200 hp motor fail without overload really trip.

BITI BISHARA

Member
Join Date
Jul 2019
Location
BRAHMAN
Posts
41
Hello guys,
200 hp air compressure motor winding fail but over load really was not trip.Motor rated current 288 amps and over load setting is 180 amps. Motor control circuit is star delta.
My question is why over load did not trip. Please can you suggest me and what type of over load really I should use.
Over load really was Allen Bradley brand.
Kind regards.
Biti
 
Was the Overload Relay properly located in the circuit, both the power circuit and the control circuit? My first suspicion is that it was not.

What type of overload relay? Electronic or Electro Mechanical?

Did you have a phase lose event or a severe phase imbalance?

We really need more information, as much as you can gather. Otherwise it’s a game of 20 Questions.
 
We really need more information, as much as you can gather. Otherwise it’s a game of 20 Questions.

Along with jraefs questions I have a few more.

1. Starts per hour.
2. You list the power as HP and your location suggests you might have 50hz 400 V power available, and might be using star delta starting. Can you answer the type of power, type of starting, and if equipment is hp or kw rated?
3. The OL setting of 180 and motor rating of 288 is a large discrepancy, can you explain why?
 
The winding may fail for other reasons, not just due to overload, maybe water has entered the motor, or it is installed in a very hot place, or a mechanical problem has overheated the motor or the air circulation was clogged.
 
The winding may fail for other reasons, not just due to overload,

ife's post reminded myself of another strange troubleshoot I was part of:

The original motor had bearing problems , the rotor dragged across the stator and "welded/smeared the laminations creating hotspots the cooling system was never designed to dissipate. In this instance the motor rewinder never corrected the lamination "smearing" and the motor was running at about 80% of full load but the surface temperature of the motor was 360 degrees fahenheit.

Is this a new motor or rewound?

An internal inspection of the motor is needed.
 
Last edited:
Was the Overload Relay properly located in the circuit, both the power circuit and the control circuit? My first suspicion is that it was not.

What type of overload relay? Electronic or Electro-Mechanical?

Did you have a phase lose event or a severe phase imbalance?

We really need more information, as much as you can gather. Otherwise it’s a game of 20 Questions.

THANKS,
yes, overload realy was there.Both power circuit and control circuits.
Electro mechanical ol realy.
i dont check phase lose but i found phase to phase power 385-387-389
Regards.
biti
 
Along with jraefs questions I have a few more.

1. Starts per hour.
2. You list the power as HP and your location suggests you might have 50hz 400 V power available, and might be using star delta starting. Can you answer the type of power, type of starting, and if equipment is hp or kw rated?
3. The OL setting of 180 and motor rating of 288 is a large discrepancy, can you explain why?

it is an ingersoll rand compressor motor and running with load maximum time.
power is hp 200,hz 60,voltage 380,star delta control.
motor rated current 288 and main contactor after use ol realy and current setting is 180 amps.
we purchase the compressor from ingersoll rand company and we maintain electrical circuits diagram as same as original.
 
The winding may fail for other reasons, not just due to overload, maybe water has entered the motor, or it is installed in a very hot place, or a mechanical problem has overheated the motor or the air circulation was clogged.

yes, it is installed very hot place and the outside temperature is always 30 to 40-degree centigrade. Motor all side close by the cover.
There was no mechanical or bearing problem. motor found very free.
 
You say that it is Star/Delta started, so I am assuming that the overload is seeing Phase current rather than Line. In which case the overload should be set at 0.58 * Line current, or 167 Amps. Another way of doing the same calculation is Line current divided by 1.732, 1.732 being the square root of 3.

A thermal overload is very much a compromise. It is trying to simulate the heating in a standard motor, and it will never be right. On smaller, cheaper motors it is a compromise worth accepting, but for larger motors I would always try to get one with temperature sensors built in to the windings. That way you have a true temperature rather than a simulated one and you can react with greater accuracy. Compressors are generally sold on price and so have the cheapest methods available, thermal overloads are cheap.
 
ife's post reminded myself of another strange troubleshoot I was part of:

The original motor had bearing problems , the rotor dragged across the stator and "welded/smeared the laminations creating hotspots the cooling system was never designed to dissipate. In this instance the motor rewinder never corrected the lamination "smearing" and the motor was running at about 80% of full load but the surface temperature of the motor was 360 degrees fahenheit.

Is this a new motor or rewound?

