Inverter problem

I used my lathe today it has a Jaguar Club Inverter fitted.

When using it the power was fluctuating noted on the inverter and sound of the motor.

LU came up on the inverter, looking at the manual it states undervoltage protection.

Any help please.

Thanks Bob.

Edited By BOB BLACKSHAW on 15/07/2018 12:56:55

That’s generally on your supply in

Check your wiring to the inverter and your supply (3 pin plug) or breaker

You may have generally low voltage in your area. Check parameters in the drive to check its set to 230v

You might have to have a word with your power company. I often had low power problems when I first came to this part of NZ in the early 80s, the voltage at times would go down to 185V. A new substation was built in the 1990s, and since then standard voltage has been held even though the population has at least doubled.

Ian S C

I have in the past had a problem with under voltage at a factory I worked at I have a meter with a trend plot and so was able to tell the supplier as they would not believe we had a problem and they had to put a generator in to supply the factory for just over three months till they could upgrade the sub station. If you have a problem the supplier has to fix the problem as it could be a safety issue. It should be 230v +10%  -6% 

David

Edited By David George 1 on 15/07/2018 17:02:38

Is your supply single or three phase? If it is three you may have dropped a phase. It could be a capacitor problem as I suspect they actually measure the voltage of the DC link rather than the actual line supply. If you can look at the caps make sure they are not bulging and they are well soldered to the board, make sure there are no cracks between the tag and the solder and no movement.

Mike

Hello all,

Its single phase, but this afternoon the Inverter been working correctly,this must of been sum sort of drop in supply,

Thanks for all of the replies.

The model engineering forum is top marks for input, I have a MGB and only get usually one or no replies with some problems I have on the MGB forum.

Perhaps try here in future.

Again Thanks, Bob.

What MGB do you have Bob perhaps some pictures would help is it single or three phase.

David

My industrial experience with single phase input inverters tell me that a trip on under link voltage is supply voltage.

We once set one up to record dips in supply voltage at night, as the ups on the main file server was going on to battery supply the shutting server down. The electricity supplied then loaned us a log file recorder, it was local transformer fault.

I am still having problems with the inverter with a drop in the 50hz which is varying the speed of the motor.

I contacted the power network at 5.00pm and a engineer came at my house a 10.00pm. The engineer had a look at the inverter and the 50hz dropped to 49.2hz then went back to normal, so he could see the problem.

He checked my supply under load and the voltage was 244 -1, then checked the ELI which was 0.3 ohms, he was happy that the supply was not the problem and a voltage checker over two weeks was not needed.

Any other ideas what the problem could be, as the Inverter supplier is convinced that its a supply problem.

Thanks Bob

Shouldn't be a supply problem when running at 50Hz. By the very nature of the input rectifier and capacitor bank that supply the inverter there will be rather more than nominal mains voltage available at the DC bus from which the AC drive is generated. Maybe 330 volts or so. At 50 Hz the motor will be running at its design speed and, crudely, only needs normal mains voltage. Nominal 230 volts with tolerances as given by David above. So theoretically the DC bus could drop to around 180 volts before the VFD has problems driving the motor at 50Hz. Reality is (much) more complex but thats near enuf to give you the idea.

VFD needs the voltage headroom to help hold up torque when you change the speed. Which is where it starts getting at least complicated, usually really complicated. All sorts of reasons why its not good to run a VFD with an under voltage input and DC bus. Which is why the devices are made to flag up a warning even though its capable of running OK "right now".

Clive.

Very unlikely there's a problem with the supply - and even then the supply frequency is of no consequence. Your other equipment would probably be complaining too.

Sounds like a dodgy local connection, quite possibly within the VFD itself. Worth checking the connections in the terminal block but it's also possible something has come loose internally. You might take a look under the covers if you feel up to it.

Let it develop and see what happens if you haven't a spare. Just don't leave it running under load when you're not present (seems very unlikely), as an intermittent connection could become hot and present a fire risk. Sounds more like an annoyance at this stage though.

Murray

Is this problem new or still associated with the LU error mentioned earlier?

The engineer visit has eliminated some, but not all, of the causes of under-voltage on the input side. From the manual, things to try and check:

Dave

PS Fairly confident the frequency variation is the VFD output, not the supply input.

Edited By SillyOldDuffer on 28/07/2018 12:10:13

Thanks for the replies.

As for Dave reply it first showed LU error on the 15th of July when I first noticed the problem, now no LU is shown on the inverter.

I shall have a look at all the connections and see what happens.

Bob.

Bob,

This may be a red herring, but I post it here in case it helps.

What setting have you got for acceleration to speed and deceleration to stop? On my vfd they are parameters 014 and 015. In my ignorance in setting up up my ( first ) vfd, I set the acceleration and deceleration times to 2.5 secs. I also got an input under volt error code. Setting them to 10 seconds solved that problem. Possibly unconnected to your problem, just thought I'd mention it.

John

Regarding Johns post,

The instruction manual for the VDF is quite involved for me but I will check this out, thanks.

Measure the voltage at peak and non peak times.

Vaery rarely mine drops to 245v unless in peak times but used to go up to 266v non peak, generator across the road.

Is it possible the storage capacitors are wearing out?

They are designed to be replaced after long periods of use, but can also degrade if unused for long periods.

Most VFDs have a complicated range of configuration options that allow them to be adapted to a wide range of motors and circumstances. The best written manuals are intimidating not least because, in the detail, they assume the reader is a specialist who knows what he's doing. A few hundred pages of terse jargon to decode, yuk.

The complexity of a VFD inside the black box can make fault-finding difficult. Not only could there be a fault with the wiring, or the motor, or the electronics, it is also possible that the VFD has been misconfigured in software. If it's been told by the user to behave badly, it will!

Programmable devices are often configured incorrectly by mistake even by experts. You find a setting in the manual on page 47 that looks to do what you want, without realising that page 183 explains other changes are necessary as well. This is assuming that the manual makes sense in the first place! Whenever the configuration is changed by the user, it's essential to double check it's right. It's also possible for configuration settings to be corrupted by power spikes, brown-outs, software bugs, or even alpha particles!

Configuration problems are so common that most devices provide a simple way of restoring the factory defaults. These are carefully thought out to cover common situations and guarantee the configuration will be in a sensible state before modifications are made.

If Bob is still seeing misbehaviour after eliminating other possibilities, I suggest resetting the VFD to Factory Defaults and starting again. Setting H03=1 should do the trick. (see Manual page 5-39) Once the VFD is back to a known state, see how the motor behaves, then ask again for advice about changing configuration settings to match a particular motor.

Dave