Simoreg DC Master drive problem

[cjd1965]

DBeauvis
What I meant was to pass the whole ball to someone like Eurotherm.... I appreciate the Siemens drives were cheaper than a rebuild but how much would a new Eurtoherm drive have cost?

I was suggesting you could have asked them to diagnose the original drive problems, then acted on their recommendation, especially if your own guy is no au fait with DC kit.

They could have said, yeah, this drive is no good etc, xxxx dollars buys a modern version plus commisioning costs, then you would have a large drive company to yell at

Have had my rear end on the fire a few times I learnt quickly to wear asbestos pants lol
Obviously it sounds like the drive is running hot but finding the root cause is not gonna be easy


Best of luck.

 

[Dbeauvais]

cjd1965,

Unfortunately you can't buy this Eurotherm drive any more because it is too out of date. That was my original intent. All we did was blow a capacitor but the rebuild was $7,000.00 US and the new Siemens was under $5,000.00 US

 

[rdrast]

One more question... Thinking on the age of the original drive... Was the original SSD/Eurotherm/SSD/Parker (too many different owners there) ANALOG or DIGITAL ?

The new one is obviously digital, there is always a slight chance that you are getting electrical noise into the new drive, which potentially could affect it, and which might not have been apparent on an analog drive.

 

[Dbeauvais]

Model No. 590/1400/ and about another 30 numbers. I see plenty of both analog & digital references on the front of the drive under a System port (P3) over the analog section, Aux Serial port (P2) heading over the digital. It is divided in 3 parts with one group being analog and 2 being digital. Sorry not an electrician.

 

[cjd1965]

lol ....... did you price up a eurotherm?

SSD Drives was bought by Eurotherm, managment buyout from Eurotherm became SSD again, then Parker bought SSD...

same guys in mainly same offices etc. I see same sales man for 20 yrs with different business cards for same stuff.

590 is still available as the 590+ which would probably do the job OK and eurotherm guy would have set it up the same for you.

Water under the brige now, just curious.

So to clarify earlier point, you say the drive installer/commisioning guy says the motor is 'bad'... what tests did they do to confirm that, and did they produce a site visit report detailing any tests and the test results?

Have you spoken with Siemens about this? Their drive engineers in UK approx £800 a day to visit a site... ouch

Are you fitting more amp meters like leifmotif suggested? Is the motor generally running at a fixed speed once it has ramped up?

 

[Dbeauvais]

I have been dealing with this press manufacturer for 10 years and for the most part it has been an honest relationship. Since I do not know motors, controls and drives I trusted their judgement on the Siemens drive. He said the field was degrading but offered nothing written. Myt maintenance man was with him when he tested. My maintenance man is pretty talented but not degreed. The commisioning person did not have a megameter though. He put an amp meter on the field. I'm attemping to find a qualified DC motor company to get a second opinion. I have used people in town before with questionable results. Yes, once we ramp up the motor is always at a fixed speed. Top speed is 1200 feet per minute and that is where we run is paper lets us.

 

[Dbeauvais]

DickDV,

We talked to a motor shop and got some instructions on how to check a couple things. If I type something totally ignorant just tell me. The name plate does not give ohms. The field voltage is 360 and amps 5.95 so we should be at 60.6 ohms. Our amp meter showed 40.7 ohms. I beleive this confirms the field is degrading. We are running at top speed right now (1200 feet per minute) and my guy checked and our current is at 67% and armature at 1.3 amps. Our meter is quite old and I told my guy to go out and get a new one.

I found Spina Electric on the Internet and they conform to IEEE, EASA and ISO repair standards. Most of the shops in Detroit are here for auto business and I was always told they have a tough time with printing press motors (especially the German ones). When I mentioned to Spina that this motor was a Thrigge Scott he told me right away they are harder to work on. This concerned me.

The press manufacturer that I bought the drives from came out and put the second drive in and made some adjustments (I assume). No speed overshoots now, no over heating issues . . . how is that possible? He evidently had to re-tune the drive to the motor but wouldn't he have had to do that the first time as well? I would seem logical to me in order to properly install a new digital drive that you would first have to check the motor carefully and its field.

Can a failing degrading motor field do damage to a new drive? Obviously I'm assuming it was programmed properly in the first place. If in fact the motor did do something I must be damaging the back up.

Your thoughts are appreciated if you are not too sick and tired of this thread.

 

[cjd1965]

Hi
I think you answered your own question. If it is running 'sweet' with the 2nd drive since your contractor came and fitted it and commisioned it, and the motor is 'as was' then it can only be a drive hardware fault with the first siemens drive (unlikely due to factory testing) or a parameter setting issue that was corrected during drive swap (possibility #1) or you disturbed some other bad connection etc changing the drive out (possibility #2).
Has the ******t temperature cooled?

My question regarding the speed was really directed at the drive armature and field currents, which should be reasonably steady once you hit 'fixed speed' provided everything else is OK and could be checked

Ifr you rely on this motor for your livlihood I would still get a reputable company (ask DickDV for recommendations he is in the business of drives) to check out your motor so you know it is going to last you (or not) and you can plan a contingency.

Glad you have had some luck at last

 

[DickDV]

Dbeauvais, it is normal for a COLD field to measure low resistance so I would not automatically conclude that the field is degraded without knowing the temperature.

