New Member, Power System Operator, AMA
- Thread starter MVAR
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Lol, I was trying to avoid the “foam of the beer” reactive power description
Thanks for the welcome.
What role & interconnection are you in? I’m on mobile right now so members locations don’t show up if listed
Mate, in the Australian NEM...
Joined the industry as a mechanical engineering Cadet in 1989, post uni a bit in transmission, then power station construction, project management, turbine engineer, coal ash and dust manager, performance manager, operations manager...etc.
Oh and the beer equivalentvand tap changer was a poor industry pun...
Joined the industry as a mechanical engineering Cadet in 1989, post uni a bit in transmission, then power station construction, project management, turbine engineer, coal ash and dust manager, performance manager, operations manager...etc.
Oh and the beer equivalentvand tap changer was a poor industry pun...
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- Jun 8, 2022
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So I am a complete amateur at attempting to understand the electric grid.
My current pre-k stumbling block is 3 phase at the street level. I think I understand up to there - generation power is stepped up for 3 phase transmission (3 conductors and a ground for safety) and then stepped down at a local subsation(s) to eventually get to 720V 3 phase. That 720V 3 phase is sent out to the residential communities where a single phase tap is sent to a transformer down the street from my house that powers 4 or 5 houses I believe (its all underground here).
My question - is since each of these single phases locally now have completely different loads, how is this 720V / 3 phase local system kept in balance? Is that a function of the substation transformer or my local transformer or some other magic?
My current pre-k stumbling block is 3 phase at the street level. I think I understand up to there - generation power is stepped up for 3 phase transmission (3 conductors and a ground for safety) and then stepped down at a local subsation(s) to eventually get to 720V 3 phase. That 720V 3 phase is sent out to the residential communities where a single phase tap is sent to a transformer down the street from my house that powers 4 or 5 houses I believe (its all underground here).
My question - is since each of these single phases locally now have completely different loads, how is this 720V / 3 phase local system kept in balance? Is that a function of the substation transformer or my local transformer or some other magic?
Had a good time with a few GE engineers during majors back when I was a plant operator. Those guys got worked to the bone.
Relay Techs were my go-to as a transmission operator. Had a few SEL & GE solid state relays I couldn't remote into throughout my former control area. Those guys were a life saver at times.
Enjoy retirement. That's my largest current "expense" is retirement savings.
I never worked on the DO (Distribution) side but would see some of those guys from time to time.
The OE (Operations Engineer) will calculate individual phase loading for circuits. Where you are on that circuit will determine which phase you are tapped onto. Not all phases on the transmission system are balanced as well as one would hope but the distribution system has larger delta's.
I knew you were joking about the beer & LTC. I got a small chuckle out of it.
When the distribution load gets too far out of balance , the line crews will actually go out and move load to another phase by removing the stinger on the transformer and attach it to another phase . Same can be done with primary taps off of the main three phase circuit . Sometimes it isn't magic , it's just the guy in the field .
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If I may, given that even the balancing above is never perfect - does the ground become a neutral, or how far out of balance can it actually get before there is a problem?When the distribution load gets too far out of balance , the line crews will actually go out and move load to another phase by removing the stinger on the transformer and attach it to another phase . Same can be done with primary taps off of the main three phase circuit . Sometimes it isn't magic , it's just the guy in the field .
2% phase imbalance was considered the maximum allowable in transmission operations with a 1% or lower as a target. 2% was also the maximum allowable on the sub-transmission 60-70kV system. I never saw a 2% imbalance on 230kV or 500kV lines as that would be pretty drastic. Currently my largest delta is 5kV between phases on one 230kV line in my entire system.
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