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.

 

[Roy Costa]

I want to thank everyone for your input. So far, the Soft Starter had not tripped since I adjusted the back pressure and adjusted the setting on the Soft Starter. I explained what I did in my last post in the attachment. I have learned a lot from all of your input.

 

[waross]

And no at least I have never encountered the symptoms of too low voltage.
.....
.....
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.

Anna, I am usually impressed by both your technical knowledge and your practical knowledge.
But in this case, you have admitted that you have no knowledge or experience of the issue.
I will be glad to walk you through the theory, but as a mentor and not as an antagonist.
Should your plant ever have occasion to purchase 60 Hz equipment, you will be able to competently and confidently install and operate the equipment on your 50 Hz supply.

Low voltage hint: Look at this table from the Cowern papers to see the effect of low voltage on starting torque:

The motor is being fed with 410 Volts at 60 Hz.
It should be fed with 480 Volts at 60 Hz.
410 Volts is 85% of 480 Volts.
The torque may be expected to be .85[sup]2[/sup] of rated torque or 73% of rated torque.
The starting torque of a design "B" motor (the most common design) is about 150% of rated torque.
73% of that is 109% of rated torque.
The pull in torque may be as low as 120% of rated torque.
At the reduced voltage the pull in torque may be expected to be about 88% of rated torque.
A positive displacement pump starting against back pressure is basically a constant torque load.
That marginal 109% torque will be further reduced by the soft starter.
If the motor even starts to turn it may be unable to get past pull-up RPM before the soft starter nears the end of the start-up ramp.
By that time the I[sup]2[/sup]T of the locked rotor will be at or close to the trip setting.

When the ratio of volts to hertz stays constant, the
motor can be operated at the reduced frequency and
reduced voltage.

The corollary is true:
When the ratio of volts to hertz stays constant, the
motor can be operated at the increased frequency and
increased voltage.
Cowern Papers

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

 

[Roy Costa]

Still periodically tripping the soft starter. Nidec & Arisa are not working on it, onsite and remotely. I believe we need to do one of 2 things, use a VFD or bring in 480 VAC and tune the soft starter or replace it with another one with a higher volt/amp capacity. I do not believe they will be able to tune this one.

 

[waross]

The basics of frequency conversion: Keep the Volts per Hertz ratio the same.
You have increased the frequency in the ratio of 60Hz:50Hz or 6/5
You should increase the voltage in the same ratio.
6/5 x 400 Volts = 480 Volts.
With 480 Volts you will have the same torque as produced at 400 Volts, 50 Hertz.
By the way, the HP also changes with the change in frequency and voltage.
With the same V/Hz ratio (480 Volts at 60 Hz) the motor will produce the same torque but turn 6/5 times faster.
When you supply the motor with 480 Volts, you probably won't have to worry about hydraulic circuits nor pressure settings.
I would set the soft starter to as close to DOL starting as possible.


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

 

[Roy Costa]

Thanks Waross,

I will pass this on.

 

[RedSnake]

I am a bit curious, has this been a problem from the start the commissioning?
Or did it turn up later?
And who did the commissioning?
And who decided it was to be put on 410 Volt transformator?
Does it tripp at start?
Or after running a while?
How often do you stop and start that motor?
As I said before you can only start it 5 time an hour you need to wait at least 12 minutes so the starter can cool down, between starts.

That soft starter should be able to handle that motor if you put it on 480 Volts with the right settings, so I don't think you need to change it.
And if you can change the program so it starts on 35 bar it should definitely not be any problem with the SS on start up.



NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[waross]

I once converted an entire gravel processing plant from 50 Hz to 60 Hz.
The plant was imported from Europe.
It consisted of shaker screens, washing equipment and vibrators.
One vibrator was overloading slightly at the higher speed, The weights were adjustable and an adjustment of the weights fixed the problem.
As I have said, the first step was to calculate the V/Hz ratio of the motors and then set our generator voltage to the correct voltage.
Your motor will run faster, there is nothing short of the expense of a VFD that you can do about that, but that should not be a problem, seeing as I understand that the machine works OK if you can get the pump started without tripping the overloads.

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

 

[RedSnake]

Your motor will run faster, there is nothing short of the expense of a VFD that you can do about that,

Half true since the motors only function is to supply the hydraulic system via the pump with 40 liters/min.
By reducing the pressure on the pressure reducer 31 (130bar) you will be able to drain of the excess 8 liters that the higher rpm on the motor gives you.
So there is no need to use a VFD to make the motor go slower.

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[Roy Costa]

RedSnake,

We have been having this problem for months. And, there have been all kinds of problems with this press. The safety breaks on top of the press keep failing, and they have been replaced several times, and the only way to reset them is to turn off the lube systems to let them drain, (mechanical reset). All kinds of seals had to be replaced, (bolsters, etc.). Support is difficult, all the drawings are mostly in Spanish and I just got approved for the Siemens PLC software so I can use it to see the live code and look at what the permissives and interlocks are to troubleshoot. Spain is 6 hours ahead of us, so when we need support, we are out of luck if problems occur after their hours. And, even when we do have them, the there is a lot of misunderstanding because of the language difference. And, we had to depend on them remoting in, which at times causes profinet errors because of their connection.

I have all the drawings, however I got to dump them in google translator to read them, and, I had them print out the PLC code, however, it is all in spanish. It is one of the most complicated systems I have ever seen. The press cost $7 million dollars. It was designed to work in France on a 50 Hz system and they (we) have had nothing but problems with it. However, when it is running, it is very impressive. But, when it goes down, it is down.

Arisa & Nidec did the commissioning.

It only trips the OL and has all kinds of lube errors at the start up of the lube system. The motors shut off automatically after 1 hour if the press is not producing and we run 2 shifts, so we have to restart the motors after a die change, sometimes a roll change if there is problems and first thing in the morning.

 

[RedSnake]

In which way does the safety breaks cylinders break, is it the sealings?
What pressure do you have when you are driving the press in auto on the 31 (130bar) manometer?

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[edison123]

Ditch the SS for a 480 V VFD. Run it at the desired pump speed. No starting hiccups including inrush current.

Muthu

http://www.edison.co.in