cordova64
Member
- Location
- Vancouver Washington
Can you apply a 60hz supply to a 50 hz motor?
50 Hz motor on a 60 Hz supply
- Thread starter cordova64
- Start date
- Status
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
080419-1240 EST USA
Yes.
Assuming the input voltage for 60 Hz is about 6/5 of the 50 Hz voltage the performance will be about the same except speed and power output rating will be 6/5 times the 50 Hz values, and core and windage losses will be somewhat higher.
This does not address the problems of the higher speed for the load.
.
Yes.
Assuming the input voltage for 60 Hz is about 6/5 of the 50 Hz voltage the performance will be about the same except speed and power output rating will be 6/5 times the 50 Hz values, and core and windage losses will be somewhat higher.
This does not address the problems of the higher speed for the load.
.
cordova64
Member
- Location
- Vancouver Washington
Thank you for your reply. I have a motor that is coming from germany and it runs on 50 hz. I still have to verify the voltage.
L
Lxnxjxhx
Guest
power output rating will be 6/5 times the 50 Hz values
power output rating will be 6/5 times the 50 Hz values
Why and how?
I'd think going either above or below 50 Hz should decrease performance.
power output rating will be 6/5 times the 50 Hz values
Why and how?
I'd think going either above or below 50 Hz should decrease performance.
- Location
- Massachusetts
I can tell you it is very common to run 50 hz motors on 60 hz.
As has been mentioned consider how the speed increase will effect the driven equipment.
As has been mentioned consider how the speed increase will effect the driven equipment.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
080419-1605 EST USA
Lxnxjxhx:
Core losses increase with frequency. Eddy current losses are related to core resistance and thinner laminations reduce this loss. To the extreme you go to powdered metal to reduce these losses. Hystersis losses depend upon the type of material. Inter-related is the I squared R loss from current to supply the core losses.
If you raise the voltage in proportion to the frequency, then the peak flux level is the same.
Output torque is proportional to current. Power is proportional to Speed * Torque. Speed will increase by 6/5 and the motor rating is largely dependent upon I squared R losses. So if current remains constant and speed increases, then more power.
.
Lxnxjxhx:
Core losses increase with frequency. Eddy current losses are related to core resistance and thinner laminations reduce this loss. To the extreme you go to powdered metal to reduce these losses. Hystersis losses depend upon the type of material. Inter-related is the I squared R loss from current to supply the core losses.
If you raise the voltage in proportion to the frequency, then the peak flux level is the same.
Output torque is proportional to current. Power is proportional to Speed * Torque. Speed will increase by 6/5 and the motor rating is largely dependent upon I squared R losses. So if current remains constant and speed increases, then more power.
.
L
Lxnxjxhx
Guest
6/5
6/5
You guys may all be right, but with the equivalent circuits of motors that I've seen I can't quite get to 6/5. Same voltage, but raise the freq., right? Nameplate says 50 Hz?
Can you give a qualitative reference or math derivation?
Also, what bugs me is that, just from an economic point of view it pays to optimize a motor's performance at the freq. that it will work at.
An audio transformer has a wide but limited bandwidth. Even if a motor's "bandwidth" is flat over some moderate range, it still wouldn't work better while operating away from the design-center freq., whatever that freq is.
6/5
You guys may all be right, but with the equivalent circuits of motors that I've seen I can't quite get to 6/5. Same voltage, but raise the freq., right? Nameplate says 50 Hz?
Can you give a qualitative reference or math derivation?
Also, what bugs me is that, just from an economic point of view it pays to optimize a motor's performance at the freq. that it will work at.
An audio transformer has a wide but limited bandwidth. Even if a motor's "bandwidth" is flat over some moderate range, it still wouldn't work better while operating away from the design-center freq., whatever that freq is.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
080419-1905 EST USA
Lxnxjxhx:
Here is an old reference, but the basics do not change. There are really a number of prerequisites needed to be able to understand this text. It also helps if you have a true teacher for the course. Mine was Dr. J. G. Tarboux who had a very intitutive technique.
