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.

 

[edison123]

"What if I run a separate feed just for this motor? A 480-volt feed to the top of the motor starter that feeds the soft starter."

There you go. SS can take 480 V input.

Muthu

http://www.edison.co.in

 

[waross]

What if I run a separate feed just for this motor? A 480-volt feed to the top of the motor starter that feeds the soft starter.

Great idea Roy.
That earns you a star.

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

 

[waross]

So why is the torque the same for all 50Hz applications on this motor?

First, I didn't write the nameplate.
Second, I said peak torque and you are asking about rated torque.
Third, The available torque is what the manufacturer says it is.
And a couple of more questions:
First, Why does the rated current change when the voltage changes? If the winding will safely carry 20.7 Amps at 400 Volts whay will it not carry 20.7 Amps at 415 Volts?
Answer: It will safely carry 20.7 Amps at 415 Volts but then it will also develop more than 11.00 kW.
Second: When a 50 Hz motor is used on the proper voltage 60 Hz, it develops 20% more HP. Why is this not shown on the nameplate?
Answer:11.00 kW is more important to the nameplate writer than reality.
Notice that the rated torque drops from 71.7 Nm to 59.3 Nm at 60 Hz.
Does that mean that the motor may not carry the load on 60 Hz.
No, that nameplate is fantasy.
The reality is that the motor will develop 71.7 Nm when running on 480 Volts, 60 Hertz.
The motor will safely draw 20.7 Amps when the load demands 71.7 Nm.
That is the reality,despite the fantasy of the name plate.
(This story is real. Only the name (plates) have been changed to protect the guilty.)* paraphrased from the introduction to the an old radio series. Possibly Dragnet?
Remember; The peak torque may be 200% to 250% of rated torque. The nameplate writer has a lot of headroom to fiddle with the numbers for the rated torque.

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

 

[Roy Costa]

I came in this morning and the operator could not run the press becuase the lube system kept getting overloads trips on the soft starter. We reset the soft starter and I asked the operator to trip this function called overload that would dump the back pressure. After doing this, the press was able to come up normally without any overload trips. It is obvious that the higher rpm and the 130 bar set point is causing the back pressure. I am preparing a report to send to the manufacture and ask them to come onsite and make the adjustments to account for the back pressure. I am also going to suggest running a seperat 480 VAC feed to the top of the motor starter that feeds the soft starter.

Thanks everyone for your suggestions.

 

[RedSnake]

Well this overload system I didn't see that it was connected to the same pump as the lubrication.
Looking at the hydraulic drawings I can't see a good reason why the soft starter doesn't not trip if you turn of the overload system, unless you have to little oil in the system all together and the cylinders re drained back to tank when you turn it off, but then you should have other fault messages.
The 1750 psi (120bar) the operator says he needs that is shown here (green)

does not come from the 11kW pump but is produced by the maximator pump here (blue)..

Now I am guessing since I do not have the PLC code or the electrical drawings, my guess is that when you turn of the overload till valve is closed meaning you do provide oil to the overload system, whether or not any oil is drained out of it and back to the tank I don't know?

It still doesn't explain your problem with the tripping of the soft starter and why it doesn't with the overload system off.

At first startup and if the overload cylinders are empty it will ofcourse take a bit longer to fill them up and then oil needs to be shared with the lubrication distributors and it will take a bit longer to get a signal back from all of them that they are functioning and ready.
But this in itself should not make the soft starter tripp.

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[Roy Costa]

RedSnake,

I have attached a picture of the actual after reseting by the OL switch, that in turn dumpted the back pressure, then the overload on the soft starter would not trip. They were able to bring the press up after that.

 

[edison123]

Redsnake - Great tips. I have learnt something about hydraulic diagram.

Muthu

http://www.edison.co.in

 

[waross]

A combination of low voltage and starting against back pressure.
That is a recipe for overload trips.
An analogy may be a domestic refrigerator that will not start against back pressure but will trip the thermal protection repeatedly until the back pressure bleeds off.
An added line of code to dump accumulator pressure before starting may be part of the solution.

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

 

[Roy Costa]

I agree, the manufacture disagrees and will be sending someone here tomarrow.

 

[waross]

Good luck.

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

 

[RedSnake]

Hmm not sure I actually understand what you mean by "reseting by the OL switch" is the OL switch this one?

From the general condition chain you need the following (Of Course without PLc code or El circuit drawings I am "guessing")

Overload switch In ON position.
The cam/ram in Top Dead Center (TDC)
Reply from all lubrication distributors that they have received oil usually done with induktiv sensors felling the main piston going up from the oil pressure.

