Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.

Higher than Line Voltage Voltage!

Start and run windings are in intimate contact with each other inside the shell of the motor. When voltage is applied to the motor and current flows through the start and the run winding, an induced voltage is generated. This is the same concept that facilitates the operation of transformers. At any rate, the current flow through the run winding induces a voltage across the start winding. So, when you take a voltage reading across the start winding, your reading will be higher than the line voltage.

This is the same exact concept on which the potential magnetic relay operates.

Comments

  • Techman
    Techman Member Posts: 2,144
    Potential Relay Voltages

    Hi All!Professor,On 1ph compressors the voltage reading[ on a running unit]on the" C to S "terminals is always higher than "line voltage".What is this higher voltage called?Does this happen on 3ph units ?
  • Techman
    Techman Member Posts: 2,144


    > Start and run windings are in intimate contact

    > with each other inside the shell of the motor.

    > When voltage is applied to the motor and current

    > flows through the start and the run winding, an

    > induced voltage is generated. This is the same

    > concept that facilitates the operation of

    > transformers. At any rate, the current flow

    > through the run winding induces a voltage across

    > the start winding. So, when you take a voltage

    > reading across the start winding, your reading

    > will be higher than the line voltage.

    >

    > This is

    > the same exact concept on which the potential

    > magnetic relay operates.



  • Techman
    Techman Member Posts: 2,144
    Higher Volts!

    Thank You ,does this "higher voltage have a name?Saying "higher than line voltage voltage" tends to get stuck in conversation,especially, with electricians,and apprentices. Thanks ,again.
  • Paul Fredricks_3
    Paul Fredricks_3 Member Posts: 1,549


    When I was in school, a hundred years ago, we called it Back EMF (EMF is electro-motive force). This voltage is used to trigger the start relay to take the start capacitor out of the loop.
  • Techman
    Techman Member Posts: 2,144
    Back EMF

    HI Paul,That is what I've called it for Years but in the past 8-10 months some college electrical engineering students have said "NO WAY-OLDTIMER". So ,what is the proper term ?[YOU YOUNG WHIPPERSNAPPER!].GOOD DAY!
  • Paul Fredricks_3
    Paul Fredricks_3 Member Posts: 1,549


    They wanted you to stew awhile before they told you? I have no idea. Back EMF works for me. How about winding induced voltage? Or magnetic voltage transferance (I'm making this up, but it could be).

    Or Wattage Heat Amperage Transfer Energy Vector Electric Replacement, also known as WHATEVER.
  • Eugene Silberstein
    Eugene Silberstein Member Posts: 1,380
    It's Induced Voltage

    I though I mentioned that earlier.

    Oh well..

    I do like the WHATEVER idea, though.
  • bob_50
    bob_50 Member Posts: 306
    Techman

    Tell the young whippersnapper to put one finger on C and another on S while it's running and let HIM tell you what it is.
  • jim lockard
    jim lockard Member Posts: 1,059
    All wrong

    you put (C) Common on his tongue and (S) Start in his ear and ask him to shake his head when the compressor starts. Best Wishes J.Lockard
This discussion has been closed.

Welcome

It looks like you're new here. If you want to get involved, click one of these buttons!