"Alternating-Current Machinery" by Bailey and Gault, McGraw-Hill, 1951.
Someday I need to do a search on the basic patents on electrolytic capacitors, but hearsay information from a person that helped run early tests on these capacitors indicated that Gault was the inventor of this type capacitor or at least a major player in its early development. This would date to the very late 20s or early 30s. In 1928 radios did not use electrolytic capacitors, but by the mid 30s these were common.
.
Lxnxjxhx:
Here is an old reference, but the basics do not change. There are really a number of prerequisites needed to be able to understand this text. It also helps if you have a true teacher for the course. Mine was Dr. J. G. Tarboux who had a very intitutive technique.
"Alternating-Current Machinery" by Bailey and Gault, McGraw-Hill, 1951.
Someday I need to do a search on the basic patents on electrolytic capacitors, but hearsay information from a person that helped run early tests on these capacitors indicated that Gault was the inventor of this type capacitor or at least a major player in its early development. This would date to the very late 20s or early 30s. In 1928 radios did not use electrolytic capacitors, but by the mid 30s these were common.
.
L
Lxnxjxhx
Guest
Bailey and Gault, Tarboux
Bailey and Gault, Tarboux
I found all these guys on the Internet.
I'll try to borrow the book on Interlibrary loan. Probably the University of Maryland's Engineering library would have it. With luck, I'll have it in a few weeks.
Better yet, do you have the book?
Do you have a scanner?
All I need is to see one equation that references a linear relationship between frequency, speed and power output when running a 50 Hz motor on 60 Hz. I can go from there.
By the way, what type of motor construction are you assuming?
Bailey and Gault, Tarboux
I found all these guys on the Internet.
I'll try to borrow the book on Interlibrary loan. Probably the University of Maryland's Engineering library would have it. With luck, I'll have it in a few weeks.
Better yet, do you have the book?
Do you have a scanner?
All I need is to see one equation that references a linear relationship between frequency, speed and power output when running a 50 Hz motor on 60 Hz. I can go from there.
By the way, what type of motor construction are you assuming?
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Actually that is technically correct, but usually the voltage is NOT the same. Most 50Hzmotors from Germany are going to be rated 400V (or 380V if it is older). If you consider the flux density can be boiled down to a ratio of V to Hz, then as long as the ratio remains the same, it will work the same (as gar already said). So if you have a 400V 50Hz motor, the ratio is 8:1. If you supply 480V 60Hz to it, the ratio is still 8:1, so it works fine, same torque just 20% faster. Since HP = Tq x RPM / 5250, then the higher RPM with the same Tq means higher HP.Lxnxjxhx said:
cordova64
Member
- Location
- Vancouver Washington
Thanks for the replies. It was very useful. Sounds like if the motor from germany is 400v @ 50hz. Then applying 480v @ 60 hz would be fine. With a HP increase of 20%
cadpoint
Senior Member
- Location
- Durham, NC
- Occupation
- Electrician - but not by NC Law.
Why not get a VFD? Not so much thats its a prized motor from Germany, but you have to deal with the German that comes to check your install.
I'd shoot a second flair.
I will note that you also throw in the bulk flux statement, I understand it I just don't like that thought.
I want to agree but also disagree with your 8 to 1 ratio, freestyle application. Alot of thoughts come to mind, type of flux wiring being the key. How they get to that rating is to each manufacturers descrection.
They could go heavy gauge wire they could have used lower gauge.
Or is this motor so none specific it doesn't matter! I won't want to apply this application, some one else can get involved and show me something else, before I would.
I'd shoot a second flair.
I will note that you also throw in the bulk flux statement, I understand it I just don't like that thought.
I want to agree but also disagree with your 8 to 1 ratio, freestyle application. Alot of thoughts come to mind, type of flux wiring being the key. How they get to that rating is to each manufacturers descrection.
They could go heavy gauge wire they could have used lower gauge.
