Dsg wont go

Mr muddle · Apr 5, 2020

Can anyone help, this is causing me deep distress!
I have DSG 1330 toolroom lathe, 7.5 hp motor, I have no 3 phase but have aquired a 7.5kw rotary inverter which I did not use due to later reading that it would not be suitable to run the lathe. I then bought a jaguar 11kw digital inverter as advised only to find that wouldn't do the job either as it's designed to run a motor only not to pull contactors in and run motor. It doesn't run motor alone either.
Can anyone suggest any options to get me out of this ever increasing money pit of useless electrical equipment I seem to be collecting?
As I bought the rotary inverter dismantled I would also like any info on re commecting cables in correct order.

SomeoneSomewhere · Apr 5, 2020

Could you post more details about exactly what you have?

Do you mean a 'rotary converter'?

atomarc · Apr 5, 2020

Mr. Muddle,

Welcome to the forum.

I'm not familiar with that brand of inverter but did a quick search on Google and found a few hits that indicated that it is more or less, a standard VFD, and if sized properly should run your machine.

Typically, no VFD (inverter) will operate contactors etc, as that's not their main purpose. This still doesn't mean that drive, if of proper size, won't power your lathe splendidly.

Before I tossed in the towel I would grab the book that came with the drive and read it, front to back..a couple of times. After that, come back with questions and a clearer understanding of what a VFD will do, and how it does it.

Stuart

EmGo · Apr 5, 2020

Mr muddle said:
Can anyone help, this is causing me deep distress!
I have DSG 1330 toolroom lathe, 7.5 hp motor, I have no 3 phase but have aquired a 7.5kw rotary inverter which I did not use due to later reading that it would not be suitable to run the lathe. I then bought a jaguar 11kw digital inverter as advised only to find that wouldn't do the job either as it's designed to run a motor only not to pull contactors in and run motor. It doesn't run motor alone either.

DSG means Dean, Smith, Grace ? Nice machines.

I have no idea why you think a rotary converter "won't work" ? They work fine.

What is this "won't pull in the contactors" ? If you run the three-phase to the incoming connections just like it was set up originally, why won't it "pull in the contactors" ? I know people don't usually do it that way, but see no reason it wouldn't work. Unbalanced loads would not be ideal ? But it still should function.

rons · Apr 5, 2020

Mr muddle said:
I did not use due to later reading that it would not be suitable to run the lathe.

I then bought a jaguar 11kw digital inverter as advised only to find that wouldn't do the job either

What are you reading & who is advising you?

Mr muddle · Apr 6, 2020

Thanks for replies and interest in my problem, as you said it is a VFD which should run motor ok being 11kw and a 7.5 hp motor?? it tries to turn motor but keeps tripping out, and with contactors connected on lathe it brings them in and then trips out and motor doesn't move at all, should I be looking for an even bigger VFD?(trip setting on vfd is at max).
As for the rotary inverter it's a Sturdy make unit which I bought from an ice cream making company and it was running a 2x 5hp motors so was hoping it would run lathe?? Unfortumately I have no idea how to connect the unit back up so any info on this would be appreciated. Could upload pics if needed?
Thanks again.

SomeoneSomewhere · Apr 6, 2020

EmanuelGoldstein said:
DSG means Dean, Smith, Grace ? Nice machines.

I have no idea why you think a rotary converter "won't work" ? They work fine.

What is this "won't pull in the contactors" ? If you run the three-phase to the incoming connections just like it was set up originally, why won't it "pull in the contactors" ? I know people don't usually do it that way, but see no reason it wouldn't work. Unbalanced loads would not be ideal ? But it still should function.

The contactors won't pull in until the VFD ramps up to somewhere around 1/2 voltage. At that point, the sudden inrush from the direct-on-line motor is likely to trip the VFD.

It would be possible if a significantly oversized VFD was used that could supply DOL starting current and had the trip parameters adjusted, but at that point you have a Phase Perfect unit.

Wire the motor direct to the drive, bypassing the contactors. Wire the switches that used to switch the contactors to the digital inputs on the drive. These need to be volt-free contacts; connecting 240V into the digital inputs will make things go bang.

Peter from Holland · Apr 6, 2020

What is your powersource
240Volts single phase ???
What fuses does it have
Do the fuses trip or the VFD?
What voltage is the motor ??
Dual voltage single speed or dual speed single voltage ??

Peter

EmGo · Apr 6, 2020

SomeoneSomewhere said:
The contactors won't pull in until the VFD ramps up to somewhere around 1/2 voltage. At that point, the sudden inrush from the direct-on-line motor is likely to trip the VFD.

Ah. So they are basically way undersized. The only one I ever had was on a 15 hp motor and it made full percherons right out of the gate.

It also blew up all the time but oh well, can't have everything

SomeoneSomewhere · Apr 6, 2020

VFDs can make tonnes of torque out of the gate even just sized 1:1. But they do it at ~5Hz and 30V. If you make it so the VFD can't output less than ~100V to the motor, you'll have a bad time.

