We have an inline pump with a 150HP/3 phase 460V, 165A nameplate vertical motor, Delta Start, Delta Run (6 leads). The pump and motor were out of service for over a year and recently serviced and moved to a new installation at a different facility. The new installation is a similar application in that it is being used for the transfer of #6oil between two bulk storage tanks. We are using an Allen Bradley SMC Flex Soft Start. We have the start and run leads wired in parallel. The motor starts and comes up to speed but is drawing about 215Amps when running ruinning at its normal operating point (2000gpm @ 200ft head). When we choke down on flow the current drops but to about 190A but can never get it to the 165A. The motor is a RELIANCE Motor from 1994. I obtained the factory information from the nameplate serial number. The factory cut sheet states a 208V motor. I just noticed that the current nameplate was originally stamped for 208V but then 'XX' out and re-stamped for 460V. Could this voltage conversion/rewinding be the cause of the issue?
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3 Phase Motor Current Draw HIGH 3
- Thread starter tlona
- Start date
Did you try to use the "Inside the Delta" wiring scheme for that Soft Starter because of the 6 leads? If so, that's the problem. The "Inside the Delta" scheme is for Wye-Delta wound motors ONLY. That's NOT what you have, it's a Part Winding motor. So in effect, you are trying to run the load on 60% of the motor, and it is overloading. The fix for that is to simply parallel the 2 sets of leads and run the motor through the soft starter as an "in line" configuration. The one caveat however is that the Soft Stater must be sized for the FULL MOTOR FLA, whereas when used "Inside the Delta", it is rated for 58% of the motor FLA.
" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden
" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden
- Thread starter
- #22
No we didnt wire it "inside the Delta" only 3 leads going to motor. As far as the 600ssu yes we contacted the pump vendor and they ran some curves for us to see about shaving impeller. We choked down on the discharge to reduce flow, amps dropped but not to the rated 165. Previous application was 6 oil
Have you checked the accuracy of your ammeter?
165 Amps x 12 Volts = 2 KVA
Two 2 KVA at 480/12 Volt buck transformers will drop the voltage to about 458 Volts.
If this is a saturation issue that will fix it.
Can you drain the pump housing and do a no load run?
Bill
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"Why not the best?"
Jimmy Carter
Were you able to choke the flow down to zero flow?
165 Amps x 12 Volts = 2 KVA
Two 2 KVA at 480/12 Volt buck transformers will drop the voltage to about 458 Volts.
If this is a saturation issue that will fix it.
Can you drain the pump housing and do a no load run?
Bill
--------------------
"Why not the best?"
Jimmy Carter
Edison; Thanks for answering my question.
I agree with you Bill on the saturation. That certainly creates "mystery over-current".
Keith Cress
kcress -
I agree with you Bill on the saturation. That certainly creates "mystery over-current".
Keith Cress
kcress -
I don't agree with rotation only.
Don't forget back EMF.
The back EMF of each phase winding must be in phase with the supply voltage.
If the connections of the second winding are "rolled" the back EMF will be 120 degrees out of phase with the supply voltage.
Bill
--------------------
"Why not the best?"
Jimmy Carter
Don't forget back EMF.
The back EMF of each phase winding must be in phase with the supply voltage.
If the connections of the second winding are "rolled" the back EMF will be 120 degrees out of phase with the supply voltage.
Bill
--------------------
"Why not the best?"
Jimmy Carter
LittleInch
Petroleum
The problem with shaving the impeller is that it cuts the differential head down. So be careful what you wish for and unless you are always throttling to get 2,000 gpm then you might not have much pressure to spare.
When you say you "choked it down", to what flow? Depending on the pump curve the decrease in efficiency might have a big impact on power for quite a large flow drop.
The 470V clearly might have an impact, but get the load / duty right first. IMHO.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
When you say you "choked it down", to what flow? Depending on the pump curve the decrease in efficiency might have a big impact on power for quite a large flow drop.
The 470V clearly might have an impact, but get the load / duty right first. IMHO.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
LionelHutz
Electrical
The facility at 470VAC should not be causing the motor to saturate. Typical utilization voltage is 480VAC.
You have to confirm the motor is OK first before chasing the pump. It doesn't make any sense to do it the other way.
Run it uncoupled. If the current is still high, then run it uncoupled with only 1 winding connected. Measure from one lead of the unconnected winding to each of the leads of the connected winding. Finding a measurement of ~0V tells you those 2 leads go together. Repeat for the other leads of the unconnected winding. You should find there is only 1 connection combination that works.
