Announcement

Collapse
No announcement yet.

Phase angle switch for limiting inrush current?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Phase angle switch for limiting inrush current?

    I apologize in advance if this ends up being total bullsh*t

    I've been thinking about something. A normal transformer operating in best case scenario when powered on experiences magnetizing current plus the momentary short circuit load while the capacitors charge up, correct?
    However, from what I've been reading, inrush can be compounded severely depending on whether or not it switches at the zero crossing point or if the incoming phase angle of the AC waveform opposes the angle of the remanent flux in the core. I've been thinking about a way to avoid switching on to these conditions.
    What if we took a high hysteresis device, lets say, a glorified core memory which would be disconnected from the mains to give us our reference to the magnetized state of the transformer core. During power on, when the AC wave opposes the magnetized state of the "core memory" we can use the induced voltage in an inverting amplified circuit to trigger a relay during the optimal time.
    Its just an simplified idea, but would this work?
    If I have a 50% chance of guessing the right answer, I guess wrong 80% of the time.

  • #2
    Aha! Another solution looking for a problem.

    it should not be a challenge to engineer up a zero-crossing detector to control incoming mains current. But considering the millions of electronic products without such protection circuits have worked reliably (for what, close to 100 years now?) for ages, what are we trying to achieve? Would it work? MAybe, but please define "working".

    Unless it is seriously under-designed, inrush doesn;t hurt the transformer, those wires won;t overheat in half a second of that. In higher power circuits, inrush limiters save power switch contacts. One solution to that is to use the switch to control a power triac, the triac then controls the mains. Presumably the rectifiers on the secondary side have built in tolerance. The 1A 1N4007 has a 30A surge rating for example.
    Education is what you're left with after you have forgotten what you have learned.

    Comment


    • #3
      Originally posted by Enzo View Post
      In higher power circuits, inrush limiters save power switch contacts. One solution to that is to use the switch to control a power triac, the triac then controls the mains.
      I wuz gonna say, hasn't Peavey done this for the last what, 35 years. Oh YEAH! Great Idea! What's old is new again, again.
      This isn't the future I signed up for.

      Comment


      • #4
        Originally posted by Leo_Gnardo View Post
        I wuz gonna say, hasn't Peavey done this for the last what, 35 years. Oh YEAH! Great Idea! What's old is new again, again.
        Leo, I've been developing quite a refined skill of coming up with brand new circuit ideas which have been around for 35 years. I think I'm really coming into my own with it. Coming up next!: I invent servo biasing. Its gonna be great!
        If I have a 50% chance of guessing the right answer, I guess wrong 80% of the time.

        Comment


        • #5
          Originally posted by SoulFetish View Post
          Leo, I've been developing quite a refined skill of coming up with brand new circuit ideas which have been around for 35 years. I think I'm really coming into my own with it. Coming up next!: I invent servo biasing. Its gonna be great!
          Don't worry I've done similar. When I show my ideas to the real experts (my ham radio friends, they really know their stuff!) find out once again, come up with an idea so old it's been obsolete for decades.
          This isn't the future I signed up for.

          Comment

          Working...
          X