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Registered Member #9252
Joined: Fri Jan 04 2013, 06:27AM
Location: Andromeda
Posts: 253
I have around 225 - 240 volts. Would removing the shunts and adding 60 turns of 12 guage wire to the primary take the MOT out of saturation. Do note that it is fairly powerful (Came out of a 3KW oven)
Registered Member #72
Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
Removing the shunts will do nothing for saturation, however it's needed to give you the space for the extra primary turns. If these extra turns are connected in the correct phase, then that will take you out of saturation.
Unless ... you have a 120v MOT. What is the mains voltage for oven MOTs on Andromeda?
Registered Member #9349
Joined: Mon Jan 07 2013, 08:50AM
Location: France
Posts: 102
Hi !
I experimented with that, but i went to another way. It was mainly for a low voltage application :
I removed two mots secondary, then i disassembled two mots and kept the two E cores, then i welded them together. That way, i had two mots primary for the same iron area, and plenty of room for wiring a new low voltage secondary. I wired the two primaries in series so that each of them would only see half of my 240v line. In other words, the new transformer had double primary turn per volt ratio.
As a result, the transformer was out of saturation, and could run 24/24 without overheating the primary. The magnetizing current was also pretty low.
Registered Member #72
Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
StormInABottle wrote ...
240 volt mots. How can I make sure they are connected in the right phase? I bet the mot will be much more efficient.
If you have a suitable source of low voltage AC, then energise any of the windings, and measure the voltage across your new composite primary. Reverse the phase of the additional winding and measure again. Choose the phasing that gives the highest voltage.
If you don't have a low voltage AC source, then just energise the original primary from the mains. Measure the result carefully because you are now on the mains side! Don't experimentally energise the new composite primary first off as, if the phasing is wrong, you may take out fuses or breakers.
Registered Member #1232
Joined: Wed Jan 16 2008, 10:53PM
Location: Doon tha Toon!
Posts: 881
If you have a generator available you can also reduce the volt-second product by increasing the frequency. That will have a similar "saturation reducing" effect as adding more turns to the primary or reducing the primary drive voltage, but without reducing the HV output from the secondary.
Registered Member #3343
Joined: Thu Oct 21 2010, 04:06PM
Location: Toronto
Posts: 311
I am in fully agreement with Dr Slack. Follow his recommendations.
When I need to phase a MOT primaries I use to apply 230V on the secondary. Then I measure voltage at the normal factory primary and the voltage at the new primary coil. Normally I get the following primary voltages: Normal Factory Primary Coil= 24V New Primary Coil (60 turns) = 6V When connecting the primaries in series I can get the following voltages: a - 18V (this connetion will saturate MORE YET the core) - avoid it. b - 30V, (this connection will reduce the core "saturation" ) - use this connectiion.
One lead of the secondary coil is factory connected to the core, so whem applying 230 or 110 V to the secondary the core will be enegized with the line voltage. Be carefull toching the core, the core is hot with 120 or 230 volts.
Gauge #12 for the new primary coil will works fine, but appears to be litle oversize - what is the factory primary gauge ? Copper or Aluminum ?? The new primary coil may follow the same gauge (or less) that the factory coil.
What is the purpose for such MOT ??? Give us more information
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Taking a MOT out of saturation
