PID SSR vs mechanical relay

[jaroporter]

just want to shoot this out to people as i don't usually see the distinction made in threads talking about PIDs (maybe because in all practicality it doesn't matter much?).

admittedly i've not used a PID before, but to me it seems like a SSR output makes more sense for this application. but i'd appreciate it if anyone had any thoughts either way in case there's something important i'm not aware of
been looking at the inkbird units, mainly because the auber would be US import i think - if anyone has any recent comments on this brand's functionality/reliability it'd be interesting.

for me it'll be only the usual controlling pumps and elements, though i'll leave it as an general question about PIDs as i'd be interested to know more anyways..

cheers

[aamcle]

Go with a PT100 on the PID as thermocouples (k type + others) are very hard to calibrate, there is no need to import anything I have two PID's one I bought cheap from the Bay it's been reliable for the past three years. The other I bought from http://www.omega.co.uk it's fancy and reliable but I have not used it host of functions.

Mechanical relays are supposed to suffer if they pop open and closed to rapidly as they would when your using you PID as a pulse width modulator to control the boil.

ATB. aamcle

[themadhippy]

In general mechanical relays aren't very good at switching heavy loads off and on at a rapid rate and standard ssr's dont like heavily inductive loads like motors or transformers,so for a heater being controlled by a pid an ssr is a better choice of the two,but a pump thats just being switched on and off a relay is better.

[jaroporter]

many thanks for the replies. was figuring that the SSR would be more suited if the PID is switching rapidly, but that's an interesting point about inductive loads. is the main concern overcurrent (or overvoltage) causing failure of the SSR, or something else?

[Hogarth]

I once hooked up a mechanical relay to a PID and it wouldn't switch at all.

[Fil]

rapid switching of an SSR will create heat, a ebay standard FORTEK 25A SSR when switching 2 x 1.5kw elements generated temps over 60C when measured 2nd vane down on the heatsink mechanically attached to the SSR base.

A SSR rated @ 40A or 60A may run cooler?? but if planning on boxing up perhaps consider an external heatsink or fan to help vent the box of heat.