# Urgent, soft start trouble need help



## JayH (Nov 13, 2009)

Sounds like a dead short somewhere, but it would be impossible to diagnose with this limited information.


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## drsparky (Nov 13, 2008)

I agree with Jay check for faults, "it was working before" means very little.


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## RIVETER (Sep 26, 2009)

Are you saying that the motor burned or the soft start...or both? What did you mean by saying you engaged the stop?


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## varmit (Apr 19, 2009)

It is hard to say from the limited info, but I would guess either a closed bypass contactor during start or a shorted SCR.

I have seen several drives and soft starts fail after setting idle for long periods of time.

Suggestions: Meg motors before powering up. Check SCRs for shorts - use multimeter with diode function. After other tests check OK, if bypass contactor is accessible, disconnect bypass contactor power leads, disconnect motor from soft start, connect a volt and /or frequency meter to soft start power output. Initiate a start. The output voltage and frequency should be very close on all phase combinations.

Other questions: How long had this equipment ran before setting idle? Has there been any changes to the power system? What is the environmental conditions of the motor and controller locations?


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## John Valdes (May 17, 2007)

How do you know the motor shorted and what blew up? The motor or the control?
There should have been no output to the motor unless you somehow closed the run input on the control or the bypass (If you have one) was closed. So be a little more specific as to what exactly happened.

Disconnect the motors from the soft starts (at the control) and energize the circuit. Make sure the soft start powers up with no error codes. You might get something due to the motor being disconnected. If you have a bypass make sure it is working properly. Check for correct voltage.

Megger the motors and conductors from the soft start.

If all checks out, you should be able to reconnect the motors and start them up too.

If it was the drive that blew up, it most likely was the input bridge. Sometimes when caps sit for awhile they will dry out and let the smoke out too.

Edit. Sorry, disregard disconnecting the motors from the controls. I did not realize the motors were 200hp.


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## Hammer70 (Feb 26, 2010)

*Clarification*

Once again it was the 200hp motor that blew up. the controls (on a seperate low voltage circuit) were set to the off position. the emergency stop was engauged... meaning open circuit, off, disconnected, dead... visualy, on the exterior, the soft start is in perfect condition. the location is clean and dry, however it is cold about 34F. 
when I energized the circuit sparks flew out of the motor. again the soft start is visualy ok. I am not a technician. I pull wire and run branch circuits. but, i am the most qualified person on site to address this problem.
Varmit,
thank you i will check the diodes 
John,
I have already disconnected all of the motors from their respective soft starts. all of the soft starts and motors are of identical make and model. I was told that a few years ago the same thing happened all they did was replace the motor the soft start was ok. but i think the soft start is the culprit. everything was in the off position, so how did line voltage get passed the soft start. perhaps the bypass contactor or the scrs???
I connected a 1/3 hp motor to the soft start and recreated the situation in this case the motor did not react when the main disconnect was closed. i then went through the start up proceedure and everything checked out it worked properly. so I tested another soft start it too checked out. then i connected another 200hp motor to another soft start (one that i had tested with the 1/3hp motor). to my surprise the 200hp motor blew up. the motor made no sound other than a pop. it did not grunt as if under load trying to start. it was as if somebody had stabbed a screwdriver into the windings and shorted them. but that doesnt explain how line voltage got passed the soft start if the controls are in the off position. now i have lost two identical motors, to two identical soft starts, in the same location. 
input voltage is 488v on all phase combinations @ 60hz. there have been no significant chages made to the electrical supply. last year this motor ran for nearly 3 months without any problems under the same conditions and was shut down in the proper manner. ghost voltage is present at the load side of the starter. b phase on this soft start goes straight through the starter acts on a & c phases only. i have looked for information on the soft starter but i can find nothing helpful. please point me in the right direction. I can do this i am confident in that. I just need a little advice.

Hammer


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## varmit (Apr 19, 2009)

Hello,

You say that B phase goes "strait through" the soft start? This would be a problem, as on startup a soft start functions as a VFD for the few seconds of start ramp. If one phase is always "hot" through the soft start, to the motor, it could backfeed the drive output using the motor as a jumper. If a VFD is fed on the output side, things will go wrong. The small motor may not have had enough capacity to be enough of a "jumper" to replicate the problem on a 200 HP drive.