You have to confirm the motor is OK first before chasing the pump. It doesn't make any sense to do it the other way.
Run it uncoupled. If the current is still high, then run it uncoupled with only 1 winding connected. Measure from one lead of the unconnected winding to each of the leads of the connected winding. Finding a measurement of ~0V tells you those 2 leads go together. Repeat for the other leads of the unconnected winding. You should find there is only 1 connection combination that works.
Lionel. normally I would agree with you.
What makes me consider saturation is that this motor was re-rated from 208 Volts to 460 Volts.
The age of the motor dates back to when 440 Volts was still common in older industries.
It is possible that rather than a rewind the motor coil groups were reconnected for a higher voltage.
At the same V/Hz ratio, that would be a rated voltage of 416 Volts.
This is why I considered saturation as a possible factor to be ruled out.
I have seen it done wrong.
When the supply voltage hit the back EMF the smoke came out.
Two 40 HP fans with a common control.
When they were connected the 9 was read as a 6. Instead of a sequence of 1-7, 2-8, 3-9. they were connected in a sequence of 1-6, 2-7, 3-8.
The first motor started and stopped with a bang.
A few seconds later the automatic starting sequence started the second motor which stopped with a bang.
The motor shop told us that the internal wye connections had been blown apart, no other damage.
The motor shop said that the motors were under warranty.
I told them that maybe we shouldn't get a free repair as the motors had been connected wrongly.
The reply;
"Those connections should have withstood that. We will fix the motors under warranty."
The point is that if the motor ran long enough to take Amp readings, and even ran more than once, it is probably connected correctly.
Bill
--------------------
"Why not the best?"
Jimmy Carter
What makes me consider saturation is that this motor was re-rated from 208 Volts to 460 Volts.
The age of the motor dates back to when 440 Volts was still common in older industries.
It is possible that rather than a rewind the motor coil groups were reconnected for a higher voltage.
At the same V/Hz ratio, that would be a rated voltage of 416 Volts.
This is why I considered saturation as a possible factor to be ruled out.
I agree 100%.
I have seen it done wrong.
When the supply voltage hit the back EMF the smoke came out.
Two 40 HP fans with a common control.
When they were connected the 9 was read as a 6. Instead of a sequence of 1-7, 2-8, 3-9. they were connected in a sequence of 1-6, 2-7, 3-8.
The first motor started and stopped with a bang.
A few seconds later the automatic starting sequence started the second motor which stopped with a bang.
The motor shop told us that the internal wye connections had been blown apart, no other damage.
The motor shop said that the motors were under warranty.
I told them that maybe we shouldn't get a free repair as the motors had been connected wrongly.
The reply;
"Those connections should have withstood that. We will fix the motors under warranty."
The point is that if the motor ran long enough to take Amp readings, and even ran more than once, it is probably connected correctly.
Bill
--------------------
"Why not the best?"
Jimmy Carter
tiona said:
The question I have is, exactly what pattern did the rewinder rewind to? Was it the LV pattern or the HV pattern when they converted it to 460V? You only mention the external connections you would use, which is fine, but how are 4, 5 and 6 connected inside of the motor?
" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden
- Thread starter
- #30
I dont know what the current was uncoupled as we received the call from the electrician who stated that it ran fine uncoupled but drew high current when coupled and flowing product. We have a gate valve on the discharge and when first started and up to run speed the motor drew about 260amps with about a 60psig delta so we "choked down" on the gate valve to get the 90psi delta and the amps dropped. The more we "choked on the gate" the amps dropped but never to the rated current. We also never deadheaded the motor. We are actually gonna drain and do a no load test next week. Based on our run time and tank levels we were able to obtain a flow rate which matched the pump curve head. There are neither 4,5,6 external nor internal connections for this motor. The manf. wiring diagram shows two deltas (1,2,3) and (7,8,9). 1,2,3 are identified as start and 1-7, 2-8, 3-9 identified as run. There is no history on how the motor was rewound only that the factory states its 208V and the nameplate has been changed and the last installation it operated at 460v. What actually takes place when converting a 208V motor to 460? Wouldnt the original 208v winding have more/larger copper?
They 208 Volt winding would be made up of two windings in parallel.
In series the voltage would be 416 Volts.
The change from parallel to series is usually easy.
There may have been 9 leads originally and it is a simple re-connection.
The problem is when connected in series it is the equivalent of one higher voltage winding and for part winding start you need two windings. (Often but not always identical.)
