what is the diff between 50hz and 60hz

Just as the title asks, I need someone to explain in laymans terms what
the difference is on 50Hz and 60 Hz motors... and with a suitably sized
VFD, can a person use the 50Hz motor without problems with 220Volt
single phase 60Hz input?
thanks,
ron
Reply to
rbce2003
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With motors and transformers, the flux level in the iron depends on the voltage applied and the time the voltage is applied. So a 50 hz motor is designed for a higher E x T than a 60 hzs motor ( a cycle is longer for the 50 hz , therefore the T is bigger ) The difference is not huge and most motors will work on either 50 or 60 hz.
You should have no problem running a 50 hz motor using a VFD regardless of the frequency of the power input to the VFD.
Dan
Reply to
dcaster
Thanks Dan!
Another spin on this question... if the HP rating is 15 @ 50 Hz, would it be higher at 60Hz? I was told this from a fellow that sells surplus electrical equipment,
thanks, ron
Reply to
rbce2003
Trivially so
but that is part of how the big VFD's work too
but the motor will be running at 20% overspeed from its design
also of note is that a lot of equipment uses the hydro company line frequency (Which has to be very accurate) as an inbound clock via frequency division (if you take the inbound frequency and divide it by 50 or 60 in a control circuit you have a very accurate counter of one second (Depending on the place) running a 50hz time aware device on 60Hz will make the clock count 20% faster. Doing the opposite (running a 60Hz device at 50 will make it 18% slower)
Transformers LIKE higher input frequencies universally the higher the frequency the less loss a transfrmer has the cooler it runs and the SMALLER it has to be to pass a given amount of power. THats part of the reason Aviation uses i think 400Hz as its AC frequency
it requires transformers whicha re much smaller to do the same work.
The only issue with running a 50Hz motor at 60 Hz is the mechanical sections have to be able to withstand turning 20% faster
Most do not have an issue as most motors are rated at a certain RPM at 50 and a certain one at 60
snipped-for-privacy@hotmail.com wrote:
Reply to
Brent
Two differences: 50 Hz motors will have a lower nominal nameplate speed (e.g. 1450) as opposed to 60 Hz motors (e.g. 1760 rpm). Also, any 50 Hz motor will run fine on 60 Hz power, but the reverse is not always true. I believe 50Hz motors have more copper in them, so should cost more than the equivalent 60Hz motor.
I don't know for sure, but if it were my choice to make, I'd confidently use a 50Hz motor on a 60Hz system with a VFD.
Grant
Reply to
Grant Erwin
Yes!
Provided that:
-The VFD is rated to run on the input voltage available, -The VFD outputs suitable voltage for the motor to be run,
It will work fine.
As mentioned in another post, you may wish to check what rpm the blower can deal with.
Somewhere in your manual it should detail setting up the range of speed you want available. You should be able to program limits. Of the few VFDs I have been around, some displayed the output as a percentage of input frequency (60Htz @ 100%, 50 Htz would be 83%), some displayed the output in (IIRC) Htz directly, and one of the lathes at work has a direct readout of the RPM, but I think that is separate from the VFD on it. Check the book of words for programming instructions.
Cheers Trevor Jones
Reply to
Trevor Jones
You can run a 50 Hz motor fine on 60 Hz. The 50 Hz motor has more steel and copper to handle the lower frequency without magnetic saturation, so it will be more efficient on 60 Hz and you can draw more than rated power from it. Regard it as a 60 Hz motor rated at 1.2 times its rated horsepower.
If you are using it on a machine designed for a 60 Hz motor, the MOTOR will be fine with no special attention whatsoever PROVIDED the machine does not overload the motor due to increased speed. If you are driving a speed-sensitive machine like a blower designed for a 50 Hz motor, you may run into an overspeed or overload situation requiring a change in sheave size or tweaking down the VFD. The power demanded by a fan increases with the cube of speed ({60/50}^3=1.72), which is a more rapid increase than the increased power available from the 50 Hz motor driven at 60 Hz (I'm guessing 1.2 times rated). The capacity (amount of air moved) of a fan increases directly with speed, so running it at excessive speed is a big energy waste.
