Page 1 of 4 123 ... LastLast
Results 1 to 10 of 36

Thread: When would the Auto reset on motor starter be used?

  1. #1
    Join Date
    Mar 2006
    Location
    close to greenville sc
    Posts
    1,013

    When would the Auto reset on motor starter be used?

    I opened the panel on a new machine with multiple motors this morning. I noticed that all of the motor starters were set on auto reset. Why would they do this?
    Military wives deserve the Purple Heart Medal. They are wounded every time their Soldier goes off to protect our freedom!

  2. #2
    Join Date
    Aug 2004
    Posts
    11,181
    Quote Originally Posted by hockeyoligist2 View Post
    I opened the panel on a new machine with multiple motors this morning. I noticed that all of the motor starters were set on auto reset. Why would they do this?
    Because they want the overloads to reset after a fault so the machine will start running again.

    I am not a huge fan of it in general, but there are some cases where having the tripped overload automatically reset makes some sense (like for a sump pump).
    Bob

  3. #3
    Join Date
    Jun 2009
    Location
    North Florida
    Posts
    119
    This will be done where access is not quickly available or you don't have he necessary personnel to quickly go to it. In a supervised situation, I don't recommend it since you can easily blow up a motor. But the overloads don't reset until an appropriate cooling time has passed so there is some protection. A good example is sumps of lift pumps where they are started by local controls and you don't have any supervision. You want them to run to failure so you don't flood the ground with crap (literally).

  4. #4
    Join Date
    Mar 2006
    Location
    close to greenville sc
    Posts
    1,013

    Cool

    I have never put one on auto, but I have been tempted. I have been out many dark and stormy nights resetting starters because of a power blip!
    Military wives deserve the Purple Heart Medal. They are wounded every time their Soldier goes off to protect our freedom!

  5. #5
    Join Date
    Jul 2006
    Location
    Hawthorne, California
    Posts
    1,369
    Quote Originally Posted by hockeyoligist2 View Post
    I have never put one on auto, but I have been tempted. I have been out many dark and stormy nights resetting starters because of a power blip!
    The auto reset only affects the overloads, and will do nothing if the starter drops out due to power sags.

    And you have to carefully consider the use of auto reset..in applications like conveyors or other machinery where an unexpected motor restart can cause injury or death if you change manual reset to auto reset you leave yourself open to severe liability.
    358.30, 230.70 and MWBC are officially hot button issues in my little world.

  6. #6
    Join Date
    Mar 2006
    Location
    close to greenville sc
    Posts
    1,013
    Quote Originally Posted by mxslick View Post
    The auto reset only affects the overloads, and will do nothing if the starter drops out due to power sags.
    Sorry, but I disagree. A motor cycling on and off due to power blips will cause the overloads to trip.
    Military wives deserve the Purple Heart Medal. They are wounded every time their Soldier goes off to protect our freedom!

  7. #7
    Join Date
    Aug 2004
    Posts
    11,181
    Quote Originally Posted by mxslick View Post
    The auto reset only affects the overloads, and will do nothing if the starter drops out due to power sags.

    And you have to carefully consider the use of auto reset..in applications like conveyors or other machinery where an unexpected motor restart can cause injury or death if you change manual reset to auto reset you leave yourself open to severe liability.
    Many conveyor applications I have worked on the things start and stop a lot on their own anyway.

    Since they are suppsoed to be guarded to prevent accidentally getting maimed by one anyway, how would an unexpected start of the conveyor add any additional risk??
    Bob

  8. #8

    design

    design dictates the use of the auto reset it should be a no volt restart circuit so that the sequence is restarted by human element or critical nature of application where the motor is expendable,usually for remote locations like rock crushers in a quarry , conveyer plant applications and vent fans in hazardous loctions ,if left unattended and motor keeps tripping on load fault, line fault protection will eventually trip the circuit and you will be looking to rewind or get a new motor

  9. #9
    Join Date
    Apr 2004
    Location
    Camarillo, CA
    Posts
    562
    Quote Originally Posted by hockeyoligist2 View Post
    I opened the panel on a new machine with multiple motors this morning. I noticed that all of the motor starters were set on auto reset. Why would they do this?
    Its a great way for the manufacturer to make follow-up sales of new replacement motors after the originals burn up from constant restarting without proper troubleshooting.

  10. #10
    Join Date
    Jul 2006
    Location
    Hawthorne, California
    Posts
    1,369
    Quote Originally Posted by hockeyoligist2 View Post
    Sorry, but I disagree. A motor cycling on and off due to power blips will cause the overloads to trip.
    Possibly, but having the overloads auto-reset will NOT automatically re-engage the contactor, unless the control input is a maintained contact. In that case of course the motor would restart when power is re-applied. Which is still a possible serious safety hazard, if someone was trying to figure out why the motor had stopped in the first place.

    Quote Originally Posted by petersonra View Post
    Many conveyor applications I have worked on the things start and stop a lot on their own anyway.

    Since they are suppsoed to be guarded to prevent accidentally getting maimed by one anyway, how would an unexpected start of the conveyor add any additional risk??
    Depends on the application. I make that statement based on a recommendation from a motor application guide, which mentioned a conveyor as one possible type of load that an unexpected restart would be dangerous.

    Even in an application where a conveyor started on its own, what do think would happen if someone was working on that conveyor because it wasn't starting at all, when the motor overload suddenly re-engages?

    There are literally millions of possible motor applications, and thus millions of reasons why/why not to use auto reset. Are we really gonna try to discuss them all in this thread? :grin:
    358.30, 230.70 and MWBC are officially hot button issues in my little world.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •