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Submersible motors 3
- Thread starter Grover194
- Start date
Grover194
Our pumps do not directly bolt to the type motors you are looking at due to different bolt patterns, but we do use this type motor on occasion. We have a machine shop make a spool adapter and coupling for us to fit between the pump and motor. You could have an adapter made to gain access to the motor.
It depends on how the pump is made, but you may be able to gain access to the shaft at the top end of the pump with an adapter.
The amount of slip is going to be dependant on the motor design. To make a reasonable calculation of rotating speed or slip you may want to contact the manufacture and see if they can offer possible information.
The amount of accuracy that you require is going to drive the cost of the method used.
Good Luck
Our pumps do not directly bolt to the type motors you are looking at due to different bolt patterns, but we do use this type motor on occasion. We have a machine shop make a spool adapter and coupling for us to fit between the pump and motor. You could have an adapter made to gain access to the motor.
It depends on how the pump is made, but you may be able to gain access to the shaft at the top end of the pump with an adapter.
The amount of slip is going to be dependant on the motor design. To make a reasonable calculation of rotating speed or slip you may want to contact the manufacture and see if they can offer possible information.
The amount of accuracy that you require is going to drive the cost of the method used.
Good Luck
acmotorengineer
Electrical
depending on how accurate you want to know speed - for approximate speed, you can ask the manufacturer for a running speed vs current curve at operating voltage and frequency.
HomeMadeSin
Mechanical
Has anyone tried to use acceleration probes like those used for developing bearing signatures? I'm sure you could rig up say 2 symmetrical features that make slight contact with something.....starting to sound like playing cards on the spokes of your bike. Sounds hokey, but when I was doing PM surveys at a papermill, we could pinpoint the rpm's of the equipment fairly well. Just a thought....
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1
- #6
Hi Grover
The Idea of a vibration Accelerometer would be ok if you could transform that analogue signal into a Vibration Spectra.An Overall value would not tell you the RPM.
There are very small EDDY current probes/Gap probes, that can be installed close to a moving shaft and pick up a keyway or something.This is fairly simply technology and reasonably accurate.They are also called Proximity probles.Try Bentley Nevada /Entek/IRD/Kadon Eng.
Good Luck
GusD
The Idea of a vibration Accelerometer would be ok if you could transform that analogue signal into a Vibration Spectra.An Overall value would not tell you the RPM.
There are very small EDDY current probes/Gap probes, that can be installed close to a moving shaft and pick up a keyway or something.This is fairly simply technology and reasonably accurate.They are also called Proximity probles.Try Bentley Nevada /Entek/IRD/Kadon Eng.
Good Luck
GusD
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2
- #7
Dear Mr. Grover,
Your basic problem semms to be measurement of the speed of a submersible motor, ie. when in submerged condition. I hope my assumption is correct.
There is a one method for measurement of the speed of submersible motors with much better reliability. However, this method can be used provided the performance test is being done in an open type of well or sump.
The main sensing device is called as Slip Coil, which is mounted over the stator portion of the motor.( at the centre of the stator ). As you may be aware, when the any induction motor starts, there is a back emf generated in the rotor. Due to the magnetic leakage, an emf is generated in the slip coil, with different frequency and is equal to the difference in the line ( supply frequency ) and the one generated by the rotor. To measure the slip, this signal is fed to a centre zero galvanometer, of which neddle oscillates exactly as per the differential frequency. this oscillations are counted and the speed is calculated.
In another method, a special disply instrument is connected to the out put of the slip coil and it displays directly the speed of motor.
The no. of turns and the I.D. of the coil is to be decided based on the stator length, operating voltage and this coil can be used for other motors having the O.D. smaller.
If you can provide me a little information about your motors, ie. the rating, operating voltage / frequency, motor OD etc. I can give you the details of this.
Before I end, let me tell you something about myself.
I am basically an electrical engineer working with KSB Pumps Ltd, India in Marketing department. I have 20 years of experience in the field of submersible bore hole pumps and submersible sewage pumps. My experience includes Research & Development for two years, design 7 years, projects 5 years and now looking after Projects in marketing department. In addition, I am excellent in the field of testing of motors, designing of instrument panels ( for performance testing )and control panels.
I hope this will be useful for you.
Rajendra Joshi
So if you have any problem like the one here, you ask and I will try to find a solution on it.
Your basic problem semms to be measurement of the speed of a submersible motor, ie. when in submerged condition. I hope my assumption is correct.
There is a one method for measurement of the speed of submersible motors with much better reliability. However, this method can be used provided the performance test is being done in an open type of well or sump.
The main sensing device is called as Slip Coil, which is mounted over the stator portion of the motor.( at the centre of the stator ). As you may be aware, when the any induction motor starts, there is a back emf generated in the rotor. Due to the magnetic leakage, an emf is generated in the slip coil, with different frequency and is equal to the difference in the line ( supply frequency ) and the one generated by the rotor. To measure the slip, this signal is fed to a centre zero galvanometer, of which neddle oscillates exactly as per the differential frequency. this oscillations are counted and the speed is calculated.
In another method, a special disply instrument is connected to the out put of the slip coil and it displays directly the speed of motor.
The no. of turns and the I.D. of the coil is to be decided based on the stator length, operating voltage and this coil can be used for other motors having the O.D. smaller.
If you can provide me a little information about your motors, ie. the rating, operating voltage / frequency, motor OD etc. I can give you the details of this.
Before I end, let me tell you something about myself.
