Unfortuneately no VFD will drive a single-phase motor, only 3ph motor loads.
Depends on the contruction of the motor, but outside of a suitable audio power amplifier with a transformer (filament transformers work well, ‘reversed’) to match the motor impedance,
there’s no slick way of reducing induction motor speed and maintaining frequency accuracy otherwise. I’ve used this scheme for 400htz motors. And of course there are lots of ‘bench’ supplies for variable frequency, 50 – 100 – 200W and up, 1 and/or 3ph – but
they are not cheap, even on That Auction Site.
I do industrial and aerospace control systems as a business, and this exact subject comes up from time to time. And trust me, we’ve tried. Got the bloody t-shirts to prove it.
There are companies who make specialized speed-accurate drives for 1ph motors, but they’re in the US$2K range and up. We just installed a 75HP 600V DC motor controller for a 15,000
rpm pump test bench. It was north of US$30K.
Many sync motors (60htz) will run on 50 htz, but the heat disspation goes up. If the motor is not running at its torque limits, you might get away with 50 htz and suitable gears.
FYI I have 2 Teletype (GE) 50 htz motors NOS, dual-shaft, model 15/19 perhaps. No one here in the US loves them, and shipping to 50Htz lands is too pricey.
Cheerz
John KB6SCO
Carson City NV
Consider a small Variable Frequency Drive. Most can be set wherever you like for voltage and frequency, many will accept a single phase power input and load.
Brenda Gentry
On 9/3/26 2:26 PM, Malcolm Macleod via GreenKeys wrote:
Greetings all.
I have a 115V/60Hz Model 28 KSR that I imported to Australia some years
back. My aim is to get this working on our local mains supply (230V 50Hz).
I'm happy to use a 230V/115V stepdown transformer if needed. The bigger
issue is the change in mains frequency, and possibly gear change if the new
motor speed is 3000RPM (rather than 3600RPM).
Wondering if anyone can help with a suggestion as to which motor(s) and/or
gear sets I should be looking for.
The main resource I've been looking at is Teletype Corp bulletin 295B
(particularly page 67) ->
https://www.navy-radio.com/manuals/tty/295B-7012.pdf
Option 1: Am I able to run the existing 60Hz synchronous motor at 50Hz and
just change the gear set to accommodate the reduced RPM? If so, what gear
set do I need for 45.4Bd/60WPM at 3000RPM? I remember trying this a decade
ago on an ASR33 and it wasn't successful due to excessive heating of the
motor.
Option 2: Might I be able to run a 115V/60Hz 3600RPM series governed motor
on 50Hz? If so, it seems I should be looking for an LMU4, LMU6, LMU41,
LMU57 or LMU61. If it's acceptable to use an ASR motor in the KSR, then the
additional options (for 115V/60Hz) seem to be LMU14, LMU39 or LMU61.
Option 3: If it's not OK to run a 60Hz series governed motor at 50Hz, then
the 115V/50Hz options seem to be LMU38 or LMU50, though these will run at
3000RPM.
Option 4: I would also be fine of course with an LMU55 (230V/50Hz), though I
don't think I will be lucky enough to find one of these, and a gear change
would be necessary as well.
Option 5: Another alternative seems to be an LMU29 (Series governed
48V/3600RPM).
If you have any of these motors that you might be willing to sell, or
otherwise can shed some light in how to solve this problem, please let me
know. I'm in the U.S. for the next couple of weeks, so can easily take one
back with me if there's one available there. Similarly interested in
anything that might be available in Australia or the U.K. for local
shipping.
______________________________________________________________
GreenKeys mailing list
Home: http://mailman.qth.net/mailman/listinfo/greenkeys
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[email protected]
Jordan Spencer Cunningham's GreenKeys Search Tool: https://teletype.net/gksearch
2002-to-present greenkeys archive: http://mailman.qth.net/pipermail/greenkeys/
1998-to-2001 greenkeys archive: http://mailman.qth.net/archive/greenkeys/greenkeys.html
Randy Guttery's 2001-to-2009 GreenKeys Search Tool: http://comcents.com/tty/greenkeyssearch.html
This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [email protected]