Need some help troubleshooting soft starter overloads 9

[Roy Costa]

We are having some problems with having overloads on our soft starter that is connected to this motor.

We are feeding the Schneider Electric GVME22 motor starter with 410 VAC then it goes to the Siemens Sirius 3RW4026-1BB04 Soft Starter.
We keep getting overload trips on the soft starter and at times, we get overloads on the GVME22 motor starter. I thought the soft starter was going bad
So I switched it with the one next to it that is the exact same soft starter and I get the same results. The temperature on the FLIR reading the GVME22 is 90 degrees F.

Why do you think this is happening? Originally this Servo press was designed to be installed in a country that uses 50 Hz. However, the motor seems to be ok to run at 60 Hz according to the name plate
And the datasheet for this motor. Could it have something to do with us using 410 VAC? Or perhaps the settings on the soft starter?

See the attachment.

99% of the time the trip occurs when bringing up the press, at a cold start or if the press was shut off for 10 minutes and then trying to re-start the press.
It is a lube pump, so it is the first pump to turn on before the main motor is turned on, and the lube pump runs constantly.
The lube pump just pumps lube oil for the press. The lube oil is for the 2 giant servo motors, the RAM, bearings, gears, etc.

 

[RedSnake]

Yes they do.
But this is a S1 duty motor so it should not be started that often then it will go to warm.

But just starting it on the contactor isn't such a quickfix as it sounds apart from it still will have to work over it's ratings.
You need to redraw the electrical drawings and go through the PLC code and replace or fix all the places where the inputs from the soft starter is used and handle whatever turns up, most probably the HMI pictures needs to be remade and the outputs used to control the soft starter also needs to be reconnected to get the same functionality and all the hardwired stuff in the cabinet must be made for the same functionality.
It is quite a lot of work actually.

And since the motor starter also have been tripping I don't think this is the way to go.

Instead of taking it away, you could just put it at 100 % voltage, max current and 0 sek start time or something, it should be the same, don't think it will work though and I am not recommending it, the motor breaker will just tripp instead even though it is set to 2 amps more than recommended.

I do not think there is any way out of this more than reducing the torque/backpressure so the motor can work at it's ratings.



NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[waross]

but don't most motor starters and motors accept a short term high starting current?

Yes.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[moon161]

Is the lube oil pump centrifugal or displacement?

 

[RedSnake]

It is a gear pump.

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[Roy Costa]

Here is what I have today. Please read the attachment.

 

[waross]

I don't understand, maybe I missed something.
Why the insistence on starting against back pressure?
It seems to be quite easy to automatically dump back pressure before starting.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[RedSnake]

Well this dumping of the back pressure via the overload cylinders, even if it can be done it's time consuming and takes energi to have to fill them up again every time.
They should really never be dumped unless the ram can't turn in bottom dead center.
They are there to protect the rods and mechanic of the press if there are double sheets or the wrong die is inserted.

It would be much more effective to allow the YH2 to be set while the motor is starting then the back pressure would only be 35 bar and the balancing cylinder only takes 68cc/min so 10 seconds more or less wouldn't be a problem.

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[MintJulep]

Excellent job by RedSnake at diagnosing the problem.

Fundamentally, here is a problem that a lot of people seem to have.

We keep getting overload trips on the soft starter and at times, we get overloads on the GVME22 motor starter. I thought the soft starter was going bad

There's a device designed to detect motor overloads and shut the motor down when it does detect one. Or in this case, two devices designed to detect motor overloads.

When it does its job the first thing that many people think is "the overload detector must be broken."

Why? Shouldn't the first thing that crosses your mind be "my motor is overloaded!"

 

[waross]

I can't help thinking that 480 Volts and DOL would start the motor even against back pressure.
And I can't help but think that starting against back pressure needs lots of torque, which the soft starter may not provide initially.
I have to wonder if the pump does not start to turn until the soft starter has ramped up enough to provide enough torque.
I understand soft starters to start high inertial loads, which a hydraulic pump is not.
But I understand that I don't get to say.


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[MintJulep]

In this application I'd think about changing the soft starter to a VFD, set to run the motor at 50 Hz and whatever voltage that it's happy with.

Most VFDs have a programmable start ramp as well.

Ramping up against a stall doesn't seem like a great idea to me, but I'm a mechanical guy, so what do I know.

 

[RedSnake]

The whole hydraulic system setup is strange to me.
As you say waross starting a hydraulic pump with max load isn't common, even if it is doable, it is usually not how it is done.

