SSR control

That SSR

(snip)

There are two basic kinds of control available.

There is on off control (similar to your furnace thermostat) that provides full power till some temperature is reached, and then turns off till some slightly lower temperature is reached. The power cycles on and off as the temperature bounces up and down between two limits. The placement of the temperature sensor has a big effect on the performance, so some experimentation mat be necessary, and you will probably want a sensor with a temperature adjustment on it. The temperature control on any electric water heater is this type, and they have heavy contacts to deal with the heater current, directly. But you could use one of them to operate your SSR and it would last even longer.

The second, more expensive but more versatile common mechanism is the PIC controller. For this application you would want one with a relay contact output, to drive your SSR, since it needs line voltage to operate. The controller would have settings for the time cycle it operates the SSR with, and as the temperature approaches the setpoint, the on time gets to be less and less of the cycle time, till the temperature just flattens out at the desired temperature. For this to work, you will have to tune the PID values, for stability and lack of overshoot. These controllers are available over a wide range of prices, and come up in great numbers on Ebay auctions. Thew trick is getting one with the features you need (temperature sensor type and output signal) from Ebayers who may not know what they are selling.

For example:

-280 volts AC yours requires. So the search continues.

But even if you get a PID controller, you should have an on off thermostat in series with the SSR, to prevent thermal runaway, in the event of SSR or controller failure. SSR's usually fail on. And you also need a relief valve to prevent sensing steam back into the supply line if that fails.

Hope this is the right place to ask. I need some type of manual variable control for a P&B SSR (240a25). It will be used to control a 240V, 4500 watt water heater element in a electric kettle.

A good dimmer switch or if it even works would that wear out the SSR quick. I only need a duty cycle over one or two seconds with some type of proportional control. TIA

Sorry, I'm not an engineer, try to dumb down to me. Is there a more appropriate NG for this question? Or just flame away.......

Thanks. I'm a home brewer trying to regulate a 240V water heater element rated at 4500 watts that I use in a brew pot. Evidentally, an infinite switch is out of the question. I have a P&B SSR-240a25 relay ordered. What I am trying to do is manually control my temperatures when boiling. I need some type of input that I can vary if the boil gets too out of control. A few home brewers use thermistors and a PID. Obviously that is a little beyond me and overkill for what I want. Any suggestions are appreciated.

"John Popelish" ........>

Previously posted so you don't have to go back. and thanks.

Thanks. I'm a home brewer trying to regulate a 240V water heater element rated at 4500 watts that I use in a brew pot. Evidentally, an infinite switch is out of the question. I have a P&B SSR-240a25 relay ordered. What I am trying to do is manually control my temperatures when boiling. I need some type of input that I can vary if the boil gets too out of control. A few home brewers use thermistors and a PID. Obviously that is a little beyond me and overkill for what I want. Any suggestions are appreciated.

"John Popelish" ..........

I guess I'm looking for a simpler solution if there is one. On my fellow HB guys just cut off the lights from a Christmas chaser light set to provide

The SSR will not wear out. A dimmer switch will not work well because they are cycle-by-cycle phase control and most AC SSRs are zero crossing actuated. You need a duty cycle modulator of a 1/2 Hz ( for 2 secs) drive signal for the SSR. This is a simple TTL oscillator with constant period and manually adjustable ON time that spans something like 1% to

background - not much yeah, shortwave kit that worked & other little pud projects yeah yeah - I save all those.

Honestly, I probably won't build it unless I have to. Just looking for an easy fix, but I will if I need to. Thanks for your time.

Your SSR-240A25 is an SSR replacement for an AC relay drive, intended for existing system replacements. You should cancel that order and ask for SSR-240D25.

Cancel that order and ask for an SSR-240D25.

Thanks people for you quick and informative replies. This must be a great group. If you ever have any dental questions pop over to sci.med.dentistry. There's a good core group there that will be as good to you - as you have been to me. I'm on a little sabbatical from there because of dumb questions such as mine but asked with a chip on the shoulder (pun).

carabelli

"carabelli"

From foreign lingo gibberish into English gibberish.

......... Phil

"carabelli"

Leave out the technical talk.

Give the part number of the P&B SSR you plan to use.

........ Phil

"carabelli"

That SSR is a "zero turn on" type and is on/off controlled by a AC input voltage of 90 to 280 Vrms.

A device that can make a small 240 volt lamp flash on and off is all you need, provided it can be adjusted to give fully on.

The SSR input can be connected across the lamp.

....... Phil