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]

1. There is no attachment.
2. Does it tripp om startup or while running?
3. Is the motor running constantly or intermittently?
4. What is the motor running/supplying?

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[Roy Costa]

RedSnake,

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.

I double checked, and am sure now that there is an attachment.

 

[RedSnake]

One difference is that you have 20% more flow from the pump since the motors rpm is 1765 instead of 1463 which mean you will have a higher back pressure in the hydraulic system too, especially if the oil is cold, but since it trips after restart it's probably not a problem with cold oil.

If the pump or the system have any kind of pressure reduction valve maybe it isn't large enough to handle the extra flow?
Hard to say without a hydraulic drawing.
I think if you can measure the pressure in the luberivations system at startup and also the start current that might tell you if this is the problem.

According to the manuel 13.2.2 the Current limiting should be 4 and Starting voltage: 40% but of course it's just a recommendation.

https://cache.industry.siemens.com/...4/v3/Manual_softstarter_3RW30_3RW40_en-US.pdf

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[Roy Costa]

You could be right about the extra load on the motor circuit caused by the higher rpm and possible oil flow restrictions, being it was designed for 50 Hz. I do not understand hydraulics very much, so I uploaded the hydraulic drawings. There are 3 of them, and it looks like I can only upload one at a time.

 

[Roy Costa]

Here is the second file

 

[Roy Costa]

Here is the 3rd file.

 

[RedSnake]

It looks like the system is made to be able to handle both 50Hz and 60Hz running.

Pump pos 5 ALP2-D-40 MARZOCCHI
But according to the pump manufacturer the absorbed power at 130 bar is around 10kW at ca.1476 rpm.
But as high as 12kW at ca 1765 rpm, meaning the motor is running at max at all times if the pressure is at 130 bar which you also show on your amperemeter in the photo 21.11Amp.
Even though the motor should run at max 18.8 A at 11 kW.

https://www.marzocchipompe.com/sites/default/files/public-downloads/SERIE-ALP-MARZOCCHI-POMPE.pdf

I would start by measuring all the pressures to see so that everything is set right.
You should have 60 bar at measure point 32.8
And no more then 130 bar at measure point 27.3 not even at startup.
And if you bypass the filter at pos 42 the pressure drop should be less then 5 bars at manometer 27.3 otherwise your filter is full and the filter guard is not working right.

But I think your main problem is that the the pressure limiter should be set to 110 bar or something like that so that the power outtake is in line with the motor power.
You should ask the press manufacturer if there will be a problem if you set the pressure limiter pos 31 to ca 100 - 110 bar.

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[waross]

Thanks for posting the drawings Red.
It seems strange that the motor nameplate shows higher max current at 50 Hz than at 60 Hz.
Intuition says that there will be more cooling at 60 Hz to possibly allow a slightly higher current at 60 Hz speed.
Just saying.
I agree with the 110 bar setting.

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

 

[LittleInch]

With a reduced voltage is the pump even moving? Are you getting a locked rotor because there isn't enough torque to turn the pump if you still have 110 bar on the other side?

Why do have a soft starter for a 10kW motor?

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

 

[waross]

Could it have something to do with us using 410 VAC?

Probably.
410 Volts on a motor that wants 440 to 460 Volts and a starting voltage of 40% of a voltage that is almost 10% low to start with?



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

 

[waross]

With a reduced voltage is the pump even moving?

Good observation. I agree.

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

 

[Roy Costa]

I agree with all of you, in other places in the factory, our bus voltage is 480. We are using a special transformer on this Servo press for some reason.

This press was designed and built to run in a country that uses 50 Hz. and was sold to someone in Europe who backed out of the sale and we got it at a reduced price of $7 Million.

The press is a 1500 Ton ARISA and they are in Spain. The company in America who services it is called Nidec. They are telling me that the soft starter is bad, even though I had swapped it out with another soft starter that is exactly the same and it is doing the same thing, keeps popping the over load and the one that was tripping before, is not tripping. They want to send a new soft starter, "which does not make sense to me". I do not know much about hydraulics, I am a Controls Systems Engineer, and I do not know why they are not listening to me. The voltage should be higher, then the amps would be lower. And, if the hydraulic systems was designed to operate at 415 volts in a 50 Hz country, then the RPM would be 1467 at 20.1 volts. The hydraulic drawing show that the flow and the pressure in the system is regulated. So, running this in a 60 Hz country, at 410 volts, the amps indeed would be higher and the RPMs would be around 1765 which would increase the pressure and flow. I agree with Redsnake. I am going to take some pressure readings at the points where he suggested and present these findings to ARISA and Nidec.

