On 19/07/2020 17:45, Cursitor Doom wrote:
On Sun, 19 Jul 2020 17:13:00 +0100, PeterC
wrote:

On Sun, 19 Jul 2020 15:31:19 +0100, Mike McLeod wrote:

I only ask because I'm making up a controller for one. I don't find
the 3 heat settings provide enough choice so I'll be controlling a
small triac via a PWM chip. Although the max current draw of this
appliance is only 350mA, the triac (a Z0607) is pretty puny and I
don't want it operating at too close to its max ratings obviously. I'm
using a snubber to be on the safe side WRT to back EMF anyway.

Here's the datasheet for the triac:

https://www.st.com/resource/en/datasheet/z00607.pdf

Will that do it or is something more meaty required?

Mine's 16/31/60W nd the PF is 1; VA and W show no difference.
Given the possible ****it! level (fire - bedding - unattended) having a good
margin is well worth it.

It would appear to be already sufficiently de-rated, though. That
triac is good for 800mA (and 600V!) and he's only putting a maximum of
350mA through it. Given the load is near enough purely resistive as
you say, there should be no problem. Where's the fire going to come
from??


Is the 350mA an average over the temperature range of the blanket. Could
the current be higher than 350mA at some point during the heating cycle?

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