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.
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
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.
-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.
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 (^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?
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.
Posted via a free Usenet account from http://www.teranews.com
The magnetic field in the steel has to stay below a value (the
in order for the motor not to burn up. That limit roughly tracks (is
to) the voltage divided by the frequency. Lower frequency (like 50 Hz)
lower voltage for any given copper/iron winding.
There are also dependencies in the capacitor values, if the motor has
Okay, so I'm late and catching up, but email@example.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
I wonder where I could find out ...
as an explaination for the decline in the US's tech edge, James
On Wed, 08 Nov 2006 11:30:22 GMT, 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
Posted via a free Usenet account from http://www.teranews.com
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
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