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reactor purpose for variable speed motor

Does anyone know the purpose of the inline reactor (looks like a transformer) when it is installed on a variable speed blower motor? Normally I see these installed on 1 hp motors and I was wondering it's purpose, and would it be the same part for a 16 pin variable speed motor (2.3) , as it would be for an X13 motor? Thanks to all


  • Jamie Hall
    Jamie Hall Member Posts: 23,322
    Kind of a guess -- but I would guess that it is there to choke high frequency switching harmonics from the motor so they don't get back into the power line. Anything which uses a switching power supply or uses switching for speed control -- like you motor -- generates a lot of very high frequency hash, and if that gets into the power line it creates all sorts of problems for other equipment on the same electrical drop from the power company.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    JUGHNE Member Posts: 11,062
    In addition to furnace blower motors, every Mini Split inverter has one also.....anyway the ones do that I have had the misfortune to have to trouble shoot :(

    Easiest ones are a shorted compressor...new system time after 13 years.
  • ratio
    ratio Member Posts: 3,627
    Load reactors are a thing too.

    Also mind that a 'rotary' compressor is not a 3 phase compressor. It's basically a giant BLDC motor, with a permanent magnet armature. The controller pulses the windings on & off—and reverses the magnetic polarity—to move the armature. They can not be reversed by swapping leads, or at least the ones I've come across can't.