TYPES OF GENERATORS

The difference is basically in the name.

The two (2) main descriptions of generators are as follows: -

1) Main or Prime Generators are the Main or Primary source of power for the particular site.

2) Stand-By or Emergency generators are for when either the Main or Primary generator or Grid feed fail. These then start up and support the load.

In a multi-generator setup the first Generator may also be referred to as the Main or Primary generator as all the others are syncronised to it to parrallel them for large loads.

Having said all that, a Generator will quite often have two (2) ratings: Prime and Standby.

The Prime rating will usually be slightly less than the Stand-by rating as a generator running as Prime is designed to run 24*7*365 with minimal down-time for Maintenance, where as a Stand-By or Emergency Generator is expected to be sitting idle for 90% or more of its life but support a large proportion of its rated load on one hit very quickly.

Hope this helps,

Regards,
Sapper

thanks

Well said.I would only add that prime and standby ratings are due to prime movers ability.Like Diesel engine for continuous (Main /Prime) will be rated low as compared to stand by .

Caterpillar has three ratings namely...,

Standby

Prime

Continuous

The loading characterstics ( Load factor) is what decides the generator you need/specify.

There is an elaborate definition of load factor on CAT's website which you can refer.

Cheers.