Star-Delta wirings polarity
Star-Delta wirings polarity
(OP)
Someone have an idea of the impact of having one of the 3 motor windings reversed (exemple: if wires U1-U2 and V1-V2 are connect normaly but W1-W2 are swapped.
Will it start, and if yes, what will append to the phases currents of the motor ? Two coils will be opposed to the reversed one? Will it result in unbalanced currents?
Thanks
Will it start, and if yes, what will append to the phases currents of the motor ? Two coils will be opposed to the reversed one? Will it result in unbalanced currents?
Thanks





RE: Star-Delta wirings polarity
Thanks.
RE: Star-Delta wirings polarity
RE: Star-Delta wirings polarity
RE: Star-Delta wirings polarity
If some load connected, you can't tell about running, but it will hum.
If respectable load connected, it will not run, but it will hum.
In all cases it will get hotter than normal and hopefully trip the protection before it burns.
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.
RE: Star-Delta wirings polarity
RE: Star-Delta wirings polarity
On a compressor we have a 150 HP rebuilt motor, 575V , 6 wires (3 windings) , control by a set of 3 (new)contactors for proper star-delta running.
Windings are equals in resistance ( 0,0310 0,0312 0,0309 ohm) Voltages delta is acceptable (577 581 587)
Lines currents With Load are(142 152 165)and phases currents are (102 70 93)
Lines currents Without Load ( 62 55 74)and phases currents are ( 50 18 44)...!
The compressor run well! motor don't overheat ...but overloads tripped 5 or 6 times and also, a 225A fuse blow once on phase 1 and an other day on phase 2 ) ...all that in approx. 20 days and usualy at start.
I would like to find an answer to those unbalanced Phases currents , i know voltage do affect it in part (arround 4 percents)...but not enougth to explain a currents variation like 50 18 44 !
Unfortunately this compressor can not be stop to long, and doing tests like reversing a winding on a 150 Hp is a high risk, that's the reason why i joinned your intelligent work forum...theory before practice.
(Thank you for the first answers and specialy squeeky for the test!)
I stay tune...
RE: Star-Delta wirings polarity
For these voltages the voltage unbalance is below the 1% and it can not be the reason for the enormous difference in the currents.
- First, you need to measure the currents for two different phase-arrangements (L1, L2, L3 and L2, L3, L1) in order to determine whether the reason for the unbalance is in the motor or supply.
- The reason for the fuse blow may be a well known issue with star-delta starter in a short period of (no-voltage) time between the "start" (star) and "run" (delta) position.
http://winding.wix.com/design
RE: Star-Delta wirings polarity
I would check all the power wiring and cables. Is there a field isolator? If so, it will be a six pole unit. Any problem there?
What was done to the compressor motor prior to the problem starting? Was this from new? When you trip the overload is it at the transition from star to delta or on start up. Same question for the fuses.
RE: Star-Delta wirings polarity
Bill
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"Why not the best?"
Jimmy Carter
RE: Star-Delta wirings polarity
RE: Star-Delta wirings polarity
thread237-270521: 6-Lead Induction Motor - Swap Leads 1 and 4?
Hook up an oscope with 3+ channels to all three phases, observing marked lead polarity. Manually rotate the motor and you should see a small induced voltage. If hooked properly, you can see the normal pattern of three phases all approx 120 degrees apart. If hooked improperly, one phase is flipped 180, so phase relationship changes dramatically to be something like 3 positive peaks 60 degrees apart followed by 3 negative peaks 60 degrees apart.
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(2B)+(2B)' ?
RE: Star-Delta wirings polarity
If so, my guess is that the T2-T5 phase is reversed.