I am basically an electrical engineer working with KSB Pumps Ltd, India in Marketing department. I have 20 years of experience in the field of submersible bore hole pumps and submersible sewage pumps. My experience includes Research & Development for two years, design 7 years, projects 5 years and now looking after Projects in marketing department. In addition, I am excellent in the field of testing of motors, designing of instrument panels ( for performance testing )and control panels.
I hope this will be useful for you.
Rajendra Joshi
So if you have any problem like the one here, you ask and I will try to find a solution on it.
- Thread starter
- #8
Some very good tips have been given such as the one from
AARVEEJE.My question with its use has to do with that stator coil also known as "flux coil" which may indicate slip is problematic.We even considered using that for non-submerged motors but did not pursuit.The system is intrusive,complex and if the only thing you need is an RPM signal,I can't see anything much simpler than a "GAP probe " or Prox Probe.Easy to install, even for a submerged application,reasonably cheap and accurate.2 wires output pulses that can be easely converted to V/mV/or mAs .
Thank you. GusD
AARVEEJE.My question with its use has to do with that stator coil also known as "flux coil" which may indicate slip is problematic.We even considered using that for non-submerged motors but did not pursuit.The system is intrusive,complex and if the only thing you need is an RPM signal,I can't see anything much simpler than a "GAP probe " or Prox Probe.Easy to install, even for a submerged application,reasonably cheap and accurate.2 wires output pulses that can be easely converted to V/mV/or mAs .
Thank you. GusD
- Thread starter
- #12
- Thread starter
- #13
Dear Rajeendra Joshi,
I would be gratefull for details of this Slip Coil .
Typical motor....Eg Hitachi Plueger Franklin 8" 100hp
Continous rating
Voltage 415
Frequency 50 hz
OD 8" 200mm
Lamination iron length 31.9" 800mm
Rotor Aluminium or copper bars
Please ask for any further information required.
Regards Alan.
I would be gratefull for details of this Slip Coil .
Typical motor....Eg Hitachi Plueger Franklin 8" 100hp
Continous rating
Voltage 415
Frequency 50 hz
OD 8" 200mm
Lamination iron length 31.9" 800mm
Rotor Aluminium or copper bars
Please ask for any further information required.
Regards Alan.
- Thread starter
- #14
Dear GusD,
Can you steer me towards obtaining details on the Gap Probe or Proximity Probe.
What physical size are these?
Can they operate in a water filled motor?
Room available is very very restricted,in some cases less than half inch diameter one -two inches long,ie they have to fit into the crown of the winding with the internal cable joins / splices.
I like the simple two wire signal idea,as this is what is required to bring to the surface control box.
Thanks Gus,
Regards Alan......
Can you steer me towards obtaining details on the Gap Probe or Proximity Probe.
What physical size are these?
Can they operate in a water filled motor?
Room available is very very restricted,in some cases less than half inch diameter one -two inches long,ie they have to fit into the crown of the winding with the internal cable joins / splices.
I like the simple two wire signal idea,as this is what is required to bring to the surface control box.
Thanks Gus,
Regards Alan......
Hi grover
Trying to follow up on your GAP probe question.
Try this sight.They should have all you need for your
particular application
GusD
Trying to follow up on your GAP probe question.
Try this sight.They should have all you need for your
particular application
GusD
Dear Mr. Grover,
I am unable to attach the file to this message, which gives the construction of slip coil and method of measurement of speed. Please mail me on " rvjoshi@ksb.co.in " so that I can send it by mail.
Regards,
Rajendra
I am unable to attach the file to this message, which gives the construction of slip coil and method of measurement of speed. Please mail me on " rvjoshi@ksb.co.in " so that I can send it by mail.
Regards,
Rajendra
- Thread starter
- #19
JOmega, And GusD,
Hi, The pumps are multi stage centrifugal type,can be up to 20 plus stages ,or impellers.
Regarding accesability to the shaft, internally the shaft in most subm motors is "covered" by the snout or bearing mount,most have carbon guide bearings that extend almost to the laminations,on both the drive and non drive end.This makes it not possible to have access to the bear shaft.
The internal room in the connection area is very restricted,and only allows enough room for the 3( in most cases )internal leads.Hence installing a device in the crown area is not a option.
Please keep up the discussion
......Grover ( Not From Sesame Street ).....
Hi, The pumps are multi stage centrifugal type,can be up to 20 plus stages ,or impellers.
Regarding accesability to the shaft, internally the shaft in most subm motors is "covered" by the snout or bearing mount,most have carbon guide bearings that extend almost to the laminations,on both the drive and non drive end.This makes it not possible to have access to the bear shaft.
The internal room in the connection area is very restricted,and only allows enough room for the 3( in most cases )internal leads.Hence installing a device in the crown area is not a option.
Please keep up the discussion
......Grover ( Not From Sesame Street ).....
I don't know what type of submersible pump you have.It may or may not be an easy task to adapt a gap/prox probe unless you have access to at least 1/2" of shaft showing.
If you just want to take a spot measurement of pump speed at full load to verify slip,I would wait for a time when you have highest load and do a current measurement.
Your Pump curve should give you a fairly good indication of what you have.The probes I suggested would be for a continuous speed measurement. GusD
If you just want to take a spot measurement of pump speed at full load to verify slip,I would wait for a time when you have highest load and do a current measurement.
Your Pump curve should give you a fairly good indication of what you have.The probes I suggested would be for a continuous speed measurement. GusD
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