Pic - 100HP Motor Failure

[Sierrasparky]

A Weeble Motor. "Weebles wobble but they don't burn up!"

Yea! well this one did.:roll:

 

[zog]

Lack of maintenance.

Sure a lack of maintenance was a factor, but a simple proper setting of the OCCP would have prevented this costly failure. Sometimes I wonder why poeple bother using OCPD's, just to meet code maybe, but if not sized properly they are useless. In my experience many people don't understand the concept.

 

[LarryFine]

Don't discourage your fans. After all, imitation is the sincerest form of flattery. :grin:

Touch?!

 

[eric9822]

I asked about the OCPD's and was assured they were correct. I will be checking on Monday. :roll:

 

[neutral]

I asked about the OCPD's and was assured they were correct. I will be checking on Monday. :roll:

Did you mean motor overloads should have protected the motor? Who in their right mind would run a 100 hp motor using a fuse or breaker for motor protection?

 

[frenchelectrican]

Did you mean motor overloads should have protected the motor? Who in their right mind would run a 100 hp motor using a fuse or breaker for motor protection?

I have see them used for back up only if the standard OL system fail the fuse or breaker should be a back up source but not always the case depending on how you set up system is especally with multi motor set up that will compound it.

Merci,Marc

 

[quogueelectric]

Did you mean motor overloads should have protected the motor? Who in their right mind would run a 100 hp motor using a fuse or breaker for motor protection?

An untrained person or persons.

 

[frenchelectrican]

An untrained person or persons.

Now that is the other matter with untrained or non qualifed dolts they will find a way to oversize the fuse or find a way to increase size of the breaker way above what the NEC called for.

With proper sized fuse or breaker it will serve as back up in case the O/L failure { it happend once a while like that }

Merci,Marc

 

[quogueelectric]

Now that is the other matter with untrained or non qualifed dolts they will find a way to oversize the fuse or find a way to increase size of the breaker way above what the NEC called for.

With proper sized fuse or breaker it will serve as back up in case the O/L failure { it happend once a while like that }

Merci,Marc

Very few electricians understand exactly what it is the o/l s do. Sad but true.

 

[quogueelectric]

I have see them used for back up only if the standard OL system fail the fuse or breaker should be a back up source but not always the case depending on how you set up system is especally with multi motor set up that will compound it.

Merci,Marc

I have commonly see incompetent persons install the wrong ols. It doesnt phase me anymore. When you are done horsing around with the untrained and have done enough damage I will come in and fix it but it wont be cheap. Many motor driven loads never reach max output so many bad installs get a free ride just by dumb luck.

 

[eric9822]

Did you mean motor overloads should have protected the motor? Who in their right mind would run a 100 hp motor using a fuse or breaker for motor protection?

The motor was protected by fuses and thermal overloads. I have no idea if they were sized correctly, my guess is they were not. I will be checking on Monday. When I saw the motor I could not believe what I was seeing.

 

[Besoeker]

To me it looks like a case of the OCPD set improperly. If set right you should never get motor damage. I bet the breaker tripped at some point from the increased current drawn by the increased friction of the bearings drying out and the electician just turned up the trip setting allowing for the motor to run to failure. Classic case of improper device settings and/or unqualified personel adjusting OCPD's.

I don't think you can necessarily infer that.

 

[ptonsparky]

Pretty sure the electrician and an amp meter weren't included when these belts were tightened up.

 

[iwire]

To me it looks like a case of the OCPD set improperly. If set right you should never get motor damage. I bet the breaker tripped at some point from the increased current drawn by the increased friction of the bearings drying out and the electrician just turned up the trip setting allowing for the motor to run to failure. Classic case of improper device settings and/or unqualified personnel adjusting OCPD's.

I think your asking a lot of the motor OCPDs and just trying to throw stones at at the installer here.

To work like your suggesting the motor would have to be running nearly fully loaded normally to be able for the OCPDs to 'notice' the increased friction of a dry bearing.

Most times motors are not running fully loaded so the increased friction of the bearing would go unnoticed.

I will go with side loading forces (over tightened belts) beyond design capacity.

 

[TwinCitySparky]

Boy you'd think somone would have noticed the smoke before she blew!

Or sounds or the decreased/stopped production output. That thing had to be making some really wild noises to get to that point.

The paint is cooked off around the shaft. They must only have heat detectors for fire detection.

 

[Besoeker]

Pretty sure the electrician and an amp meter weren't included when these belts were tightened up.

Overtightening the belts might not reflect very much in the motor current. You aren't asking the motor to produce more torque. The torque is proportional to the difference between the two sides of the belt rather than their absolute values so you could over tension the belt to an extent that would be detrimental to bearing life without overloading the motor.

 

[Sierrasparky]

Overtightening the belts might not reflect very much in the motor current. You aren't asking the motor to produce more torque. The torque is proportional to the difference between the two sides of the belt rather than their absolute values so you could over tension the belt to an extent that would be detrimental to bearing life without overloading the motor.

Yea the extra side loading of the bearing proabably would not show enough increase for an installer to notice.
Hey Tight is always better right!

 

[zog]

I think your asking a lot of the motor OCPDs and just trying to throw stones at at the installer here.

Not necessarily the installer, more likely the operator that replaced the proper OCPD with a larger one when the motor tripped off line, seen it many times.

To work like your suggesting the motor would have to be running nearly fully loaded normally to be able for the OCPDs to 'notice' the increased friction of a dry bearing.

Most times motors are not running fully loaded so the increased friction of the bearing would go unnoticed.

Good point, but proper sizing of OCPD's/settings should be selected with the motor damage curves in mind. Again, maybe I am too used to larger equipment where some actual engineering is done.

 

[K8MHZ]

The shaft may have developed a crack and broken.

The pics don't really show any sign of overheating to the point of causing such a catastrophic failure.

The load may have been imbalanced causing the shaft to vibrate and poor manufacture may have led to a crack.

 

[frenchelectrican]

I just wondering why not if someone knew it will have very hevey load on the motor shaft why not make a extendison shaft and also add a bearing block on one side to really reduce the amount of side loading on the shaft.

I done that way couple time I know it not easy to do it but with that many belt and pretty high speed { 3600T/min } I think my option that will justify with very hevey or high shock loads using a bearing block set up.

Merci,Marc


* T/min = RPM { turn per min the same as rev per min }