Since the the torque curve is quite linear from 1000 rpm and upwards maybe the settings should be more like for an extruder that has the same load from start to finnish.

Then the settings on the soft starter should be something like this.

Trip class: 20 (maybe 15 will be enough)
Motor current: 18.8A Ie should be set to nameplate according to Sirius manuale.
Current limiting: Max (Will allow 18.8 x 6 = 112,8 amps at start if the amp goes higher the softstart will lower the Voltages out to the motor to keep the current below this value.
Two things here you might want to measure the max peak current when starting the motor this will give you an idea how to set the Current limit.
Or measure the voltage during start if it goes down somewhere during startup the current limit might be to low.
Ramp up time: ?? Seconds
This time might be measured even if the pressure is't linear with rpm the time should not be shorter than it takes to build pressure up to 105 bars which was the pressure at 18,86 amps.
It should never be longer the 15s according to ABBs general rules for a 4-pol motor size 160.
Starting voltage: 70%
Ramp down time: 0 Seconds

And also according to the Sirius manual you might need to give the softstarter a bit more space, don't really think this will solve the problem all together but it would be nicer for the starter.

With this soft starter you can't start the motor more than 5 times in an hour, when you where testing this new settings could it be that you didn't wait euomough between the starts to allow the soft starter and motor to cool down and that might have made it tripp?

Back to the hydraulics.

This pump, to call it a lubrication pump is a bit misleading even if it have that funktion too but only for lubrication you could have done with something much smaller.

In this system you have 4 pressure reducers.
1. pos 30 (130 bar) now 105 bar it is there only to prevent the motor or pump, in this case the motor to overheat or draw to much current, it is like a hydraulic safety valve, isch..
2. pos 60.1 (60 bar) for the table looking it is only at 60 bar when you want to drive the table out when doing die change.
3. pos 60.2 (35 bar) for the lubrication of the balancing cylinder.
The reason for reducing pressure here is not to press the lubrication oil pass the cylinder gasket that separates the piston and piston rod from the lubrication side and into the pneumatic cylinder filling it up with oil.
4. pos 60.3 (92 bar) overload cylinder system, this system only needs to be re-pressurized after a overload tripp when the cylinders are empty, as I said before the maximator will pump up the pressure higher depending on the settings in the PLC, if this pressure on this pressure reducer would be lower the same effect can be reached by increasing the air pressure to the maximator or with the same airpressuree it will just take longer.

For the lubrication that does not have pressure reducers as I said the amount needed in total is 2.166 liter/min.
That is why I say it's a bit misleading to call this a lubrication pump when it gives 48 liter/min.

I have a lubrication pump in our 800 ton hydraulic press.
It's really tiny and cute only 0,18 kW max 0,12 l/m but we only use 0,003 l/M the back pressure is set to 35 bar but it only works between 12-25 bar.
But as I said the pressure only need to be so high that it can push the oil to the highest point which in this case is about 8-10 meters.

And since the reducer for the balancing cylinder is set to 35 bar without having seen the press my assumption is that it is lubricated at the top which is most likely the highest point of the press.
Which means that 35 bars is enough to get the oil to all distributors.

So what does all of this mean.

Lets say the pump is running and you want to change the die.
To do that you need to drive the ram down to unlock it and then the overoad system needs to be ok.
If it is not then it needs to build the right pressure and you would have 92 bars in the lubrication system after that is done the ram can go down and to make one or two strokes with the ram the amount of oil that is already there on the balancing cylinder from the lubrication would be enough even if it doesn't start.
Then the die cart cylinders are raised and the pressure will be 60 bar until you have driven the table out and then back in again.
Ram down lock the die and the back up again.

So what would the pressure look like.

105->92->105-> (35 or 105)-> 60-> 105.

At production the same thing overload okey to drive ram down, lubrication okey (in my opinion) 35 bars would be enough.

105 -> 92 (if needed)-> 35 bar (in my opinion) if the 2HY isn't set all the time during production the pressure will be 105 bar and will only go down to 35 bar when lubrication is needed for the balancing cylinder.
But I can't see why it shouldn't be lubricated constantly during production.
Ours are.

I still think you should look at the the conditions for setting 2HY.
There is never a need for the system to work at 105 bar (130 bar) the max is 92 bar when the overload system needs to increase the pressure which should be "never" unless it has tripped.

So in my opinion the back pressure should be 35 bar as long as a die change is not going on or the overload has tripped.







NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[waross]

Early in my career I worked in a number of lumber mills.
All had hydraulic systems of around 10 HP to 15 HP.
All started DOL against back pressure.
Given that the manufacturer has apparently not encountered this issue with 50 Hz applications:
As I have said several times;
"The first step, the very first step, in a 50 Hz to 60 Hz conversion is to supply the correct voltage as per the V/Hz ratio."
With 410 Volts vs 480 Volts, the starting torque is already down to 73%.
The soft starter is probably making the starting torque even less.
"The first step.....
I appreciate your analysis of the operation of the press, Anna, but when the motor is showing the symptoms of low voltage and the voltage is low...???

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[RedSnake]

One does not exclude the other.
I have no opinion about changing to 480 volts.
Simply because I have no experience of that since I live in 50Hz 230 /400 volt country and all our motors are optimized for that.

I don't agree with changing it to direct online start I guess that is what you mean bu DOL?
Simply because it is to much work, and starting at full load would wear unnecessarily on the mechanics, waste energy and it is not necessary.

The reason it is not necessary is that while starting the motor neither the lubrication or the overload system or any other function this pump supplies is needed in the press.
So starting it against 35 bar back pressure is okay and will not damage the press.
After startup, before running production the lubrication need to be ok (35 bar should do it).
And after unlocking the ram the overload should be ok.
But if that need to be re-pressurized I would say there is something wrong with it, internal leakages or something.
But even if pressure there needs to be 92 bar for re-pressurized after start up it should not be a problem after the motor have started.

After that during ordinary production 35 bar should be enough for the lubrication.

The pressure reducer PRDM2BB21SVG15 even if fully open it can only drain 20 liters/ minutes so there would still be 28 liters per minutes left.
At 35 bar their with be more left.

And at die change 60 bars will be needed but there is no need for lubrication.

In theory this system motor(pump) should never run at 105 bars only max 92 bars at short intervals.

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[waross]

Simply because I have no experience of that since I live in 50Hz 230 /400 volt country and all our motors are optimized for that.

"I have no experience of that"
I have experience with that. Both 50 Hz to 60 Hz and 60 Hz to 50 Hz.

"I live in 50Hz 230 /400 volt country"
That's a V/Hz ratio of 8:1
At 60 Hz that is 480 Volts.
What would be your first reaction if you had a complaint of a 50Hz 230 /400 motor not starting properly and found that it was supplied with only 333 Volts?
That is analogous to running the 50 Hz motor on 410 Volts, 60 Hz.
Would you not strongly suggest applying the proper voltage before doing any other trouble shooting?
First step....
Volts per Hertz....
Been there, done that..


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[iop95]

At 410V, motor torque is reduced with 35-40% below nominal... so how can motor overcome load torque if this is above what motor can develop?
Motor starter is a controlled thyristors device, that reduce applied voltage to reduce initial start-up current; but voltage is already too low and motor can't accelerate (because torque is not enough) and current increase as starter increase applied voltage in specified ramp time; so current increase above max set current and trip is a normal event to protect motor...

Switch to 480V and all issue will be solved.
Or remove motor starter... but add a motor relay.

 

[RedSnake]

What would be your first reaction if you had a complaint of a 50Hz 230 /400 motor not starting properly and found that it was supplied with only 333 Volts?

I would have to call the power company, the largest in Sweden and ask what the h.ll they were up too.
That has never happened, the opposite have happened though but that is another story.

Would you not strongly suggest applying the proper voltage before doing any other troubles hooting?

I think you misunderstood me, maybe it is my Swedish humor?

I didn't strongly suggest applying the proper voltage first, because you already did.
So I didn't feel that I needed to confirm your statement, since I know you know these things better.
I have never needed to deal with this problem or even think about it and I will never have to.
So I just decided not to comment on it at all.
And I didn't disapprove or approve or agree or disagree with your suggestion to run the motor on 480 VAC.
Neither did I say do this first and then this second or do just this and not that.
When it came too starting the pump with 35 bar backpressure.

The only thing I disagreed with was changing the SS to a contactor and the reason for it is that, if this press had been sold in EU then making this change would render the manufacturer to make a new CE declaration.
It would be almost impossible to get the manufacturer to do that.
Doing it yourself, would mean, apart from all the work, that you would take on all the responsibility for the guarantee and safety for the press.

I have no clue what the rules are for this in North America or even in Michigan, but since I don't I rather say don't do it, and be safe than sorry.

