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Fan motor

  • 07-07-2012 8:50pm
    #1
    maxamillius
    Registered Users, Registered Users 2 Posts: 1,136 ✭✭✭


    Hi lads,work in maintenance,came across a strange one the other day,was replacing a fan coil unit in a room

    The fan itself has 6 speeds we only use three of them though,from the stat 3 speeds are connected to 3 relays which in turn output 230 volts to corresponding speeds,

    All is as it should be until I connect the motor to the speeds coming from relays,all 6 speeds from the motor show 320 volts very strange,any ideas??

    It's a mind boggler,thought it might be a nice discussion though!!


Comments

  • #2
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    maxamillius wrote: »
    Hi lads,work in maintenance,came across a strange one the other day,was replacing a fan coil unit in a room

    The fan itself has 6 speeds we only use three of them though,from the stat 3 speeds are connected to 3 relays which in turn output 230 volts to corresponding speeds,

    All is as it should be until I connect the motor to the speeds coming from relays,all 6 speeds from the motor show 320 volts very strange,any ideas??

    It's a mind boggler,thought it might be a nice discussion though!!

    Is this when the motor is running? Is it running properly, but you are wondering why 320v?


  • #3
    maxamillius
    Registered Users, Registered Users 2 Posts: 1,136 ✭✭✭maxamillius


    yep when the motor is running robbie,all speeds show voltage on it whereas it should only be three speeds showing 230v,motor still runs properly but something aint right!


  • #4
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    maxamillius wrote: »
    yep when the motor is running robbie,all speeds show voltage on it whereas it should only be three speeds showing 230v,motor still runs properly but something aint right!

    Id say its probably voltage being generated in the open circuit unused windings by the motor rotating.

    Of you only connect live and neutral to 2 of the 3 connections of a 3 phase motor for example, and give it a push start, the third connection point will have a 3rd phase on it (relative to live and neutral) when the motor runs up to speed, generated by the motor spinning.


  • #5
    maxamillius
    Registered Users, Registered Users 2 Posts: 1,136 ✭✭✭maxamillius


    Ye that does sound about right mate,thought it might be some sort of leakage,why would it not show 230 on them though,must check one of the other rooms when I'm back next week and see does it output same v on the unused speeds!

    It's not causing a problem just had not come across it before!!although now I think of it I think that motor is only running with 1 speed it's not getting any higher or lower but that could be a problem with the stat!!


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