Black start Generator Versus Emergency Generator
Black start Generator Versus Emergency Generator
(OP)
Hi all
In general, In a power plant (capacity 100 MW to 4000 MW) the following equipment exists. Here power plants are Gas based or coal based.
Emergency Diesel Generator and Black start Diesel Generator.
Now I would like to know Why can not we club together and install a Black start diesel generator (In general larger capacity than Emergency Diesel Generator)?
Assume, Black start diesel generator will be operated as both purpose (Emergency and Black start).
Please provide any theoritical knowledge or Articles or our discussion forum thread.
Thank you
In general, In a power plant (capacity 100 MW to 4000 MW) the following equipment exists. Here power plants are Gas based or coal based.
Emergency Diesel Generator and Black start Diesel Generator.
Now I would like to know Why can not we club together and install a Black start diesel generator (In general larger capacity than Emergency Diesel Generator)?
Assume, Black start diesel generator will be operated as both purpose (Emergency and Black start).
Please provide any theoritical knowledge or Articles or our discussion forum thread.
Thank you






RE: Black start Generator Versus Emergency Generator
RE: Black start Generator Versus Emergency Generator
As LSpark points out, there are economic considerations that may work against combining these functions. One may not want to be committed to running a machine sized for black start any time EP (emergency power) is required. In addition, a higher reliability requirement (including maintenance costs) for an EP source might make the combined option even more expensive.
RE: Black start Generator Versus Emergency Generator
NFPA 70 and the NEC are two of several codes that I think could be settting restrictions based on emergency requirements.
Also as a side note, if the black start units have to run emergency load for an extended period of time, which I would think load wise of it being much, much less than what is needed for a cold start, the issue of running the gensets underloaded comes up. A 2,000kw genset running only 100kw of load for hours is killer on the engine.
RE: Black start Generator Versus Emergency Generator
But federal regulations in the US (specifically NERC) specify that a "black start generator" can supply power to the grid. In a roundabout way, this means that if I have a "black start generator" my transmission authority can call me up and tell me to start it and supply power to the grid. The diesel generator at my power plant is an "emergency" generator because it will only supply power to the local site. It may be "black start capable" but it is not a "black start generator" and I don't want it to be.
RE: Black start Generator Versus Emergency Generator
emergency genset could mean couple of things like quick response to a grid failure to put power back to the grid or use to recover frequency when one main generator fail and u need to maintain the cycle .
RE: Black start Generator Versus Emergency Generator
Large gas turbine plants typically need much more power to start than is feasible with a battery bank. These plants often use grid power to start up.
A plant with black start capability will have an onsite generator to supply start-up power. This may be a diesel set, or an aero derivative turbine.
In a large plant the power needed for a black start may be many times the power needed for emergency services.
There may be plants where the difference in capacity may not be that great, but regulations will generally demand that the set be capable of supplying emergency power as well as black start power simultaneously, so you are still looking at the sum of emergency power plus black start power. That's a lot of excess capacity that regulations may require to be run every month.
Bill
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"Why not the best?"
Jimmy Carter
RE: Black start Generator Versus Emergency Generator
There might be another reason as well. The BS genset likely feeds into the HV switchgear so you couldn't shut down the plant and do any HV swithgear maintenance or repairs if EP requires the BS/EP genset running which energizes the HV switchgear.
RE: Black start Generator Versus Emergency Generator
RE: Black start Generator Versus Emergency Generator
1. Governors/exciters responsive to load variations,
2. Nearby loads sufficient in size and number of blocks to allow operation within the safe turn-down limits of the prime mover,
3. Breakers & relays at a remote substation capable of synchronizing islands.