Page 2 of 2 FirstFirst 12
Results 14 to 23 of 23

Thread: Contactors

  1. #14
    Join Date
    Sep 2002
    Location
    Virginia
    Posts
    4,750
    Post Likes
    Beacon is crap , and their are others out of china , none are allowed in my truck

    And yes , Im guilty of never checking my own stuff , and it seems to last a long ass time

    The 45-5 crapped out 2 weeks ago on my 10 year old Rheem , and its sporting a Titan HD now

    Contactor looks fine still

  2. #15
    Join Date
    Dec 2012
    Location
    columbus, OH
    Posts
    5,500
    Post Likes
    I will add that the soot and pitting on a contactor could be related to issues beyond the contactor itself.

    1. Short cycling
    2. Low voltage, either line or control
    3. High load on startup, (related to 1, short cycling)
    4. Ants are in the sugar


    Sent from my iPhone using Tapatalk

  3. #16
    Join Date
    May 2018
    Location
    Central Florida
    Posts
    183
    Post Likes
    The problem you’re describing has to do mostly with the corrosive effect of arcing when the points are closing or opening.

    The ark is caused by the potential between one side and the other.

    I cant remember exactly where I saw this (online or in a mfg sponsored course) but you can look up “ark suppression” online to get deeper.

    Basically an arc occurs when you have a high level of potential between your points, which can result in extremely brief temperatures of thousands of degrees. The result of this is pitting and blackening of the points.

    This is why you will see some mfg’s that have one side of a single phase split as a dedicated hot.... so that when the points close there is neutral potential between both sides. The most real world approach to this is why you see single pole contactors (with the other side simply being a pass through).

    Have you ever run across a burned single pole contactor?

    Some high end systems will monitor the frequency of incoming high voltage and only allow the contacts to close when the high voltage sine waves are neutral.

    The end result in both situations however is that you close your points with little to no elecical potential.

    To confront arcing and pitting in residential (single phase split) I would recommend installing a 1 pole contractor... and of course wiring it correctly.

  4. #17
    Join Date
    Jan 2004
    Location
    PA
    Posts
    75,689
    Post Likes
    Quote Originally Posted by 3.14 View Post
    The problem you’re describing has to do mostly with the corrosive effect of arcing when the points are closing or opening.

    The ark is caused by the potential between one side and the other.

    I cant remember exactly where I saw this (online or in a mfg sponsored course) but you can look up “ark suppression” online to get deeper.

    Basically an arc occurs when you have a high level of potential between your points, which can result in extremely brief temperatures of thousands of degrees. The result of this is pitting and blackening of the points.

    This is why you will see some mfg’s that have one side of a single phase split as a dedicated hot.... so that when the points close there is neutral potential between both sides. The most real world approach to this is why you see single pole contactors (with the other side simply being a pass through).

    Have you ever run across a burned single pole contactor?

    Some high end systems will monitor the frequency of incoming high voltage and only allow the contacts to close when the high voltage sine waves are neutral.

    The end result in both situations however is that you close your points with little to no elecical potential.

    To confront arcing and pitting in residential (single phase split) I would recommend installing a 1 pole contractor... and of course wiring it correctly.
    Lots of single pole contactors burn the contacts. Welding together is not uncommon on single pole contactors.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  5. #18
    Join Date
    May 2018
    Location
    Central Florida
    Posts
    183
    Post Likes
    I’m not familiar with seeing them burnt but maybe it’s because they are somewhat rare.

    I wonder if the phase shift of the capacitor could throw neutral potential off?

  6. #19
    Join Date
    Sep 2012
    Location
    FL
    Posts
    38
    Post Likes
    [QUOTE=3.14;25565662]The problem you’re describing has to do mostly with the corrosive effect of arcing when the points are closing or opening.

    The ark is caused by the potential between one side and the other.

    ----------------

    Reason for arc.. You cannot change the voltage instantaneously in a cap ( I (cap) = C dv/dt cannot divide by zero), You cannot change the current instantaneously in an inductor ( I (inductor, motor winding) = L di/dt ) Try you fry things burn things up. Snubber circuits help. Think points in a car always needing attention. Electronic ignition better. Emerson sure switch contactor upgrade really only solution or the like if you don't have high quality parts. Relays are under designed to fail to make money. Look at (expensive) oven timer circuit boards, cheap relays fail. Those tricky Chinese.

  7. #20
    Join Date
    Jan 2004
    Location
    PA
    Posts
    75,689
    Post Likes
    Quote Originally Posted by 3.14 View Post
    I’m not familiar with seeing them burnt but maybe it’s because they are somewhat rare.

    I wonder if the phase shift of the capacitor could throw neutral potential off?
    I think its because it doesn't make a difference if its a 2 pole or single pole contactor. Your still drawing LRA when the contactor closes. And the contact is still under load when it opens. There will be an arc each time.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #21
    Join Date
    Apr 2012
    Location
    virginia
    Posts
    21
    Post Likes
    We use to offer solid state contactors as an upgrade. They monitor the phase and only close or open on 0 v , and offer over/under protesction, and random start delay(imagine 25 units at an apartment building starting at the same time after power failures). This completely eliminates arcing, the most feared enemy of contacts, second to ants.

  9. #22
    Join Date
    Jun 2012
    Location
    Northern NV
    Posts
    1,212
    Post Likes
    I need 3 phase contactors from somewhere other than China!

    All of the american made (old) contactors seemed to last 20 years. The chink stuff? Season or two..

  10. #23
    Join Date
    Nov 2014
    Location
    Northern Idaho
    Posts
    596
    Post Likes

    Contactors

    If you want to get a higher quality contactor, look into IEC rated contactors, rather than definite purpose.

    NEMA > IEC > Definite Purpose

    NEMA is not practical at all for residential
    Last edited by GoCougs; Yesterday at 09:40 PM.

Page 2 of 2 FirstFirst 12

Posting Permissions

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

Related Forums

Plumbing Talks | Contractor MagazineThe place where Electrical professionals meet.