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
LittleInch
Petroleum
Is it going the right way around?
How are you measuring SG of the fluid, pressure and flow?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
How are you measuring SG of the fluid, pressure and flow?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
- Thread starter
- #3
Have you checked the voltage to the motor when it's running? Low voltage will definitely raise the amps. Could be you have a problem (current choke point) somewhere that allows full voltage when not running but drops a lot of voltage under load.
The start and run leads in parallel.. Was this as it was originally wired in the first installation?
I have to admit I'm not sure what a 'start' winding is doing on a three phase induction motor.
Keith Cress
kcress -
The start and run leads in parallel.. Was this as it was originally wired in the first installation?
I have to admit I'm not sure what a 'start' winding is doing on a three phase induction motor.
Keith Cress
kcress -
- Thread starter
- #5
Yes voltage is OK. No one knows how it was wired in original installation. My guess it was a two stage starting contactor. I am use to seeing a wye start, delta run but this motor is delta start & delta run. The manf. wiring diagram shows (2) deltas 1,2,3 and 7,8,9. where only 1,2,3 for start then 1-7, 2-8, 3-9 for run.
tlona
The lead labeling 1,2,3 and 7,8,9 are indicating the motor is designed for PWS so the manufacturer wiring diagram is correct: "1,2,3 for start then 1-7, 2-8, 3-9 for run" but the soft starter is not the problem; if the motor is drawing high current I will check motor loading -Ask if somebody replaces or trimmed the impeller, also ask or verify if in the old application they were using different settings for the pumping limiting the motor load.
Best Regards
Petronila
The lead labeling 1,2,3 and 7,8,9 are indicating the motor is designed for PWS so the manufacturer wiring diagram is correct: "1,2,3 for start then 1-7, 2-8, 3-9 for run" but the soft starter is not the problem; if the motor is drawing high current I will check motor loading -Ask if somebody replaces or trimmed the impeller, also ask or verify if in the old application they were using different settings for the pumping limiting the motor load.
Best Regards
Petronila
Sounds like a part winding start motor with two sets of stator winding and only one is used during starting. Using one winding increases the winding impedance thereby reducing the starting current. This is mostly used in air-conditioning systems. But it is very short time rated (not more than 5 seconds) and the stating torque may not be sufficient to achieve full speed and it would require the second winding to be powered to accelerate to full speed.
Having said that, your running current is more of load related than the motor itself. I would check the present pump curve for its prime mover power requirement.
Muthu
Having said that, your running current is more of load related than the motor itself. I would check the present pump curve for its prime mover power requirement.
Muthu
Dear Mr. tlona
Q1. " a)...We have an inline pump with a 150HP/3 phase 460V, 165A nameplate vertical motor, Delta Start, Delta Run (6 leads), pump and motor. ....b) We are using an Allen Bradley SMC Flex Soft Start... c) No one knows how it was wired in original installation. d) My guess it was a two stage starting contactor. I am use to...e)The manf. wiring diagram shows (2) deltas 1,2,3 and 7,8,9. where only 1,2,3 for start then 1-7, 2-8, 3-9 for run."
A1. a) it is (unusual?) for a [single-speed three-phase] motor with " Delta Start, Delta Run ". Could it be a [two-speed] motor with delta 1,2,3 for low-speed and 1-7,2-8,3-9 for high-speed ?.
b) it is unlikely that an Allen Bradley SMC Flex Soft Start.. would do the job, unless you have external contactor to short 1-7, 2-8, 3-9 at run. BTW. the soft starter has only one ramp-up voltage from low for start to final run voltage and by-pass by a contactor externally/internally if included.
c) ----
d) for single-speed three-phase motors, it is unnecessary to have start and run windings. However, it is usual for a two-speed motor to start at low speed during starting and automatically/manually transfers to high-speed on run.
e) the soft starter can only be connected to 1,2,3. Shorting (1-7), (2-8), (3-9) would have to be done by external contact; when the SS is at full speed on run.
Che Kuan Yau (Singapore)
Q1. " a)...We have an inline pump with a 150HP/3 phase 460V, 165A nameplate vertical motor, Delta Start, Delta Run (6 leads), pump and motor. ....b) We are using an Allen Bradley SMC Flex Soft Start... c) No one knows how it was wired in original installation. d) My guess it was a two stage starting contactor. I am use to...e)The manf. wiring diagram shows (2) deltas 1,2,3 and 7,8,9. where only 1,2,3 for start then 1-7, 2-8, 3-9 for run."
A1. a) it is (unusual?) for a [single-speed three-phase] motor with " Delta Start, Delta Run ". Could it be a [two-speed] motor with delta 1,2,3 for low-speed and 1-7,2-8,3-9 for high-speed ?.
b) it is unlikely that an Allen Bradley SMC Flex Soft Start.. would do the job, unless you have external contactor to short 1-7, 2-8, 3-9 at run. BTW. the soft starter has only one ramp-up voltage from low for start to final run voltage and by-pass by a contactor externally/internally if included.
c) ----
d) for single-speed three-phase motors, it is unnecessary to have start and run windings. However, it is usual for a two-speed motor to start at low speed during starting and automatically/manually transfers to high-speed on run.
e) the soft starter can only be connected to 1,2,3. Shorting (1-7), (2-8), (3-9) would have to be done by external contact; when the SS is at full speed on run.
Che Kuan Yau (Singapore)
Mr. Che, Respectfully;
Part winding starting is a standard feature with North American motors.
The connections shown are the standard part winding connections.
That said, it is unusual as you said in that it is not often used.
When it is used, it is most often used for fairly large fan loads on smaller 120/208 Volt services.
The few that I have encountered have been used to start relatively large fans
For those connections you would need all 460 Volt rated windings. This is unusual but possible.
However if the voltage at the new site is running higher than the old site you may be approaching saturation.
Throttling the discharge to zero should drastically reduce the current, unless the motor is saturating.
I was under the impression the trimming the impeller generally lowers the motor current, all else being equal.
Am I mistaken here?
Bill
--------------------
"Why not the best?"
Jimmy Carter
Part winding starting is a standard feature with North American motors.
The connections shown are the standard part winding connections.
That said, it is unusual as you said in that it is not often used.
When it is used, it is most often used for fairly large fan loads on smaller 120/208 Volt services.
The few that I have encountered have been used to start relatively large fans
For those connections you would need all 460 Volt rated windings. This is unusual but possible.
However if the voltage at the new site is running higher than the old site you may be approaching saturation.
Throttling the discharge to zero should drastically reduce the current, unless the motor is saturating.
I was under the impression the trimming the impeller generally lowers the motor current, all else being equal.
Am I mistaken here?
Bill
--------------------
"Why not the best?"
Jimmy Carter
The start time at pws motors must not exceed 1 second.
Also, you cannot apply two types of motor start-up at the same time: pws and soft-start.
Electric motor repair/design
Also, you cannot apply two types of motor start-up at the same time: pws and soft-start.
Electric motor repair/design
Yes Bill, trimming drops loading.
tlona; I'm guessing you may have the wires crossed on the start winding.
Someone know how to "phase 6 wires coming out of a delta start/run motor"?
Clearly, they can be grouped into the two winding sets simply by continuity since they should have no connection.
But then how do you figure out which are the two A-phases, B-phases, etc.?
Keith Cress
kcress -
tlona; I'm guessing you may have the wires crossed on the start winding.
Someone know how to "phase 6 wires coming out of a delta start/run motor"?
Clearly, they can be grouped into the two winding sets simply by continuity since they should have no connection.
But then how do you figure out which are the two A-phases, B-phases, etc.?
Keith Cress
kcress -
-
1
- #13
A wrong connection will result in extemely high current, not just high current.
We once had a pair of 40 HP fans connected out of sequence.
It actually blew apart some internal connections.
A bang, some smoke, and the motors did not start.
tiona: Is the current high on all three phases or just on one or two phases?
High current on one or two phases is a supply unbalance issue.
High current on all three phases, even with the discharge completely 100% throttled may be saturation.
That is, the voltage is too high for the motor windings.
That could easily happen if the motor has been re-wound at a ratio of 2:1 instead of a ratio of 2.12:1 (460/208)
The voltage should be checked to either identify or rule out this possibility.
When checking the voltage on a problem motor circuit the line to neutral voltage is unimportant.
The line to line voltages must be checked and compared.
High voltage approaching saturation will cause high current on three phases.
Supply unbalance will cause high current on one or two phases.
Bill
--------------------
"Why not the best?"
Jimmy Carter
We once had a pair of 40 HP fans connected out of sequence.
It actually blew apart some internal connections.
A bang, some smoke, and the motors did not start.
tiona: Is the current high on all three phases or just on one or two phases?
High current on one or two phases is a supply unbalance issue.
High current on all three phases, even with the discharge completely 100% throttled may be saturation.
That is, the voltage is too high for the motor windings.
That could easily happen if the motor has been re-wound at a ratio of 2:1 instead of a ratio of 2.12:1 (460/208)
The voltage should be checked to either identify or rule out this possibility.
When checking the voltage on a problem motor circuit the line to neutral voltage is unimportant.
The line to line voltages must be checked and compared.