It would be much better (and you can do this on the fly) to measure the hot field resistance by letting the motor run up to temperature and then measure the voltage at the F1 and F2 leads at the motor and simultaneously measure the DC field current with a clamp-on DC ammeter. You can divide the two to get hot resistance.

If the drive has a field regulator, then the most important thing is the field current. Regardless of the ohms or volts, having 5.95amps of field current is pretty important whether the motor is hot or cold.

 

[Dbeauvais]

Thanks DickDV. We did measure the low resistance with a warm motor, we had just finshed a long run. I have someone coming in for a complete test. Beech Services in Dearborn.

 

[Dbeauvais]

cjd1965,

I had someone out today that I thought was very good with DC motors and I would like to run something by you. He was a nice older Frenchman that was hard to understand plus he was talking motor/drive technical stuff. He said the armature looked perfect, clean and no arcing whatsoever. He ohmed out the motor and found everything normal. He did not use a megameter because the readings would be influenced by dust. He could meg it in the shop once cleaned but he saw no need to waste the money, the motor was fine.

He claimed he was 99% sure that the 4 coils were wired parallel with each coil at 30 ohm. When wired this way you get different readings that could lead someone to think the field was bad. That is why the first guy read the degrading field. He could not be 100% without tearing the motor apart but as said, he was 99% sure.

Now here's my question. If the first drive was installed and everyone looked at the name plate and saw 360 V & 5.95 A and divided to get 60.5 ohms and set the drive up for that condition could the drive's parameters cause heating and speed overshooting? Then they came back out and installed the 2nd drive they measured the field first. They then noticed the reduced numbers and changed the drive parameters and the press has been purring like a kitten sice.

I also asked if the heat build up in the un-fanned cabinet could cause the drive to act up and he said yes.

Doug

 

[DickDV]

What still isn't really clear is why the field wouldn't be 360V and 5.95amps if that's what the nameplate says. Assuming the drive field supply can produce 360V, the shunt field should be wired up properly so it, in fact, matches the nameplate. With the field coils wired some other way, the drive would have to be programmed very specifically to match the change. Without that, either the field coils or the drive field supply could be at risk.

I would think that the drive on a printing press would have an active field regulator so, when properly programmed, the 5.95amps is always maintained regardless of motor temp or field winding resistance.

There's just too many things here that don't seem to fit. At least, it sounds like the motor windings are ok. They might not be wired correctly and the drive might not be programmed correctly but, at least the motor is not damaged.

 

[cjd1965]

Hi Doug
I am not an expert on DC drives and have never worke with a Simoreg.

However I agree with DickDV. The nameplate says 360V and 5.95A , therefore the resistance is 60.7 ohms.

You say the actual field resistance is 4 off 30 ohm coils in parallel, which is actually 7.5 ohms.

Therefore I = V/R = 360/7.5 = 48 amps........ this additional current would cause heating and maybe the drive was going into current limiting situations

Has the motor field windings been messed with at any time... obviously 2 of your coils in series would give you 60 ohms, which puts you in the right ball park.

My instinct tells me that the contractor did a wiring change or parameter change to cover up the original goof but doesnt want to admit any liability, and unless you got a parameter listing from them after the 1st drive was swapped out you are out of luck.

Some places I go the customer has someone wtching you like a hawk when you are on site.... did you have a guy doing that? Did they see what was done.

Cheers

 

[Dbeauvais]

DickDV,

Very strange if this motor is wired that way. I guess the nameplate could be wrong. The Frenchman that came out here was sure it was wired this way therefore the resistance number being low. I know you are sure that the 5.95 amps be maintained whether hot or cold but this guy said these motors can deviate depending on the the motor temp. Could that be because of the parallel wiring? Why would a motor company wire parallel instead of in a series? Someone said for dual voltage but the nameplate just says 360. Well the manufacturer has all the motor numbers and they can get with Thrige-Scott (unless the wrong plate was put on). I'll say one thing, I have never called in a motor company in and have them say "Don't waste your money sending your motor into the shop, it's completely fine." Most would try to at least sell some PM, cleaning, etc.

 

[DickDV]

It is not uncommon to break up the shunt field windings into pieces so various voltages can be accommodated. Typical would be one section of shunt field with the ends brought out as F1 and F2 leads. The second identical section would come out as F3 and F4 leads. At 360V, the coils would be wired in series so the F2 and F3 leads are tied together and the external field circuit goes on F1 and F4. At 180V, the coils are wired in parallel with F1 and F3 tied together and to one of the supply leads. F2 and F4 are tied together with the other supply lead.

Of course, the drive has to be configured with the field power supply matching the voltage. If the field power supply is not configured to match the field wiring, lots of trouble and even motor damage can occur. This would be even more true if the drive only has a basic field supply without active field current regulation.

This is just a small insight into why an experienced DC drive tech is needed to make this system work properly. DC systems are not simple and involve more interaction between the motor and the drive than AC.

Even worse, if the wrong thing is done with the field, the motor can accellerate uncontrollably and explode its armature. You don't want to be in the same room with the motor when that happens! There will be pieces of the motor out in the front yard and parking lot!