Design a lock rotor protection circuit for high voltage high current DC motor

Discussion in 'Electronic Design' started by GoGo~, Apr 20, 2005.

  1. GoGo~

    GoGo~ Guest

    I have a 240Vdc DC motor with normal working current is 4A. For the
    motor's rotor locking, its current will drive to 40A. So, I suppose to
    design a external circuit for regarding motor.

    It is a lock rotor circuit: when motor has been locked, the external
    circuit can be detected the motor's rotor. If it is rotor locking, the
    main input source will be cut off.

    May I know how to design such kind of circuit? Because it is in high
    voltage high current, is it not easy to use some voltage comparators
    for current sensing? Any detail information can be shared?

    Thanks~
    GoGo~, Apr 20, 2005
    #1
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  2. "GoGo~" <> wrote in message
    news:...

    > May I know how to design such kind of circuit? Because it is in high
    > voltage high current, is it not easy to use some voltage comparators
    > for current sensing? Any detail information can be shared?


    Do *not* waste time on it: It has already been done and done well!

    The standard device is a "Motor Protection Relay", they are cheaper than you
    can buy the components for - and there is much more to the story than mere
    current for which a fuse would suffice; the current over time, the phase
    realationship and the heat capacity of the motor is factored in too.

    http://www.ab.com/industrialcontrols/products/supplemental_motor_protection/index.html

    and (yikes!):

    http://www.abb.com/global/abbzh/abb...e=us&m=9F2&c=BC8BA5A2FBD80967C1256DAA0044A679

    and:

    http://www2.automation.siemens.com/cd/is_schuetzen/html_76/ueberlastrelais.htm
    Frithiof Andreas Jensen, Apr 20, 2005
    #2
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  3. GoGo~

    GoGo~ Guest

    Thnak you for your reply.
    However, I want to build a external PCBA for it as I don't want to use
    such large size stuff!!!

    I want to use a voltage comparator to do something. But it is in low
    voltage components. How can I convert such 240Vac to 12Vdc voltage to
    drive the IC and triggering the IGBT for output controlling?

    I think transformer that are not suitable for my application. Use
    resistor series?





    "Frithiof Andreas Jensen" <frithiof.jensen@die_spammer_die.ericsson.com> wrote in message news:<d4538n$bfv$>...
    > "GoGo~" <> wrote in message
    > news:...
    >
    > > May I know how to design such kind of circuit? Because it is in high
    > > voltage high current, is it not easy to use some voltage comparators
    > > for current sensing? Any detail information can be shared?

    >
    > Do *not* waste time on it: It has already been done and done well!
    >
    > The standard device is a "Motor Protection Relay", they are cheaper than you
    > can buy the components for - and there is much more to the story than mere
    > current for which a fuse would suffice; the current over time, the phase
    > realationship and the heat capacity of the motor is factored in too.
    >
    > http://www.ab.com/industrialcontrols/products/supplemental_motor_protection/index.html
    >
    > and (yikes!):
    >
    > http://www.abb.com/global/abbzh/abb...e=us&m=9F2&c=BC8BA5A2FBD80967C1256DAA0044A679
    >
    > and:
    >
    > http://www2.automation.siemens.com/cd/is_schuetzen/html_76/ueberlastrelais.htm
    GoGo~, Apr 20, 2005
    #3
  4. GoGo~

    R Adsett Guest

    In article <>,
    says...
    > Thnak you for your reply.
    > However, I want to build a external PCBA for it as I don't want to use
    > such large size stuff!!!
    >
    > I want to use a voltage comparator to do something. But it is in low
    > voltage components. How can I convert such 240Vac to 12Vdc voltage to
    > drive the IC and triggering the IGBT for output controlling?
    >
    > I think transformer that are not suitable for my application. Use
    > resistor series?


    One of Allegros hall effect Current Sensors?

    http://www.allegromicro.com/hall/currentsensor.asp

    Robert
    R Adsett, Apr 20, 2005
    #4
  5. GoGo~

    Dave Guest

    GoGo~ wrote:
    > I have a 240Vdc DC motor with normal working current is 4A. For
    > the motor's rotor locking, its current will drive to 40A. So, I
    > suppose to design a external circuit for regarding motor. [...]


    Hell, isn't that called a 6A circuit breaker?
    Dave, Apr 20, 2005
    #5
  6. GoGo~

    Guest

    GoGo~ wrote:
    > Thnak you for your reply.
    > However, I want to build a external PCBA for it as I don't want to

    use
    > such large size stuff!!!


    then use a fuse... trying to rememebr the term for motor slow blow
    ones.


    > I want to use a voltage comparator to do something. But it is in low
    > voltage components. How can I convert such 240Vac to 12Vdc voltage to
    > drive the IC and triggering the IGBT for output controlling?
    >
    > I think transformer that are not suitable for my application. Use
    > resistor series?


    yup, dont need any of that with a fuse tho. Or if you want it
    resettable, a polywhatnot fuse. Or a cheap thermal mcb.


    NT
    , Apr 20, 2005
    #6
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