Each winding may be made up of groups of coils.
If some coils are in parallel then while not as easy it may be possible to locate and open the connections between coils and re-connect for a higher voltage.
Any re-connection will be a lot cheaper than a rewind.
To go from 208 to 460 Volts would require the more expensive re-wind.
It is not a 2:1 ratio and cannot be achieved with a change from parallel to series.
The motor may have been a 208/230:460 Volt rated motor, in which case it should not saturate at 470 Volts.
Most part winding start motors are used at the lower voltage. Many, but not all dual voltage motors are suitable for use as part winding motors at the lower voltage.
Summery:
208 Volt Part Winding Start motors are not common.
460 Volt Part Winding Start motors are a very small percentage of the number of 208 Volt Part Winding Start motors.
When a 9 lead motor is prepared for use as a part Winding Start motor, the 4, 5, and 6 leads are star connected internally and often are not brought out.
Bill
--------------------
"Why not the best?"
Jimmy Carter
In series the voltage would be 416 Volts.
The change from parallel to series is usually easy.
There may have been 9 leads originally and it is a simple re-connection.
The problem is when connected in series it is the equivalent of one higher voltage winding and for part winding start you need two windings. (Often but not always identical.)
Each winding may be made up of groups of coils.
If some coils are in parallel then while not as easy it may be possible to locate and open the connections between coils and re-connect for a higher voltage.
Any re-connection will be a lot cheaper than a rewind.
To go from 208 to 460 Volts would require the more expensive re-wind.
It is not a 2:1 ratio and cannot be achieved with a change from parallel to series.
The motor may have been a 208/230:460 Volt rated motor, in which case it should not saturate at 470 Volts.
Most part winding start motors are used at the lower voltage. Many, but not all dual voltage motors are suitable for use as part winding motors at the lower voltage.
Summery:
208 Volt Part Winding Start motors are not common.
460 Volt Part Winding Start motors are a very small percentage of the number of 208 Volt Part Winding Start motors.
When a 9 lead motor is prepared for use as a part Winding Start motor, the 4, 5, and 6 leads are star connected internally and often are not brought out.
Bill
--------------------
"Why not the best?"
Jimmy Carter
A 9 lead motor that is internally connected in delta may not be used for Part Winding Start by re-connecting the existing leads.
For instance the #1 lead of a delta connected motor is connected to two windings, ending in #4 and in #9.
For use as a Part Winding Start motor these winding ends must be separated.
In effect the 9 lead motor must first be converted to a 12 lead motor.
Bill
--------------------
"Why not the best?"
Jimmy Carter
For instance the #1 lead of a delta connected motor is connected to two windings, ending in #4 and in #9.
For use as a Part Winding Start motor these winding ends must be separated.
In effect the 9 lead motor must first be converted to a 12 lead motor.
Bill
--------------------
"Why not the best?"
Jimmy Carter
LionelHutz
Electrical
You MUST go back to basics. Run the motor only without the pump because ONLY then can you start to troubleshooting the issue. No point posting pages of possibilities on how the motor is bad without even knowing the motor is causing the issue.
I would never go back to a shop that thought they could get away with re-connecting an old motor from parallel 208V windings to series 480V windings. The motor was likely re-wound completely at one point in it's life.
I would never go back to a shop that thought they could get away with re-connecting an old motor from parallel 208V windings to series 480V windings. The motor was likely re-wound completely at one point in it's life.
- Thread starter
- #34
[!]For your click-less pleasure.[/!]
Looking up double winding delta start I saw it described as 'don't stay on one winding for more than 1 second or it's toast'. This true?
Keith Cress
kcress -
Looking up double winding delta start I saw it described as 'don't stay on one winding for more than 1 second or it's toast'. This true?
Keith Cress
kcress -
LionelHutz
Electrical
Keith, with a load yes you need to limit operation on a single winding.
-
1
- #39
the electrician who stated that it ran fine uncoupled but drew high current when coupled and flowing product
The no load current, starting torque, starting current or even the starting method is not the issue here. Motor's higher current on load is load related, not motor related.
Muthu
The no load current, starting torque, starting current or even the starting method is not the issue here. Motor's higher current on load is load related, not motor related.
Muthu
I missed that.edison123 said:
Running fine unloaded rules out saturation.
Try choking it further.tiona said:
I have had pumps that took a lot of restriction to bring the current down.
Bill
--------------------
"Why not the best?"
Jimmy Carter
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