMM/clamps and finding no difference I also used an oscilloscope.

Having worked on a selection of DC drives where PWM is commonplace I was rather surprised to see the above pumps showed no sign of PWM, measured earth to phase directly with the scope and via an isolating transformer phase to phase. I did notice that as a pump started from zero and ran at a very slow speed the drive voltage was somewhat higher than than at higher speeds by maybe 10% and the rising edge was steeper.
Rather foolishly, it seems, I assumed that all VFDs work in the same way.

BTW the fault turned out to be an a changover valve not being controlled properly.

 

[crystal ball]

I recall albeit vaguely the image of about 100 machines in the sewing room of a London garment manufacturer.

Some of the bigger Clarks factories had several hundred in one room, the noise came from the needle mechanisms and the operators gossiping, all gone now

 

[SimonH2]

Isn't this a case that calls for a simple capacitor conversion ? It starts under no load, and runs continuously.
Without an extra start cap it'll be poor at starting, but without mechanical load this might not be too bad.
That's basically all a Transwave static converter is - though they normally have a step-up auto-transformer to generate 415V for 2 of the 3 phases. They also have a voltage monitor that cuts in additional caps when it detects a low voltage on the 3rd phase during starting of a connected load.

 

[BotleyBouy]

Is there an "Idiot's How-to" guide to show how to do this?

I found something on Youtube yesterday which seemed to indicate that single phase went to the control box while 3-phase went to the motor. Typically I can't find it again at the moment but I'll keep looking.

 

[SimonH2]

For other than a simple motor, it needs some knowledge of the system. For example, whether the controls need 415V from across 2 phases, or 240V from 1 phase and neutral. In the former, a static converter is simple to use but you need to know which two phases need to be the "real" supply and not the synthetic third phase with is unstable in voltage. For the latter, then you need the control run from upstream of the converter, and it's a little more wiring.

 

[BotleyBouy]

This is the one I was hoping for
View attachment 177115
There are many format variations on industrial sewing machines (and other machines for that matter) and some used a 3ph motor with a single phase VFD.

Apologies for the delay. Here is the data plate on the speed controller...

 

[SUNRAY]

Does the power cable for the motor come from the speed controller box or direct from the starter (red and green buttons). I'm guessing the latter with a piece of grey YY cable.

 

[BotleyBouy]

The motor is off the machine now but both are at the workshop so I'll take some more photos when I'm back in there. From memory though, the cable from the on/off switch goes into the back of the box under the motor.
Could it be that the motor is driven by 3-phase but the speed controller is running on 240V single? Is the speed controlled by an electrically operated clutch? I'm going to have to strip it down to find out. I'll post up photos when it's all apart.

 

[SUNRAY]

What I'm accustomed to is the speed controller and motor being bolted together as one unit. The power goes from the starter to the speed controller (as you describe) and from there to the motor internally, so it may not be visible.

The clutch unit (being the unit which is more likely to be removed for repair) has an easier method of disconnection, in this case a plug.

The box will most likely be running on a single phase but it's just as likely all 3 phases are routed there for the motor.

 

[BotleyBouy]

Here's a photo showing a black cable coming from the control box to the clutch area of the motor. There was a thicker grey cable from the on/off box to the back of the motor/box but I haven't got a photo showing whether that goes into the rear of the box or the rear of the motor. My memory tells me it goes into the connection box on the motor.

Can you see the grey cylinder with the bellows (top left in the photo)? This is connected electrically to another control box (not the one in the photo) which is in turn connected to the box you can see in this photo. It looks like a solenoid powered ram. Have you any idea what it's for? There is an identical unit mounted horizontally underneath the table to the front of the sewing machine but that's not connected to anything mechanically either.

 

[Simon35]

Here's a photo showing a black cable coming from the control box to the clutch area of the motor. There was a thicker grey cable from the on/off box to the back of the motor/box but I haven't got a photo showing whether that goes into the rear of the box or the rear of the motor. My memory tells me it goes into the connection box on the motor.
View attachment 177992

Can you see the grey cylinder with the bellows (top left in the photo)? This is connected electrically to another control box (not the one in the photo) which is in turn connected to the box you can see in this photo. It looks like a solenoid powered ram. Have you any idea what it's for? There is an identical unit mounted horizontally underneath the table to the front of the sewing machine but that's not connected to anything mechanically either.

Looks like the rod coming out of the unit is threaded, so maybe a motor driven screwjack (powerjack) for adjusting table height? Dont know if that adjustment is a thing on sewing machines?

That cable up the centre of the photo is damaged.