Why use an SSR when Lee states the Pro 4 20lb pot (100v) only draws 6.36 amps?

[benellinut]

I can always upgrade the relay on the board if I see repeated failures, no reason why this can't be doable as Ouch has already proved.

[MT Chambers]

I didn't read all the posts but why all that wiring for a cheapo Lee pot, is it to time the drips better?

[benellinut]

I didn't read all the posts but why all that wiring for a cheapo Lee pot, is it to time the drips better?

How's the weather up there on that pedestal?

[alfloyd]

If you will read the instructions manual, it will say that the "Main Output" for the relay model - normal open - AC 250V/3A - DC 30V/3A.

I would take this as saying that the PID is rated for a load not to exceed 3 amps.
You can run it at a 10 amp load, but it is not rated for that.

The output for the alarms is rated the same as the main output, 3 amps.

Yes, I do read the instructions.

Lafaun

[William Yanda]

'Cause bigger is better. Everybody knows that.

Duckin' and runnin'

[benellinut]

If you will read the instructions manual, it will say that the "Main Output" for the relay model - normal open - AC 250V/3A - DC 30V/3A.

I would take this as saying that the PID is rated for a load not to exceed 3 amps.
You can run it at a 10 amp load, but it is not rated for that.

The output for the alarms is rated the same as the main output, 3 amps.

Yes, I do read the instructions.

Lafaun

I don't know what you read but the relay in this PID is rated for 10 amp at 125VAC, all this info is in this thread, I'm sorry but you are wrong.

[benellinut]

'Cause bigger is better. Everybody knows that.

Duckin' and runnin'

That what "they" say.

[Handloader109]

If it works, it works. I run a 1500 watt 220 volt Magma pot. The first 2 20 amp SSR's burned out within a year and a half. I put in a 40 amp and it has been going for 3 years now. All 3 had a heat sink. I prefer to err on the side of caution myself, I have enough room on the bench for a larger PID box.

Well at 1500 watts @220v it only draws 6.8 amps..... You just had **** 20 amp ssrs. I think this only reinforces Benellinut's argument for leaving out the SSR. Extraneous, same as others putting in a fuse. But to each his own. I've an SSR as that is what I thought I needed when I jumped on the PID.

[Cmm_3940]

Well at 1500 watts @220v it only draws 6.8 amps..... You just had **** 20 amp ssrs. I think this only reinforces Benellinut's argument for leaving out the SSR. Extraneous, same as others putting in a fuse. But to each his own. I've an SSR as that is what I thought I needed when I jumped on the PID.

Keep in mind the internal relay comes from the same source as the SSRs -China. There are no guarantees that the QC of the internal relay is any better than the SSR.

The SSR is the more appropriate part for this application. Mechanical relays are not meant to be used in high cyclic rate applications for all the reasons previously mentioned. Will it work? Sure. Probably. For a while.

All these Chinese parts are only somewhat expected to work at their rated values at the time they leave the factory, with no guaranteed lifetime once deployed. I and others prefer to go overkill on the SSR because it is a cheap part, and it makes sense to do so to hopefully gain a reasonably long service life. A cheap "40" amp Chinese part is likely to last longer than a cheap "20" amp part at a steady ~6A draw. If you expect 100% duty cycle at the rated value from one of these things, you're dreaming. It's worth the $8-$10 to me to not have to be tearing my PID apart to replace cooked parts.

Also, don't forget about the inrush current, which will be higher than the steady-state current draw, so it's best to leave yourself some headroom in any case. This will have more of an impact with the constant rapid on/off cycle of the PID than it will with the factory thermostat.

[benellinut]

Keep in mind the internal relay comes from the same source as the SSRs -China. There are no guarantees that the QC of the internal relay is any better than the SSR.

The SSR is the more appropriate part for this application. Mechanical relays are not meant to be used in high cyclic rate applications for all the reasons previously mentioned. Will it work? Sure. Probably. For a while.

All these Chinese parts are only somewhat expected to work at their rated values at the time they leave the factory, with no guaranteed lifetime once deployed. I and others prefer to go overkill on the SSR because it is a cheap part, and it makes sense to do so to hopefully gain a reasonably long service life. A cheap "40" amp Chinese part is likely to last longer than a cheap "20" amp part at a steady ~6A draw. If you expect 100% duty cycle at the rated value from one of these things, you're dreaming. It's worth the $8-$10 to me to not have to be tearing my PID apart to replace cooked parts.