Or is this motor so none specific it doesn't matter! I won't want to apply this application, some one else can get involved and show me something else, before I would.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
080421-0603 EST USA
Lxnxjxhx:
On p 5-7 of Bailey & Gault is a transformer discussion on flux and excitation voltage. Note: in the example the peak flux density is below significant saturation for the curve on p 7.
A low resistance rotor induction motor runs close to synchronous speed for normal loads. A synchronous motor runs at synchronous speed with a shaft phase angle shift as load increases.
Synchronous speed is proportional to frequency.
Torque is proportional to current.
AC motors called Universal are a totally different story. DC brushless motors are really a permanent magnet synchronous motor with additional circuitry.
See Bailey & Gault or others or the Internet for verification of this information.
.
Lxnxjxhx:
On p 5-7 of Bailey & Gault is a transformer discussion on flux and excitation voltage. Note: in the example the peak flux density is below significant saturation for the curve on p 7.
A low resistance rotor induction motor runs close to synchronous speed for normal loads. A synchronous motor runs at synchronous speed with a shaft phase angle shift as load increases.
Synchronous speed is proportional to frequency.
Torque is proportional to current.
AC motors called Universal are a totally different story. DC brushless motors are really a permanent magnet synchronous motor with additional circuitry.
See Bailey & Gault or others or the Internet for verification of this information.
.
GeorgeB
ElectroHydraulics engineer (retired)
- Location
- Greenville SC
- Occupation
- Retired
iwire gave very good information ... the MOTOR will likely be fine, but may run a little hotter as the iron isn't optimized for 60 Hz. we talk about maintining the "volts per Hertz ratio". You will see that most inverters do that as their most basic control criteria.cordova64 said:
Your LOAD determines if the application is ok. I'd NOT count on getting 1.2* the power ... 1.1 maybe. The motor cooling is probably not up to it.
If you are running a hydraulic pump, your load will increase linearly with speed; these USUALLY work ok. If you are driving a fan, these increase as the cube of the speed ... so that 1.2^3 suggests ~170% power required. These usually DO NOT work ok. Perhaps some are not speed sensitive ... cartainly ok. Most will likely be between linear and cube ... you need to evaluate.
You had another comment that an inverter is good ... and if it is a speed sensitive load, that is a very reasonable approach.
Running a 60Hz motor from a 50Hz supply.
Running a 60Hz motor from a 50Hz supply.
Excuse my ignorance in advance - I'm not an electrical engineer, just a mere project engineer.
We have purchased a Sumitomo motor from Japan rated at 18.5kWx4Px440Vx 60Hz. We will be using this in India where the supply will be 415Vx50Hz, though it will be operate from a 6-60Hz VVVF.
Will there be any issues with performance of the motor (speed, torque etc.)?
Any advice is most welcome.
Running a 60Hz motor from a 50Hz supply.
Excuse my ignorance in advance - I'm not an electrical engineer, just a mere project engineer.
We have purchased a Sumitomo motor from Japan rated at 18.5kWx4Px440Vx 60Hz. We will be using this in India where the supply will be 415Vx50Hz, though it will be operate from a 6-60Hz VVVF.
Will there be any issues with performance of the motor (speed, torque etc.)?
Any advice is most welcome.
weressl
Esteemed Member
gavjem said:
Of course there will be.
If the motor nameplate does not list other voltages and frequencies it should not be used for anything outside of the listed rating if you wish to remain Code compliant. The motor should not be used with an ASD if it is not specifically designed for such use.
I think others have approriately elaborated on the effects of voltage and frequency change effects on a motor, so I will not add to taht discussion. The shaft circulating current, however, was not mentioned and it can be damagning to the bearings.
Should you wish to step outside the nameplate operating parameters, installing a 'trap' at the motors orr output reactor on the ASD will help. Follow the ASD manufacturer's instructions on the cable length. If you have temperature detectors on the winding, Thermistors or RTD's, it will help you with the thermal life of the motor. Lastly keeping the motor to a 10:1 speed turndown ratio is advisable for variable torque loads.
- Status