Generator Sizing
Generator Sizing
(OP)
As a part of a project I am working on I have to size a generator.
The generator will be used as a standby power source, used only when utility goes down.
The primary function of this generator is to power a mine hoist to get men out of a mine. Secondary functions include dewatering pumps, site heaters, site emergency lights, comms, and various other minor loads.
The hoist motor is synchronous and currently sized at 5.5MW (7000hp) and when power is down the hoist will be run at half speed, the reason for doing this as I understand is to reduce the size of the required generator. The hoist motor is controlled via a ABB ACS6000 drive or equivalent.
My plan on sizing this generator;
- ensure that hoist operates in the capability curve of the generator
- ensure that generator is stable for the entire hoisting cycle
- If generator is within the capability curve and stable for entire hoisting cycle all other loads should have no issues - my thought on this one is the generator will have to be oversized for the hoist and the other loads will fit within this oversized portion.
Does this look correct?
Is there anything else I should be looking at?
Does anyone know of a good paper or other sources of information on sizing of generators for applications similar to this?
Thanks
The generator will be used as a standby power source, used only when utility goes down.
The primary function of this generator is to power a mine hoist to get men out of a mine. Secondary functions include dewatering pumps, site heaters, site emergency lights, comms, and various other minor loads.
The hoist motor is synchronous and currently sized at 5.5MW (7000hp) and when power is down the hoist will be run at half speed, the reason for doing this as I understand is to reduce the size of the required generator. The hoist motor is controlled via a ABB ACS6000 drive or equivalent.
My plan on sizing this generator;
- ensure that hoist operates in the capability curve of the generator
- ensure that generator is stable for the entire hoisting cycle
- If generator is within the capability curve and stable for entire hoisting cycle all other loads should have no issues - my thought on this one is the generator will have to be oversized for the hoist and the other loads will fit within this oversized portion.
Does this look correct?
Is there anything else I should be looking at?
Does anyone know of a good paper or other sources of information on sizing of generators for applications similar to this?
Thanks





RE: Generator Sizing
My view is that it does not cost that much more to invest in a larger generator and have some margin. I would not skimp on generator sizing. Especially if availability of the hoist can keep the business running (revenue) during an outage.
Rafiq Bulsara
http://www.srengineersct.com
RE: Generator Sizing
You better ask a professional consultant to do the planning.
Regards
Wolf
RE: Generator Sizing
Rafiq Bulsara
http://www.srengineersct.com
RE: Generator Sizing
The Client does not plan on operating on standby power, only to get the men out of the mine, therefore no revenue.
I am employed by the consulting firm, and yes I will have to get someone involved who knows more then me on generator sizing, we have the experts within the company, but by passing it off completly I will never better myself, hence the reason for looking into this.
If more specifics are required let me know and I will provide more,
Thanks again
RE: Generator Sizing
Rafiq Bulsara
http://www.srengineersct.com
RE: Generator Sizing
To OP - This is mainly a trouble shooting forum for engineers with real work related problems, not a free on-line consultancy service.
Muthu
www.edison.co.in
RE: Generator Sizing
RE: Generator Sizing
- Governor loop performance. Most big drives have a fairly tight tolerance on the acceptable supply frequency range.
- Synchronous drives can normally regenerate into the source. Engines hate being driven as compressors.
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RE: Generator Sizing
RE: Generator Sizing
RE: Generator Sizing
I agree, the more I look into this problem the less I see sizing the generator as an issue.
For sizing I am going to plot the capability curve of the generator and compair it to the power locus of the hoist.
I think the problem I am going to run into is going to be the stability of the generator. I have been told that a rule of thumb for generator step loading is about 40% of the generator load.
If this is the case the generator would have to be oversized to remain stable when the hoist is started. Something I will have to investigate to educate myself.