The ram needs to be unlocked.

Then when all this is okey there might be two options..
Either it is the PLC that sets the oil valve =12-YH5 when the above the conditions are met.
Or the operator are supposed to push the Reset button seems less lightly though..
After this point the "Oil Pressure OK" value should show ca 1335 psi (92bar)

And keep on increasing up to the value set to say "Oil Pressure OK" 2147 psi (148 bar) or whatever is set in the PLC,
But this increase from 92 bar to > 148 bar is done by the Maximator and it needs air pressure to do it.
According to drawing 3.68 bar which seems correct if you truly have that.

Hmmmmmmmm... I think I see why this is happening......

In this picture the valves have emptied the overload cylinders.
So when you start the pump again they need to be filed up, as long as the the flow have somewhere to go the pressure increase will next to nothing much lower than 92 bar at pos 60.3 if it takes longer to fill up the cylinders and start pressure than it takes to start the pump the soft starter wont tripp.

Another way of solving this at least until a permanent solution for the root cause is fixed would be to set this valve YH2 for the ram balancing cylinder to 1 for 10 seconds when the pump is started the the back pressure would only be 35 bar.

It might not be right but I think it would work.


NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[Roy Costa]

RedSnake,

The press manufacture still thinks the problem is with the softstarter. They are sending a support engineer to install a new motor starter and a soft starter. Very frustrating.
They will see for themselves this is useless. They need to do those things that you and a few others suggested. Thinking that changing those starters will fix it is like
thinking you can change the music by replacing the speaker. They will find out.

And yes, the over load switch is the one you showed the picture of. After setting it to the off position for 20 seconds and then back to the on position, they was able to run the pumps and group lubrication circuits without tripping any overloads, hense, the OL switch dumpted the back pressure.

 

[RedSnake]

Okey
Let us know how things work out.

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[Roy Costa]

Will do, thanks again.

 

[Roy Costa]

The service engineer from Nidec came in yesterday and was set on just replacing the motor starter and the soft starter. He was present to witness the soft starter overloading at start up and after using the hydraulic OL button to release the back pressure and reseting the soft starter OL, he is convienced that changing the starters will not fix the problem. He, did agree with me that if we supply 480 VAC to that circuit to bring the motor to what the motor name plate states, the same problem will be there until we change the hydraulic settings after the pump. If we change the settings to 110 bar, he says that we would have to go to ever place where there is a lubrication point and make sure they are getting the designed lubrication and make adjustments or replace parts as needed. Nidec is reluctant to do that.

The other option would be to add a NO BIT in the place that would trigger a TON delay for 500ms that would come on when the lube pump button is pressed that would trigger the hydraulic OL circuit just as you would do from the PCM panel. That would dump the back pressure just before the lube pump turns on.

By the way, the back pressure reguator is set to 121 bar, not 130 bar according to ARISA's drawings.

 

[RedSnake]

I do not think you will have a problem with the lubrication if you turn the pressure down until you get around 18 Amps on the motor.

The function that requires most pressure is the overload system and that is at most 92 bar so you can't go lower than that.
Or actually you could if needed, the maximator would still build the same pressure but it would just take longer.
But I don't think you need to go that low.

The pump have a flow of 48 liter/min at 60Hz
All the lubrication distributors together needs 2.166 liter/min.
300 cc/min *6 + 240cc/min + 58cc/min + 68cc/min.
So you will still have more than 45 liters/minutes for all other functions and that is still 5 liters more than the total if you had, had a 50Hz system.

You still need to measure all the lubrication flows as he says to confirm.
The only pressure required for the lubrication is to push the oil to the highest point and overcome the distributors internal backpressure, how much that is I don't know.
But the flow isn't a problem here.


NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[LittleInch]

Or just remove the soft starter and start this pump DOL?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[RedSnake]

Hmm well I am no big fan of soft starters (I am an old fashion girl ;-) ).
We do have 11 kW hydraulic pump that we start just with a contactor, no problem.
But that one only have a back pressure at 45 bar so it never starts with full load, maxload is 200 bar.

Even starting the pump with just a contactor, you would still run the motor above the documented amps from the manufacturer.
So you would still just have solved half the problem.

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[Roy Costa]

I agree with both RedSnake and LittleInch. I will suggest removing the soft starter.

 

[LittleInch]

It's not the best thing for sure, but don't most motor starters and motors accept a short term high starting current?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.