Prime Generator shut down at 110% load

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Sajid khan

Sajid khan

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Location
Pakistan
Hi,
We recently had invited by our vendor for the load testing of generator. The generator is 150kVA prime rated tested on load bank with unity power factor. The load test was going fine from no load to 100% load. We asked to test genset on 110% load i.e at 132kw. Since the generator is of prime rating it should withstand 110% load for one hour by the definition of prime rated generator set but, the generator get shut down due to temperature rise(107C) goes beyond temperature limit(96C).
The arrangement of generator was such that the load bank was placed near to the alternator side.
The technical team of the vendor give the justification for generator shutdown is due to hot air released by load bank sucked by alternator into the generator canopy causing temperature to rise beyond the threshold limit.

Is this the correct justification??

Is there any possibility of temperature rise due to unity power factor load bank??



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This is one reason why it is not unusual for larger alternators to have temperature measurement on the cooling air on both the inlet and outlet.

Now that you know that the thing tripped on high temperature, I would start doing some closer investigation as to just what ambient temperature it can operate at.
 
petersonra said:
This is one reason why it is not unusual for larger alternators to have temperature measurement on the cooling air on both the inlet and outlet.

Now that you know that the thing tripped on high temperature, I would start doing some closer investigation as to just what ambient temperature it can operate at.
Click to expand...

The maximum allowable ambient temperature as specified by manufacturer is 45C


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It should be readily apparent from the physical arrangement of the equipment if the vendor's argument is tenable. I'd suggest a simple digital recording thermometer be placed at the cooling air inlet and then re-run the test.
 
Sajid khan said:
The arrangement of generator was such that the load bank was placed near to the alternator side.
Click to expand...
Shouldn't the vendor, who presumably arranged the tests, know that the proximity of the load could result in such an outcome?
Sounds fishy to me.

I would ask the vendor to revise the physical arrangement such that heat from the load bank was distance from the alternator. If he can't, I would decline the sale on the basis that it does not meet the claimed specification.
 
Besoeker3 said:
Shouldn't the vendor, who presumably arranged the tests, know that the proximity of the load could result in such an outcome?
Sounds fishy to me.

I would ask the vendor to revise the physical arrangement such that heat from the load bank was distance from the alternator. If he can't, I would decline the sale on the basis that it does not meet the claimed specification.
Click to expand...

I'd be surprised if the vendor was responsible for the equipment layout at the customer's site, unless hired for that purpose. They might even have a warning in their installation manual about having the cooling air intake too close to heat sources.
 
gadfly56 said:
I'd be surprised if the vendor was responsible for the equipment layout at the customer's site, unless hired for that purpose. They might even have a warning in their installation manual about having the cooling air intake too close to heat sources.
Click to expand...

True, but the vendor should know his equipment enough to bring this possibility to light BEFORE the test starts.
 
Besoeker3 said:
Shouldn't the vendor, who presumably arranged the tests, know that the proximity of the load could result in such an outcome?
Sounds fishy to me.

I would ask the vendor to revise the physical arrangement such that heat from the load bank was distance from the alternator. If he can't, I would decline the sale on the basis that it does not meet the claimed specification.
Click to expand...

I'd be surprised if the vendor was responsible for the equipment layout at the customer's site, unless hired for that purpose. They might even have a warning in their installation manual about having the cooling air intake too close to heat sources.
 
Sajid -
I'm guessing this is a Factory Acceptance Test - at the factory/vendor.
The gen did not pass.

As gens go, this one is not that big. Cables are not so large the Load bank can't be located away from the gen. Suggest to add required instrumentation, relocate the loadbank, rerun the test.

The mfg/vendor has to meet spec.


Add one thing. What does the spec sheet say? Does it acknowledge the prime ratings? The gen has to meet spec. But only what is in the contract.
 
petersonra said:
This is one reason why it is not unusual for larger alternators to have temperature measurement on the cooling air on both the inlet and outlet.

Now that you know that the thing tripped on high temperature, I would start doing some closer investigation as to just what ambient temperature it can operate at.
Click to expand...

The ambient temperature as specified by the manufacturer is 45C.


Sent from my iPhone using Tapatalk
 
petersonra said:
This is one reason why it is not unusual for larger alternators to have temperature measurement on the cooling air on both the inlet and outlet.

Now that you know that the thing tripped on high temperature, I would start doing some closer investigation as to just what ambient temperature it can operate at.
Click to expand...

The ambient temperature as specified by the manufacturer is 45C.


Sent from my iPhone using Tapatalk
 
petersonra said:
This is one reason why it is not unusual for larger alternators to have temperature measurement on the cooling air on both the inlet and outlet.

Now that you know that the thing tripped on high temperature, I would start doing some closer investigation as to just what ambient temperature it can operate at.
Click to expand...

The ambient temperature as specified by the manufacturer is 45C.


Sent from my iPhone using Tapatalk
 
iceworm said:
Sajid -
I'm guessing this is a Factory Acceptance Test - at the factory/vendor.
The gen did not pass.

As gens go, this one is not that big. Cables are not so large the Load bank can't be located away from the gen. Suggest to add required instrumentation, relocate the loadbank, rerun the test.

The mfg/vendor has to meet spec.


Add one thing. What does the spec sheet say? Does it acknowledge the prime ratings? The gen has to meet spec. But only what is in the contract.
Click to expand...

Yes the specs says a prime rated genset.
I Checked the name plate and manufacturer specs sheet, its the same prime rated genset.


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gadfly56 said:
I'd be surprised if the vendor was responsible for the equipment layout at the customer's site, unless hired for that purpose. They might even have a warning in their installation manual about having the cooling air intake too close to heat sources.
Click to expand...

If the customer was invited by the vendor, I would have expected the tests to have been done at the vendor's site.
 
Besoeker3 said:
If the customer was invited by the vendor, I would have expected the tests to have been done at the vendor's site.
Click to expand...

If it's a demo/test at the vendor's site, most vendors will run the test before the customer arrives to make sure it works! Although they might not have tested the 110% load.
 
PaulMmn said:
If it's a demo/test at the vendor's site, most vendors will run the test before the customer arrives to make sure it works! Although they might not have tested the 110% load.
Click to expand...

Yes exactly they did-not test on 110% load.


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