EmGo · Apr 6, 2020

SomeoneSomewhere said:
VFDs can make tonnes of torque out of the gate even just sized 1:1. But they do it at ~5Hz and 30V. If you make it so the VFD can't output less than ~100V to the motor, you'll have a bad time.

You're right, I wasn't thinking of them ramping up, just making 60hz electric right away.

What happens if you just tell the thing to start out at 60 hz ? I don't see any point to the vfd thing as a retrofit, older machines all have gearboxes or different pulley ratios. Once in a while infinitely variable speed would be nice but for real machining, it's not that big a deal.

I like the rotary, myself. Simple, works, no stinking electronics to break. Electronics always break.

Mr muddle · Apr 6, 2020

Hi, the VFD is powered from consumer unit with 10mm cable and 40a trip, it's the VFD that trips not the fuse.
The lathe motor is a single speed 3 phase.
I've wired the VFD direct to motor to bypass contactors, motor turns maybe 1 revolution and then the VFD trips, although last week the motor did run up?
I dont think the motor is at fault.
Does anyone think the rotary inverter would work if I could work out how to rewire, I've been told not to bother as it doesn't supply perfect 3 phase and I would end up with tooling Mark's in my work due to fluctuations in speed caused by phase variations????

atomarc · Apr 6, 2020

Attempting to help is quite frustrating as you are not sharing some important information that will allow sensible answers to be given. Although you haven't indicated your supply voltage, 11 KW is equal to about 14.75 HP which under the usual rule of VFD's on single phase (240) should be adequate to run your lathe.

There is a good chance the drive is tripping because the overload and motor parameters have not been set properly for the load you have connected. Have you read the setup procedures and adjusted the drive accordingly?

These devices do not work right out of the box.

Your motor must be connected for the proper line voltage.

The VFD will be a much better choice than the phase converter.

Stuart

Mr muddle · Apr 6, 2020

Its 240v supply voltage, I've adjusted the VFD inline with motor spec' I'll go through procedure again in hope I missed something.
Why would you rate the VFD over the rotary converter?
Thanks for all the help.

atomarc · Apr 6, 2020

The VFD will have built in over-current protection, variable speed, ramp up and ramp down as well as DC braking plus a million more tweeks. The phase converter has none of that. It's like comparing a Ferrari to a Yugo.

Stuart

SomeoneSomewhere · Apr 8, 2020

Could you please post/check:

* The actual error code on the VFD

* What the acceleration ramp time is

* Are you in V/f (AKA V/Hz) mode or vector?

* Make sure you have the motor wired for 240V

* Motor nameplate and VFD model.

* Make sure you have input phase loss protection disabled; this looks to be parameter H98 bit 1 if I am looking at the correct manual

EmGo · Apr 8, 2020

atomarc said:
The VFD will have built in over-current protection, variable speed, ramp up and ramp down as well as DC braking plus a million more tweeks. The phase converter has none of that. It's like comparing a Ferrari to a Yugo.

Imo, more like comparing a Ferrari to a Peterbilt.

Which one goes farther between failures ?

I admit, the Ferrari is nicer for picking up girls. But this is just a clunky old lathe

Froneck · Apr 8, 2020

You mentioned the VFD is not designed to pull in a contacter. You Right! The VFD must be connected directly to the motor. On/Off must be thru the VFD. Doing it any other way will ruin the VFD! As to which way is best I prefer the RPC made from another 3 phase motor! Used 3 phase motors are cheap and easily replaced. I have been using one I made for 10 years powering 6 lathes without any problems. In addition to the lathes it powers other type machinery also! I haven't had any problems yet, only replaced one capacitor! My connection is simple I do not use any Run or Balance Capacitors. Only Cap. I use is Start. The VFD does have nice features, can vary the speed along with other functions. However if you want to simply use the contacter to start the motor, clutch to run the spindle and provided gear selections for spindle speeds the RPC works! I prefer slower speed motors, 1200 RPM sync. motors work great. I do not use the 3600 RPM motors when making converters for friends. All those I made work great, no complaints nor have they need repair yet!

longrangejon · Apr 8, 2020

I have retrofitted many vfd's to existing 3 phase machines my preferred method is to take
single phase to the control transformer in control panel then take single phase to vfd then take 3 phase from vfd directly to the motor.
Now you have a forward and a reverse contactor in control panel.
take a set of contacts and run vfd control through it using one for forward command other for reverse.
this way all the safety features of existing machine will still function like original.
and not that hard to go back to original if the day ever comes when you have real 3 phase.
Thanks

SomeoneSomewhere · Apr 9, 2020

One issue with that is that VFDs are not necessarily safety rated, and if you want to use them for safety purposes you should really be connecting to the STO inputs.

Dsg wont go

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