If this unit is showing full voltage on an output phase, with no run command, the soft start has a problem. Also, disconnect the motors from their starters and meg the motors. Never meg a motor with the motor connected to a drive.

Good luck.


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## John Valdes (May 17, 2007)

Sounds like you need some help from the vendor. I just responded to another post where the OP could most likely had his issue corrected last week, but for some reason will not call for help.

Call the motor shop you use and see if they can help you first. If they cannot help, THEY should get Siemens involved.

A good vendor with the right people will help with issues like this at no charge. A good motor shop would be in there with you. They are rewinding the two blown up motors right? Of course they want the repair work, but helping a customer brings much more work down the road. If they will not help find a new vendor.

Since you have blown up two motors on the same soft start, would you not think the next step would be to replace the control? I do.

One more thing. Can you use the bypass to make sure the motor is good? Try that too.


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## Rockyd (Apr 22, 2007)

Hammer is too proud to talk to a vendor from what I gather from his nasty email. Guess some people like to make their own problems.


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## John Valdes (May 17, 2007)

Rockyd said:


> Hammer is too proud to talk to a vendor from what I gather from his nasty email. Guess some people like to make their own problems.


I used to think if I called someone for help it made me look less qualified. Most young technicians are concerned they will look unqualified if they reach out for help. As we get older, hopefully we get smarter and use every tool available to us. Sometimes a phone is the best tool for the job.

I once was working on a break down for several hours when the plant manager walked up and asked me if I called the vendor? After spending a few minutes on the phone with the vendor (tech support) the problem was resolved and I learned two very valuable lessons. 
1) I learned how to fix that particular issue on that particular machine. 
2) I learned that there were actually people that get paid to assist their customers. 
Number 2 has saved me, and my customers more hours and aggravation than I can can even imagine.

PS........Nasty email?


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## Hammer70 (Feb 26, 2010)

*Rockys whining*

John v,

Rocky was the first person to respond to my post. He did so in private, and it was like a solicitation. He gave the number of a vendor a contact person even gave me the street address in anchorage. Am I foolish or was that a solicitation. I have my own vendor resources, I have worked in a supply house before. What I know is that book knowledge counts little compared to field experience. Joining this forum I thought I would be tapping into a resource of field experience, since I have already contacted vendors. And, as I suspected the information from you and varmit have been more helpful than the vendor. rocky needs to get a life and let this go. he has been sending me private messages ever since i told him to buzz off two weeks ago.
Anyhow I went oldschool on this one temporarily. I used 3 contactors and a timer. I split the winding and ive got it down to 3 second delay. It works fine for now. at least it isnt blowing up motors.

Hammer


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## John Valdes (May 17, 2007)

Hammer70 said:


> John v,
> 
> Rocky was the first person to respond to my post. He did so in private, and it was like a solicitation. He gave the number of a vendor a contact person even gave me the street address in anchorage. Am I foolish or was that a solicitation. I have my own vendor resources, I have worked in a supply house before. What I know is that book knowledge counts little compared to field experience. Joining this forum I thought I would be tapping into a resource of field experience, since I have already contacted vendors. And, as I suspected the information from you and varmit have been more helpful than the vendor. rocky needs to get a life and let this go. he has been sending me private messages ever since i told him to buzz off two weeks ago.
> Anyhow I went oldschool on this one temporarily. I used 3 contactors and a timer. I split the winding and ive got it down to 3 second delay. It works fine for now. at least it isnt blowing up motors.
> ...


Hammer,
I did not mean to get involved with you and the other guy. It does sound like solicitation to me also. But I also know that my vendors are there for me when I want to throw my tools down and go home.
A good example is Baldor Electric. When I am troubleshooting their control and get stuck, I can call Ft. Smith and talk to at least one of their control guys. All of them came from the field. Thats why they are working there, solving problems. Hands on type guys. They have simulators for all their products and can run through most any issue in real time with you. They are my friends and they know their stuff. They are book people too. 

Good work getting up and running. I like the wye/delta start call! :thumbsup:


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## miller_elex (Jan 25, 2008)

Doesn't that soft start need to be programmed??

By programmed, I mean a factory programmed chip has to be installed.


