User Tag List

Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 25

Thread: Digital Circuit Breakers

  1. #1
    Join Date
    May 2019
    Location
    Chicago, IL
    Posts
    69
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    Digital Circuit Breakers

    These breakers have recently gotten UL approval.
    But it will probably be awhile before we see them in Home Depot :

    https://www.google.com/amp/s/spectru...akers.amp.html

  2. #2
    Join Date
    Apr 2008
    Location
    Ann Arbor, Michigan
    Posts
    7,807
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    190522-0446 EDT

    See https://pdfs.semanticscholar.org/d79...6f773b6803.pdf

    Look at SiC voltage drop compared to an electromechanical switch. Possibly at least 100 times more power loss in the SiC switch compared to a silver contact switch for the same switched current.

    In the early 1960s I was involved in the early demonstration of an electronic breaker. I used SCRs, these have high voltage drop when on, about volt or so, but lower than SiC devices. Silver contacts are in the millivolt range.

    For a lot of purposes I don't think a solid-state power switch is better than electromechanical. But electronic control of the switch has some great advantages.

    .

  3. #3
    Join Date
    Jun 2017
    Location
    Memphis, TN
    Posts
    2
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)

    They aren't the only one

    Quote Originally Posted by synchro View Post
    These breakers have recently gotten UL approval.
    But it will probably be awhile before we see them in Home Depot :

    https://www.google.com/amp/s/spectru...akers.amp.html

    ABB unveiled this 1p 1500VDC breaker for solar and energy storage applications a few months ago. Seems like they may work for certain niche markets.

    https://new.abb.com/news/detail/1849...en-power-grids

  4. #4
    Join Date
    May 2019
    Location
    Chicago, IL
    Posts
    69
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Agree that solid state switches can't match the low losses of mechanical contacts. I see it's becoming common to see SCRs combined with mechanical contactors inside an ATS to leverage the best advantages that each one has.
    SiC can provide faster switching than SCRs and it has no restriction on when it can turn off (vs. SCRs that stay on till the next zero crossing). So I'm sure there will be new applications where SiC will excel.

  5. #5
    Join Date
    Jan 2011
    Location
    United States
    Posts
    9,171
    Mentioned
    1 Post(s)
    Tagged
    1 Thread(s)
    I'll pass.


    But as I've said before, this was and is inevitable.

  6. #6
    Join Date
    Feb 2003
    Location
    New York, 40.7514,-73.9925
    Posts
    4,820
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by synchro View Post
    Agree that solid state switches can't match the low losses of mechanical contacts. I see it's becoming common to see SCRs combined with mechanical contactors inside an ATS to leverage the best advantages that each one has.
    We see this combination for UPS static bypass switches, but for static transfer switches, it is mostly just the solid state portion.
    Ron

  7. #7
    Join Date
    Apr 2008
    Location
    Ann Arbor, Michigan
    Posts
    7,807
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    190522-1601 EST

    synchro:

    You can not shunt a solid-state switch with a mechanical contact in a circuit breaker to reduce steady state power loss, and still expect to obtain a faster trip time than the trip time of the mechanical contact.

    .

  8. #8
    Join Date
    Feb 2003
    Location
    New York, 40.7514,-73.9925
    Posts
    4,820
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by gar View Post
    190522-1601 EST

    synchro:

    You can not shunt a solid-state switch with a mechanical contact in a circuit breaker to reduce steady state power loss, and still expect to obtain a faster trip time than the trip time of the mechanical contact.
    For some UPS static bypass switches, they use the solid state switch to make the fast transfer, then close the parallel mechanical bypass contactor, then open the solid state switch. The transfer back to UPS double conversion is deliberate, so it will close the solid state switch first and reverse the process.
    Ron

  9. #9
    Join Date
    Apr 2008
    Location
    Ann Arbor, Michigan
    Posts
    7,807
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    190522-1554 EDT

    ron:

    Parallel contacts are fine for a turn on application, but that is not a circuit breaker application.

    Now consider a turn off application. Virtually any loading on a switch has some inductive component. What happens to the voltage across a switch when you open a circuit to a load while current is flowing? So what is the result of instantaneous tripping?

    .

  10. #10
    Join Date
    Aug 2017
    Location
    Los Angeles CA
    Posts
    216
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Also semiconductors can fail in a short condition. How many times have you replaced a light dimmer that won't dim, just full brightness all the time! That's because the Triac or SCRs have failed shorted.

    At a minimum these solid state breakers are still going to have an internal series fuse or I would guess they never get approvals.

Posting Permissions

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