Unbalance current in generator phases
Unbalance current in generator phases
(OP)
Hi all,
I encountered a problem that we are running 10 generators of 415volts in parallel. In 2 generators out of 10 generators, we have 100 ampere high in B phase. We also verify this high current by other sources too, so what is the cause behind this??? If we have unbalanced load so every generator should have same problem because all generators run in parallel.So please help in this regard.
I encountered a problem that we are running 10 generators of 415volts in parallel. In 2 generators out of 10 generators, we have 100 ampere high in B phase. We also verify this high current by other sources too, so what is the cause behind this??? If we have unbalanced load so every generator should have same problem because all generators run in parallel.So please help in this regard.






RE: Unbalance current in generator phases
Normal full load current?
Age of mechines/installation?
Has this issue been present since new or has it developed recently?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Unbalance current in generator phases
1850Amp
2 years
Not confirmed...i have noted this since last month.
RE: Unbalance current in generator phases
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Unbalance current in generator phases
RE: Unbalance current in generator phases
RE: Unbalance current in generator phases
RE: Unbalance current in generator phases
RE: Unbalance current in generator phases
RE: Unbalance current in generator phases
Paralleling dissimilar generators with different pitch angle can give rise to high levels of current flowing on the neutral/harmonic current (imbalance). Have you measured the neutral?
Best results are paralleling generators with same pitch angle.
See the following paper for additional information: http://power.cummins.com/sites/default/files/literature/technicalpapers/PT-9016-P2-Dissimilar-en.pdf
RE: Unbalance current in generator phases
I don't intend to speak for David, but what I've always understood that term to mean is to [a] take a full set of system and generator phase current readings with the unit in question on load, then [b] remove it from service, [c] establish isolation and work protection, [d] disconnect A phase generator winding and connect it to the B phase of the system, disconnect B generator phase and connect it to C phase of the system, and disconnect C generator phase and connect it to A phase of the system, [e] remove work protection, then [f] place the unit in service; once loaded, [g] take another full set of readings and see which phase now shows high or low current compared to the previous readings. The results will indicate whether the problem is system induced or within the generator itself.
CR
"As iron sharpens iron, so one person sharpens another." [Proverbs 27:17, NIV]
RE: Unbalance current in generator phases
RE: Unbalance current in generator phases
Who makes the generator end can have an influence, one manufacturer I know of uses a process called "square lam" in how they cut the stator steel, it results in a slight phase to phase variation that can cause the types of problems you are seeing. Before you roll phases (make sure you maintain sequence if you do and recheck rotation before paralleling again) I would take a pretty complete set of measurements with a high quality test instrument. We had a number of generators that had the phase leads improperly marked and had to do as David described to get everything playing nice again.
I recently worked on a system with a similar complaint that ended up being a combination of some damaged CT's (mounted out in the generator) and some wiring problems giving reading errors. A good quality three phase analyzer may be helpful to make sure you don't have something odd going on and to help you see everything at once.
Hope that helps, MikeL
RE: Unbalance current in generator phases
We have about 40 to 60 amperes on our neutral. Yes rodney i know pitch angle problem in parallel generators but this system is very old. Expansion take place years by years that why here we have different pitch configuration generators.
I will share our SLD in later evening.
I have confirmed from individual three meters that one phase ampere was high.
RE: Unbalance current in generator phases
One of our generators output current has unbalanced current.
What is cause of generator unbalanced current?
What is its cause possibly?
Six similar Genset connected to one bus. One of those Gensets have unbalanced current.
Is it possible its because of air gap of the failed phase?
What is solution for this problem?
What is cause of generator unbalanced current?
Regards
RE: Unbalance current in generator phases
RE: Unbalance current in generator phases
I measured frequency with HoldPeak HP870N which shows first harmonic 50 (49.98)Hz for three phase, however S-phase at first was about 234 Hz and after one second it change to 50 Hz.
All gens are work in a place with similar air conditioner design and so on.
What do you think?
RE: Unbalance current in generator phases
Thank you.
Here it is our power plant gens currents:
gen1:
R=1677
S=1596
T=1540
gen2:
R=1524
S=1362
T=1360
gen3:
R=1220
S=1394
T=1351
gen4=
R=1239
S=1188
T=1195
All bus voltages are 400v.
What do you think about this?
RE: Unbalance current in generator phases
Bill
--------------------
"Why not the best?"
Jimmy Carter