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## miller_elex (Jan 25, 2008)

http://support.automation.siemens.c....csinfo&lang=en&objID=26256561&subtype=133300

Found the manual, for those who are curious.


There's one a few manuals down with a commissioning flow chart... didn't notice a bubble with 'if your motor spontaneously combusts, then do this...'


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## Rockyd (Apr 22, 2007)

> Rocky was the first person to respond to my post. He did so in private, and it was like a solicitation. He gave the number of a vendor a contact person even gave me the street address in anchorage.


Yes Hammer I did reply in private because you asked for help IN ALASKA. How many in this forum are from Alaska? I recommended Hayden Electric - because they specialize in motors and drives. I don't work there, have never worked there, but have recieved good service over the years. 



> Am I foolish or was that a solicitation.


Your a damn fool.



> I have worked in a supply house before. What I know is that book knowledge counts little compared to field experience.


So what if you worked in a supply house? The guys I referred you to have a shop locally in which they rewind, and fix motors and drives in Anchorage.

As far as experience, piss up a rope asshole. I have 30 years in the electrical field, but am not an expert on VFD's, so you got a reference to a shop that is qualified for such events.



> rocky needs to get a life and let this go.


Hey noob, you came here looking for help. I offered, and get a slap in the face. Sorry I wasted my time on an ungrateful dumb ass.


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## Electric_Light (Apr 6, 2010)

TWO HUNDRED horsepower? Must be one heck of an elevator.


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## ACDC (Apr 15, 2010)

Hammer70 said:


> Hello to all,
> I am new to this forum. I found it when researching a problem with soft starts. The article I was directed to was about soft starts and elevator applications. Though the information was very enlightening it did not cover my issue. I have very little knowledge of electronic soft starts. But, I do believe that it is the culpret in this case.
> Here is what happened. After a nine month period I was putting some equipment back online. I made my preliminary checks. Everything checked ok, I know the equipment was in peak condition when shut down, and nothing had been changed during the shutdown. Satisfied that all is well I put the control in the stop position, for extra measure I engauged the emergency stop. Next, I energized the circuit. In an instant the motor shorted. I got the whole show, sparks smoke and a pop. $20k lost in an instant. What was missing was the sound of a motor under load straining to start, just pop and it was over. What happened???? I need to know soon because Ive got 2 more that I need up and running but I am afraid to test.
> LOCATION:
> ...


Hi, my guess is the motor(s) must have absorbed moisture during the standing period. It is good to always do an insulation test on a motor and cable before connecting it. The *most important* fact not addressed here is the main circuit protection for the soft starter. Consult the manual and it will indicate the size(A) and type of fuse/breaker. In case of a fault in future your SS and motor should be protected! Never assume that any installation was done correctly. The soft start could have been set up incorrectly and thus output max at start. The controls you "opened" could also not have been configured correctly.

Good luck!
Greetings


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## macbeton (Jun 7, 2017)

If a janitor is posing as an electrician - this thread happens.


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## The_Modifier (Oct 24, 2009)

macbeton said:


> If a janitor is posing as an electrician - this thread happens.


Agreed! A Latvian can't read that the original post is over 7 years old! Maybe get your eyes checked and possibly look into a night course to get out of that janitor job you keep bragging about all over the forum.:thumbsup:


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## macbeton (Jun 7, 2017)

The problem still exists, doesn't matter 7 or 17 years.


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## JRaef (Mar 23, 2009)

Huh... I must have been off the site for a while back then, I rarely miss a post about soft starters or drives.

For those who are curious, that Siemens soft starter that he had was a poor choice, that model is made to be cheap, not good, and it only has SCRs on two of the 3 phases. So his report of the circuit being continuous straight through Phase B is accurate, that's how those are MADE! It makes the motor start rough and create a lot of heat, so should never be used on anything other than a pump that will start once in a while and accelerate in 10 seconds or less. Any longer and you start to compromise the winding insulation. then if even ONE SCR shorts, there is inherently a full path through a motor winding and no way to stop it other than the main disconnect. So the E-Stop would have had no effect.

I know, it's a zombie thread, but I like to get that message out to people; the cheapest soft starters are NOT the best way to go in most cases.


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