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Re: [TCML] SIDAC ratings. was: SISG success
Finn Hammer wrote:
Let me show you how I rephrase the descriptions below, to make them
usefull for my ponderings.
Vdrm1 voltage 275V
"Peak Off-state Voltage
Maximum voltage that can be applied while maintaining off state."
This one says: If you apply more than 275 volts, the device turns on.
More like, the device is guaranteed to stay off if you stay below 275.
Go above 275, and it might fire.
Then there is:
Vs@Vdrm1 voltage 350V
Maximum voltage prior to switching to on state."
This one says: The device doesn`t turn on unless you apply more than 350
volts across it..
if you apply more than 350, the device is guaranteed to turn on. At less
than 350, it might not (unless you're less than 275, in which case it's
guaranteed to NOT fire).
Combine them, and you have: The device turns on at 276 volts, but not
before 351 volts.
This is of course a bunch of rubbish to say, so probably my command of
the english language is lacking sophistication.
No.. it's just sort of clunky way of saying the behavior is not
guaranteed between 275 and 350 volts.. it might fire, it might not.
We have seen that the SIDAC`s maintain remarkably accurate turn on
voltages, so any claim that it is situated "somewhere in between" 275V
and 350V is preposterous.
But which of these ratings describe the breakdown voltage of the device?
Not an unreasonable question to ask of a device that acts as a crowbar
to protect another much more expensive device.
Guaranteed to break down somewhere between 275 and 350, so if your
device can be damaged by 300V but not 250, then you're using the wrong
I suspect that any one device will have fairly consistent properties.
Sort of like a spark gap.. hard to predict the exact breakdown voltage,
but once you know it, it's pretty consistent.
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