Caterpillar Generator Data

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FaradayFF

Senior Member
Location
California
Greetings,

Does anyone know where I can find data sheets/specs on older CAT standby units? I got a unit in the field that was manufactured back in 2002, and I need some data on it. Need to know if it will accommodate a new motor - looking for Starting kVA rating of the genset.

Thanks,
EE
 
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FaradayFF

Senior Member
Location
California
masterinbama said:
Try this

Guide to Choosing Generator to Motor Size - National Pump & Energy

Guide to Choosing Generator to Motor Size Some Notes for Sizing Generators Too small a generator will cause voltage fluctuations ...
www.nationalpump.com.au www.nationalpump.com.au

Sent from my LML211BL using Tapatalk
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Thanks for the link. I think it is good for general duty motors that will accept ~ 30% voltage dip. For some special connected motor applications, we need to have more data on the generator.
 
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paulengr

Senior Member
CAT is generally not much help. The generator is painted yellow but the generators are generally speaking not made by them. They do engines. Your best bet is to talk to a motor shop. Guess who Cat sends their generators to in our area? Not Peoria! Can’t tell by just the name plate but you probably have a Katolite generator on a CAT engine,

What kind of starting? And what loads? Usually the way you figure this out is first you add up all the running loads. Then you add the starting kva of the largest motor. If you don’t want voltage dips use 5x FLA x voltage x 1.732 / 1000. We use 5 instead of 6 because we already counted 1xFLA in the running load. The trouble is that this is excessively conservative. If you are willing to accept some droop you can use a smaller multiplier but it depends on the size of the running load. Also if you use a soft start or VFD you can cut your starting load down to a much smaller number which is why many generator manufacturers recommend not using ATL started motors on generators. You can do it but the generator size tends to be much larger than the motor.
 
don_resqcapt19

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
If you have the details on all of the loads, the starting sequence and the genset model, CAT will provide you with the voltage drop and frequency drop caused by adding loads. At least the office that covers our area will do that. I also think they have free software that will also give you that information. They have done this for me a couple of times for existing generators.
 
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texie

Senior Member
Location
Fort Collins, Colorado
Occupation
Electrician, Contractor, Inspector
don_resqcapt19 said:
If you have the details on all of the loads, the starting sequence and the genset model, CAT will provide you with the voltage drop and frequency drop caused by adding loads. At least the office that covers our area will do that. I also think they have free software that will also give you that information. They have done this for me a couple of times for existing generators.
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That's been my experience as well. All the major genset manufacturers will do this for their machines. Usually even older ones within reason.
I would add that it is import to use the the actual manufacturer's software as there are a lot of variables for a given size among manufacturers.
 
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paulengr

Senior Member
FaradayFF said:
Soft start may be a viable solution. Would need to make sure we're giving enough torque to the pump to bring the motor up to speed..
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If it’s a centrifugal pump no problem. Soft starts reduce torque but since torque is proportional to speed squared (pump affinity law) its never an issue. That’s the ideal application for one. You can ramp start or current limit start easily down to 150% of FLA as long as inertia isn’t excessive.

If it’s a positive displacement pump be careful. You can use a soft start but only mildly. I usually end up tuning them for around 300-500% of FLA using current limited starting.
 
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