And for trouble shooting before or after.
I don't see it as troubleshooting, I have been involved in buying 9 presses and several other machines at my company.
And mostly my job has been to confirm that we get what we have bought and is paying for in terms of dokumentation and function.
But doing this on every single thing/item isn't doable it would take forever.
So my mentor said look at every tenth ting and if you find many faults or some mayor ones you need to start looking at everything else too.
But to be able to do that you need to know the functionality of the machine so it more about that than troubleshooting.
You are going to have to live with this machine for many years so it isn't a waste doing it, sooner or later you need to anyway.

Maybe this was my mistake I should have asked Roy about this.
He said the press was bought and it wasn't made for the US market.
But he never said..
When it was installed?
And by who?
And who commissioned the machine?
And if this problem was there during commissioning?
Or if it turned up later?

My assumption was that if this would have happened during commissioning, at least I would have told the manufacturer or commissioner that you need to fix this otherwise you won't go home and you won't get payed.
So when Roy said that we got this problem I assumed it was something that had turned up later.

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[waross]

I would have to call the power company, the largest in Sweden and ask what the h.ll they were up too.

In this case the power company may answer;
"Your motor is rated for 460 Volts.
It is universal practice in North America to supply 480 Volts to 460 Volt rated motors.
Our smart meter shows that we are supplying a stable 480 Volts to your plant.
You, on the other hand, have instead opted to install a transformer supplying 410 Volts to the motor.
As there is nothing wrong with our 480 Volt service, you will be billed for a service call."

Am I the only one here who has ever done a frequency conversion?
Am I the only one here who is familiar with the symptoms of too low voltage? (Often due to line drop on too long branch circuit conductors.)

With 480 Volts supplied to the motor, the torque will increase by a factor of about 137%.
With 37% more torque (the same torque as would be produced by 410 Volts 50 Hz.) the motor will probably start with the original 50 Hz based settings on the soft starter.

Investigate Volts-per-Hertz for motors, transformers and other inductive devices.




--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[RedSnake]

Now everything becomes very hypothetically.
In Europe and Sweden we have 400VAC 50Hz so any motor I would put in would be rated 400/690V, 50hz, IE3 or if it is a small one 230/400V 50Hz IE3 that is EU standard.
And no at least I have never encountered the symptoms of too low voltage.
We have double incoming feeds from the water power station that is located less than 11 km from the factory.
So either there is power and it is correct or there is not.
Would say that at least here in Sweden it will never happen.
So for that reason I have never had to do a frequency conversion.

And why who ever it was that installed or commissioned this press in the States chose to put it on a 410 volts transformer only Roy may know.

This motor is a EU standard motor 400/690V, 50hz but the press can not have been intended for the EU market to begin with, because the motor was manufactured in 2019 and it has been forbidden to use IE2 motors here since 2017.

Where the settings on the soft starter comes from is unclear they don't correlate with any recommended settings for this motor regardless of the voltage supplied.

I will make a guess here and say that this press might have been intended for Russia reason being most drawings are made in Aug 2021 probably start of manufacturing but the hydraulic drawings were made in May 2022 either they were remade or finished but after that the deal for some reason fell through.


NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[edison123]

Show the motor some love. Give it some nourishing juice.

Muthu

http://www.edison.co.in

 

[Gr8blu]

Motors develop torque that is proportional to the square of the applied voltage. This means that if 410 is applied (and rated is 460), then the motor only produces (410/460)^2 * whatever the rated torque is for that speed point. In effect, the reduced voltage applied results in THE ENTIRE STARTING CURVE being 79% of the "expected" value, until the voltage is brought up to the correct operating value (i.e. 460 V).

The system has backpressure - it is how hydraulic systems are consistently operated (for the reasons given by RedSnake!). How much backpressure is present can be adjusted through judicious application of valving and oil viscosity. If the motor does not develop enough torque to overcome the load (i.e. the back pressure), it will continue to attempt to do so by ratcheting up the current draw from the starter. Eventually, either the backpressure is overcome and things go on about their normal lives, or the protection elements kick in and stop the process (in this case either on instantaneous overcurrent or on short time overcurrent - which is really current vs time).

The starter(s) are doing their job correctly, and the motor is trying to do its job correctly too. The system parameters (backpressure, current limits, "start time", etc.) are wrong for what the motor can actually accomplish - or the protection is set too close to running values to allow the start sequence.

The big question is that when supplying 410 to the Schneider device, what voltage(s) appear at the terminals of the Siemens device and the motor itself? At the beginning of this discussion, I assumed that 410 appeared at the motor terminals as well, but I could be wrong. If it's lower, the developed torque is also lower and the motor (driving the pump) less likely to overcome the existing backpressure.

Converting energy to motion for more than half a century