load flow and motor starting studies
load flow and motor starting studies
(OP)
Guys,
I used to study load flow with normal voltage level for utility and define several scenarios in distribution level such as loosing an MCC etc.
I was looking at another study that has only 3 scenarios with 95%, 100% and 105% voltage levels for utility and nothing in distribution level!
Are we really responsible for this much fluctuation in utility voltage? I thought we consider only 2% fluctuation (and relays should trip for more than 2%) and we are responsible for other scenarios that can happen in distribution level.
Do you know any IEEE or PIP standard that clarifies this?
I used to study load flow with normal voltage level for utility and define several scenarios in distribution level such as loosing an MCC etc.
I was looking at another study that has only 3 scenarios with 95%, 100% and 105% voltage levels for utility and nothing in distribution level!
Are we really responsible for this much fluctuation in utility voltage? I thought we consider only 2% fluctuation (and relays should trip for more than 2%) and we are responsible for other scenarios that can happen in distribution level.
Do you know any IEEE or PIP standard that clarifies this?






RE: load flow and motor starting studies
It defines the more popular voltage levels for transmission, distribution and services.
Typically, you can expect a +/-5% maximum variation from nominal voltages.
RE: load flow and motor starting studies
RE: load flow and motor starting studies
RE: load flow and motor starting studies
RE: load flow and motor starting studies
Doesn't it mean I should trip for more than 105% and less than 97.5%?
http://www.powerqualityworld.com/2011/04/ansi-c84-...
RE: load flow and motor starting studies
You should only trip protective relays in order to protect equipment from harm, not just because of a number in a standard. You might want to take a look at the ITIC curve. Tripping on anything inside the curve may expose your customers to unnecessary outages.
http://www.powerqualityworld.com/2011/04/itic-powe...
RE: load flow and motor starting studies
Thanks for information on ITIC curve.
What about load flow studies?
My ETAP shows reasonable results when I have 97.5% in utility (voltage in all feeders are greater than 90%).
I would be bellow 90% in many gears if I use 95% in the utility!
RE: load flow and motor starting studies
IEEE Std 399-1997 IEEE Recommended Practice for Industrial and Commercial Power Systems Analysis
RE: load flow and motor starting studies
I looked at Brown and Red books and they exactly talk about standard voltage ranges etc for different studies!