What are you driving?
awright
Reply to
Anne Irving
If you are running it off a VFD, why not just run it at 50 Hz?
Reply to
ATP*
All good points, thanks to each of you!
I will bid on the pump and will report back what happens!
ron
Reply to
rbce2003
The magnetic field in the steel has to stay below a value (the saturation limit) in order for the motor not to burn up. That limit roughly tracks (is proportional to) the voltage divided by the frequency. Lower frequency (like 50 Hz) requires lower voltage for any given copper/iron winding.
There are also dependencies in the capacitor values, if the motor has those.
Reply to
whit3rd
Okay, so I'm late and catching up, but snipped-for-privacy@hotmail.com wrote on 7 Nov 2006 09:02:47 -0800 in rec.crafts.metalworking :
You might be able too do so, but any thing which is time dependent is going to be off. The motor may handle the difference in speeds, but the application may not. "If you care." (I doubt that you are going to be using a 50 Hz motor to drive a turntable at 60 Hz.)
Hmmm, I wonder if there is a difference between 50hz CD players, and 60hz?
I wonder where I could find out ...
pyotr
Reply to
pyotr filipivich
If you think CD players rely on the power source for frequency, you're mistaken. Most run on DC anyway.
GWE
Reply to
Grant Erwin
Motors are designed to run at a particular magnetic flux density which is quite a bit less than magnetic saturation level. Higher than normal flux density increases the iron losses so the motor runs hotter.
Flux density is proportional to volts divided by frequency.
Maximum torque is proportional to flux density
Motor RPM is proportional to frequency.
Motor HP is proportional to RPM times torque
***
So for a 50 Hz motor on the SAME voltage at 60Hz
RPM is 60/50 = x 1.2
Flux density is 50/60 = x 1/1.2 = x 0.83 Flux density is reduced so motor runs cooler
HP is 1.2 x 1/1.2 = x 1.0 - NO change
THe motor voltage could be increased by x 1.2 to restore the original flux density and torque. HP would then be x 1.2
***
For a 60 Hz motor on the SAME voltage at 50 Hz
RPM is 50/60 = x 1/1.2 = x 0.83
Flux density is 60/50 = x 1.2 Flux density is increased so motor runs hotter
HP is 1/1.2 x1.2 = 1.0 - NO change
***
On most loads, provided a motor is running comfortably within its normal maximum ratings, either type of motor can be used on either frequency without problem.
However, fan loads are a different case. A fully loaded 50Hz fan operating on 60hz is severely overloaded.
The output frequency of a VFD is independent of the local supply frequency. Although they are normally supplied set up to give the correct output for local supply frequency motors these settings can be altered.
Different manufacturers have their own name for this - usually called "Maximum Voltage Frequency" or "Base Frequency". If this parameter is set to the the non standard motor frequency the VFD will automatically deliver the correct output.
Jim
Reply to
pentagrid
Okay, so I'm late and catching up, but Grant Erwin wrote on Wed, 08 Nov 2006 04:44:35 -0800 in rec.crafts.metalwork>
Thanks. I didn't know, just extrapolating from turn tables.
tschus pyotr
Reply to
pyotr filipivich
Generally not, as they run what is basically a fixed frequency VFD, usually controlled by a crystal timebase and/or phase lock loop system to run the brushless DC servo motor at the correct speed (which, on a CD or DVD, varies depending on where on the disk the head is reading, as it is a constant linear velocity system, not a constant rotational velocity.
Reply to
clare at snyder.on.ca
According to :
And the CD drive reads ahead of the actual point being played, loading into a buffer, and it is played from the buffer instead, so the speed of the CD-ROM is not critical -- as long as it is fast *enough*.
Those for joggers run larger buffers so the thing has a reasonable chance to find its place before the buffer empties if the head is bounced out of position by the bumps of jogging.
And the CD-ROM drives for computers make use of much higher speeds, since the computer *can* listen at higher rates when data is being loaded.
Enjoy, DoN.
Reply to
DoN. Nichols

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