Continuous, Standby, Emergency

They are asking you to rate the load capacity as if it was a continuous load.

Emergency rating are 100% of the load.

Continuous about 60 to 70 % of the load.

http://tawinc.com/LinkClick.aspx?fileticket=M6nn0PMbUp0%3D&tabid=137

The International Standards Organization (ISO) ISO 8528-1 (2005) defines three types of duty:

· Continuous Operating Power (COP)

· Prime Running Power (PRP)

· Limited-Time running Power (LTP)

Continuous Operating Power (COP): Continuous operating power is the power a generator set can operate at a continuous load for an unlimited number of hours under stated ambient conditions. Maintenance according to the manufacturer must be followed to reach these standards.

Prime Running Power (PRP): Prime running power is the maximum power a generator set has during a variable power sequence for an unlimited number of hours under stated ambient conditions. Maintenance according to the manufacturer must be followed to reach these standards.

Limited-Time Running Power (LTP): Limited-time running power is the maximum power that a generator set delivers for up to 500 hours per year

under stated ambient conditions. Only 300 hours can be continuous running. Maintenance according to the manufacturer must be followed to reach these standards.

In limited time rating(500hrs) what is the maximum number of hrs it can run at a stretch without stopping say during a power failure as standby or emergency source ?. Also definition of "standby rating" is not given. There should be definitions of these terms from BS,IEC,VDE,NEC,NEMA etc. Are they different from each other?.

In the U.S. NEC (National Electrical Code), I think "continuous" includes anything over three hours. It would not be rare for a power outage to last that long.

Guys, Understand with your respond. The interesting question is why continuous rating became popular for emergency generator while in operation circumtance it will be standby mode. Why most of end user like it to using generator with continuous rating rather than standby or emergency rating?? Is it about price?? Common Practices?? Even in orange book IEEE actually, it recommended to using continuous rating. Anyway, we should be not to mixed-up terminology for power generation and load classification (continuous/intermittent/standby or spare load). There are some advantage and disadvantage that offering from here but final decission is actually based on project specification and engineering wise. For me it is not about right or wrong but is about Company preferences. Just curious if any reason that may cover my understanding.

Forget all about this; you have no understanding at all.

How far did you think you know in analysis..

???

You seem to be confused here.

There are a lot of different 'kinds" of generator.

There are 3 ratings (I reckon there are 2, prime and standby) of generator based on duty cycle

The same generator can have different ratings and you select according to your load and duty cycle.

"Emergency" generator is a functional descriptor.

I think your client wants a XkVA prime rating where X is your normal full load. Prime rating will also specify how long it can run at "overload",

Provide us with the exact info you have for your project and you might get more explanations and recommendations (you'd figure the generator merchant would do this for you.)

Gentlement,

Thanks for your responds. I might be not good enough to describe my understanding. Appreciated for Mr. Tornado that remind me about that.

I am agree with "electricalexperts65" about (ISO) 8528-1 (2005). Actually we can combine from any code, standard, or RP.

Further from this standard, in manufacturing side, in common practices, Generator sets (engine + alternator) are based on typical load factor, hours of use per year, peak demand and application use. That is why in market you will be find some rating such as "Standby Rating", "Prime Rating", and "Continuous Rating".

1.Standby Rating

-Output available with varying load for the duration of the interruption for the normal power source.

This is the definitions that make me open this thread or discussion. Let say in my case, I have normal generation that will be fed all load in facilities during normal condition. Once there are some conditions that make normal power not available, dead bus signal from normal switchboard will be sent to turn ON emergency diesel generator. Back to the previous discussion why it is required Continuous Ratings as per describe in No.3. whereas "standby rating" is good enough for this case?? Anyway forget it, I got some reason that reasonable actually.

-Typical Load Factor = 60% or less

-Typical Hours per Year = 500 hours

-Typical Peak Demand = 80% of standby rated

-ekW with 100% of rating available for the duration of an emergency outage.

-Typical Application = Building Services

-standby and enclosed/sheltered environment.

2. Prime Rating

- Output available with varying load for an unlimited time.

-Typical Load Factor = 60% to 70%

-Typical Hours per Year = no limit

-Typical Peak Demand = 100% of prime rating used occasionally.

-Typical Application = industrial, cogeneration, etc.

3. Continuous Rating

- Output available without varying load for an Unlimited time.

- Typical Load Factor = 70% to 100%

- Typical Hours per Year = no limit

- Typical Peak Demand = 100% of continuous

- rating used 100% of the time.

-Typical Application = base load, utility, cogeneration, parallel operation.

-Operating above these rating definitions will

When we decided to purchase generator we need to keep in mind if operating above the rating definitions will result in shorter life, higher generating costs per year, result in shorter life, and higher generating costs. But we need to also consider that generator normal operating load should not be less than 50% otherwise it will be decrease reliability due to carbon buildup in engine.

If only text book, we can find actually in many code, standard, handbook, recommended practices, and now became popular in on-line simulation or training.

Well, I hope we are clear now. Thanks for all input. Cheers.