An internal inspection of the motor is needed.

yes,compressor installed after with in oneyear motor fail and we make it rewinding.it was 3 years before and now again fail.motor grounded,short circiits coil to coil.
 
THANKS,
yes, overload realy was there.Both power circuit and control circuits.
Electro mechanical ol realy.
i dont check phase lose but i found phase to phase power 385-387-389
Regards.
biti
I'm not trying to be picky, just correct, because I'm suspecting Ingersol Rand of a possible marketing trick, hype or miss direction.

Is it possible that you mean voltage? or do you mean amps measured on the line?

it is an ingersoll rand compressor motor and running with load maximum time.

Again, not trying to be picky just trying to get to the root cause of the problem. Are you saying " It's an Ingersol Rand compressor motor and it's running at maximum load all of the time?

power is hp 200,hz 60,voltage 380,star delta control.

I'm not sure it's part of the problem, but the 60 hz thing bothers me. I thought 50 hz was standard with that voltage.

motor rated current 288 and main contactor after use ol realy and current setting is 180 amps.

I think BryanG has it correct and Ingersol Rand is guilty of running the compressor in the service factor zone

You say that it is Star/Delta started, so I am assuming that the overload is seeing Phase current rather than Line. In which case the overload should be set at 0.58 * Line current, or 167 Amps. Another way of doing the same calculation is Line current divided by 1.732, 1.732 being the square root of 3.

yes, it is installed very hot place and the outside temperature is always 30 to 40-degree centigrade. Motor all side close by the cover.
There was no mechanical or bearing problem. motor found very free.

I cannot see where you indicated exactly what type of overloads. Are they eutectic alloy, bimetal or electronic?

If I'm right that you are running at maximum load most of the time and Ingersol Rand has loaded the motor in the service factor area, then placing eutectic alloy or bimetal overloads in the same temperature as the motor would be one step closer to protecting the motor.

If they are electronic it won't make any difference.

yes,compressor installed after with in oneyear motor fail and we make it rewinding.it was 3 years before and now again fail.motor grounded,short circiits coil to coil.

Not sure how Ingersol Rand is loading your compressors, but where I work we have 6 Ingersol Rand Centac compressors 700 hp each (yes I know it's an insane amount of air). The Centac's use a 4 to 20 current input from a motor current tranducer to limit the motor loading. If you have the same then you can limit the motor loading to give you more motor life.
 
In a delta-star motor connection, for each of the 6 cables that arrive the motor circulates the nominal current of the motor divided by the square root of 3 and at this value the thermal protection must be regulated, not to the current the motor plate says

288A / 1.73 = 166A

That thermal protection was regulated too high.
 
In a delta-star motor connection, for each of the 6 cables that arrive the motor circulates the nominal current of the motor divided by the square root of 3 and at this value the thermal protection must be regulated, not to the current the motor plate says

288A / 1.73 = 166A

That thermal protection was regulated too high.
Dear lfe,
Thanks for lesson.
If I use star delta connection then I should apply your formula motor rated current diveded by 1.732 and this value set as overload current.
Now my question is if I use small motor 1.5 kw star connection. This time how do I calculate the overload setting current. Please let me know the formula.
Kind regards.
Biti.
 
Hello all,
I send the motor for rewinding and waiting for fix back and run the compressure.
I will set the overload realy at 167 amps and it will be observation.
Motor have thermostat but since before it was not using. Can I use this thermostat by fixing one additional realy.
Kindly guide and support me to increase our motor life.
Kind regards.
Biti.
 

Similar Topics

Hello Dear Experts Is anyone knows where i can find some example to make some positionning function with S7-1200 Motion Control (v7.0) functions...
Replies
0
Views
446
Hello all, I'm working with an s7-1200 and a stepper motor in Tia portal v17. This stepper motor is an SMD23E2 and I am attempting to connect...
Replies
19
Views
2,799
Hello all, I'm working on a project involving stepper motors that is currently utilizing Allen Bradley hardware/software, but I'm transitioning...
Replies
12
Views
3,056
I had planned to use PTO instructions to control a servo motor, single axis only. We have a ML1200 BWA model. According to the ML1200 manual...
Replies
7
Views
3,441
Hello specialists! I am facing the problem with controlling the stepper motor. In this project I am using S7-1200 CPU 1214C DC/DC/DC (4 PTO...
Replies
8
Views
3,703
Back
Top Bottom