High voltage approaching saturation will cause high current on three phases.
Supply unbalance will cause high current on one or two phases.
Bill
--------------------
"Why not the best?"
Jimmy Carter
-
1
- #14
Keith
But then how do you figure out which are the two A-phases, B-phases, etc.?
The leads are normally tagged 1,2,3 and 7,8,9 or some such letters. Even if they are not tagged, not a biggie. You temporarily tag the leads as 1,2,3 and 7,8,9, and after making sure there no continuity between 1,2,3 and 7,8,9, apply the same sequence voltage to both the windings in open shaft and note the rotation direction. If it rotates in the same direction, you retain the tags. If not, you switch 7&8 and retag them as 7&8.
Muthu
But then how do you figure out which are the two A-phases, B-phases, etc.?
The leads are normally tagged 1,2,3 and 7,8,9 or some such letters. Even if they are not tagged, not a biggie. You temporarily tag the leads as 1,2,3 and 7,8,9, and after making sure there no continuity between 1,2,3 and 7,8,9, apply the same sequence voltage to both the windings in open shaft and note the rotation direction. If it rotates in the same direction, you retain the tags. If not, you switch 7&8 and retag them as 7&8.
Muthu
- Thread starter
- #15
Thank-you all for the input. YES the current and voltage is balanced in all three phases. The voltage at this facility is 470V. I do not know what the voltage at the previous facility was. The manf wiring clearly shows the 1,2,3 as the start winding and then connecting 1-7, 2-8 & 3-9 for run which would was typical back in the day for reduced voltage motor starting. We simply just have it wired in the RUN configuration. the motor starts and gets up to speed. I was questioning how the motor was rewound/converted from 208 to 460 but no records. Over saturation fits what we are observing in the field. Thank-you all for the input. We have another motor we can try that we know has not been rewound. Will look at replacing the motor and possible shaving the impeller. Thank-you
LittleInch
Petroleum
Still think you need to look at the load.
Have you actually measured flow and pressure differential?
Actually seen rotation is correct as far as the pump is concerned?
Could the efficiency have changed somehow on the pump? Do you have the pump curve?
Are you flowing more?
2000 USgpm @ 200 ft differential head of a 0.99 SG fluid with a 70% pump efficiency gives about 145hp shaft power. Motor efficiency is ?? Power factor is??
To get 150hp (112kW) to equal 165 A at 460V you have a power factor of 0.85?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
Have you actually measured flow and pressure differential?
Actually seen rotation is correct as far as the pump is concerned?
Could the efficiency have changed somehow on the pump? Do you have the pump curve?
Are you flowing more?
2000 USgpm @ 200 ft differential head of a 0.99 SG fluid with a 70% pump efficiency gives about 145hp shaft power. Motor efficiency is ?? Power factor is??
To get 150hp (112kW) to equal 165 A at 460V you have a power factor of 0.85?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
LionelHutz
Electrical
What current do you get if you decouple the motor?
A soft-starter will work just fine on that motor. Connect it in the run configuration to the soft-starter.
A soft-starter will work just fine on that motor. Connect it in the run configuration to the soft-starter.
electricpete
Electrical
I'm not sure what kind of oil you've got, but if it's high viscosity, the power draw can vary widely with viscosity grade and oil temperature (cold is worst case...admittedly doesn't seem likely this time of year)
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(2B)+(2B)' ?
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(2B)+(2B)' ?
- Thread starter
- #19
Not sure about current on uncoupled motor current but can check. Name plate states a NEMA nom eff. of 96.2 and Guaranteed eff of 95.8. Yes we have a curve and been working with pump manf. We recorded differential pressure and based the flow rate on the runtime and change in tank levels. Appears to be in line with pump curve. PF of motor is 88.5. Product is 6 oil at 125, 600SSU
LittleInch
Petroleum
600SSU seems to be about 120 cSt so fairly viscous.
At this viscosity the pump curves need adjustment by about 10% and seems to significantly affect the efficiency. So in my calculation I used 70%, but could be 50%....
50% efficiency gets you 204 hp, so about 220A?? at 2000 gpm and 200 ft.
Also at the start you could get more flow which averages ok over time but at the start might be higher due to high levels in the inlet tank.
Need to talk to the pump vendor.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
At this viscosity the pump curves need adjustment by about 10% and seems to significantly affect the efficiency. So in my calculation I used 70%, but could be 50%....
50% efficiency gets you 204 hp, so about 220A?? at 2000 gpm and 200 ft.
Also at the start you could get more flow which averages ok over time but at the start might be higher due to high levels in the inlet tank.
Need to talk to the pump vendor.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
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