And to answer Littleinch, I do not know why they are using a soft starter other than to control timing, and the motor is rated at 11kW. It has to do something with the 130 bar settings.

In the last attachment that I just uploaded, the pressure in picture 4 has to be showing 1750 psi and it will not climb until we turn off the overload button noted in picture 5, which dumps the back pressure so it can rise. (at least that is what the press operator told me), and this is an unconventional thing he does to get the pressure to rise so he can reset all the lube faults and get the pressure reading to start showing in the screen on picture 3 under the collum Real.

I wish I understood more about the hydraulics. For now, I will spot measure all the pressure points Redsnake suggested and compile a report and send it to ARISA and Nidec.

Thank you everyone for your help.

 

[RedSnake]

His setting is 50%, 40% was suggested in the Siemens manual for hydraulic pumps.
Maybe setting it up to 55%-60%
Maybe even shortening the ramptime a bit.
And the setting for Motor current was 25A should only be ca. 18 A

Another funny thing is that according to ABB there is no values for 60hz 415 Volt

https://www.electricautomationnetwork.com/PDF/PIM/ABB/EN_3GAA162410-BDF.pdf

Only for 460 volt.

At 60Hz 460 volt the motor can deliver 59.30 Nm I am guessing it is the same at 410 Volt.
The pump needs around 63 Nm to be able to deliver 130 bar.
At 50 Hz the motor will give 71.70 Nm which is enough.
Still think the max pressure will have to come down for this to work.



NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[RedSnake]

I do not know much about hydraulics, I am a Controls Systems Engineer, and I do not know why they are not listening to me.

If you refer to ARISA it's because they are Spaniards. ;-)

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[RedSnake]

I agree with Redsnake. I am going to take some pressure readings at the points where he she suggested and present these findings to ARISA and Nidec.

;-)

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[waross]

The first step in trouble shooting a motor is to check the voltage.
When the frequency is changed, the voltage must be changed in the same ratio.
This is the first step.
Get the proper voltage to the machine before worrying about anything else.
The motor is rated at 460 Volts at 60 Hz.
460 Volts is a standard North American motor voltage.
460 Volt rated motors are normally fed from 480 Volt systems.
This is to allow line drop in the motor feeder conductors.

I agree with all of you, in other places in the factory, our bus voltage is 480. We are using a special transformer on this Servo press for some reason.

It seems to be a no-brainer to get rid of the transformer and feed 480 Volts to a 460 Volt motor like the rest of the continent does.
Once you have the proper voltage to the motor, we can deal with any other problems.
BUT:
It may be wise to investigate the other components to determine their suitability for operation at multiples of 120 Volts, 60 Hz.
Hopefully the components will be dual rated for 50/60Hz.
Particularly check the drivers for the servo motors.

At 60Hz 460 volt the motor can deliver 59.30 Nm I am guessing it is the same at 410 Volt.

Bad guess.
Voltage below proper voltage = magnetizing current and field strength below proper field strength = peak torque and continuous torque below proper torque.

When you check components:
Any coils, relays, solenoids, induction motors etc; should have the voltage raised in proportion to the rise in frequency.
Any rectifying components should probably be fed with 110 Volts regardless of frequency.
If the servo drives rectify the input voltage and then invert the DC back to AC, they should be fed the same voltage (410 Volts) regardless of the frequency.
The drive will match the output voltage to the output frequency. (Subject to correction by the servo experts here.)

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

 

[RedSnake]

Bad guess.
Voltage below proper voltage = magnetizing current and field strength below proper field strength = peak torque and continuous torque below proper torque.

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

NAFO Sergeant Anna Gr 69th Sniffing Brigade

 

[Roy Costa]

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. "Would the difference of 20 VAC be a problem?" It is not Delta, so there is no wild leg.

Of course, after I first verify the pressure readings and if the manufacture agrees, then change the settings from 130 bar to 110 bar.
By the way, it is not a servo motor.

 

[edison123]

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

Because Power ∝ Speed x Torque. Since the power and speed (or Hz) remain the same, torque remains the same. That table merely shows how the motor can be configured for different supply voltages for the same speed (or Hz) and KW.

OP, since you already have 480 V, 60 Hz, run a 480 V supply to your soft starter bypassing the special transformer and see what happens.

Muthu

http://www.edison.co.in