Also, don't forget about the inrush current, which will be higher than the steady-state current draw, so it's best to leave yourself some headroom in any case. This will have more of an impact with the constant rapid on/off cycle of the PID than it will with the factory thermostat.

Finally, someone with reasonable and valid points. Your right on the money with everything you said and we each have to decide which way we want to go. I'm just offering up an alternative, one that gives you a much smaller and simpler unit, there is a trade off for everything. For me, I'll take the chance I may have to solder a new relay on the board, it takes me less then one minute to take the unit apart to this condition (pic below) and a few minutes to get my tools out and solder a new relay on the board. Probably no longer then it would take to replace a failed thermocouple and no more time to replace a failed SSR.

BTW Note the amp rating printed right on the relay.

[leadman]

You may get this to work ok depending also on the ambient air temperature that the unit is in. I use mine here in Phoenix and they get plenty hot in the summer. The unit can get over 120 degrees without being switched on.
The internals of the relays have contact points just like the ignition system on old gas engines. There was a reason the tune up schedule was 10,000 miles on most of these.

I do have a Bosch 30a fused relay and have thought of installing this if I have an SSR go out just to see what happens. The PID to run a relay versus a SSR is different and not interchangeable though. Found this out the hard way when a vendor on EBay sold me some mismarked PID units.

I have added heat sinks and on one unit an electric fan like a computer uses and performance is much better. The unit on my pot has run for more than 8 hours many times without being shut off.

[alfloyd]

Yes, the relay is rated for 10 amps but, the PID is only rated for 3 amps.
Look at the spec sheet.

Lafaun

[JonB_in_Glencoe]

Yes, the relay is rated for 10 amps but, the PID is only rated for 3 amps.
Look at the spec sheet.

Lafaun

I wonder if they downgrade the rating to 3 amps, due to the delicate connections between the PCB and the terminals in the chassis ?

It might be prudent to add some 'hard wiring' between the Relay contacts and the terminals.

[benellinut]

Yes, the relay is rated for 10 amps but, the PID is only rated for 3 amps.
Look at the spec sheet.

Lafaun

OK, I'll agree that's what's printed on the MYPIN spec sheet --> http://www.mypinchina.com/uploadfile...1494651265.pdf
but as you can clearly see the relay is rated for 10 amps at 125 volts. The relay is what's sending volatage to the pot, the PID is just switching the relay on and off.

A couple other things, that 3 amp rating your talking about is at 250 volts ac, not 125 volts ac, again look at the ratings on the pic of the relay I posted above and you'll see printed on the relay (and also on the relay spec sheet linked prior)
10 amps at 125 v ac
5 amps at 250 v ac
5 amps at 30 v dc
Amperage ratings change depending on the voltage and if it's being used to control AC or DC.

I have already run the pot for a couple hours, if the PID connectors or the board connections from the relay to the connections couldn't handle the 6.36 amps of the pot it would have gotten hot or smoked and it did neither as I kept a very close eye on it.

Take a look at the comparable PID made by Auberins and you'll see the output is rated for 10 amps at 125 volt ac
http://auberins.com/index.php?main_p...&products_id=1 There isn't any reason why a PID with an internal relay can't be used to run this Lee Pro 4 20lb pot that draws a max of 6.36 amps, this is doable.

Lastly, I'll once again point out, I'm not the first one to do this. Ouch has been using his for three years and sometimes to run another pot that draws even more amperage. Read his post on the first page of this thread, #13 linked below.
http://castboolits.gunloads.com/show...=1#post3250816

[JonB_in_Glencoe]

Yep, your PID should be good to go.

I do, however, find your thread title a bit curious. In it, you ask a question...
Then, when myself and others offer our reasons why, you get defensive ?
(and while I was skeptical, I remained tactful and open minded..and gee, we were just trying to help)

Then in your last post, you state the following...

There isn't any reason why a PID with an internal relay can't be used to run this Lee Pro 4 20lb pot that draws a max of 6.36 amps, this is doable.

hmmm, maybe your title question was rhetorical ? IDK ?
ANYWAY, Good luck and I will avoid your questions in the future.

[benellinut]

Yep, your PID should be good to go.

I do, however, find your thread title a bit curious. In it, you ask a question...
Then, when myself and others offer our reasons why, you get defensive ?
(and while I was skeptical, I remained tactful and open minded..and gee, we were just trying to help)

Then in your last post, you state the following...

hmmm, maybe your title question was rhetorical ? IDK ?
ANYWAY, Good luck and I will avoid your questions in the future.

I think the title was appropriate, potato, patata. Remember this thread is now two months old, I've done a lot of research since so when I now say it's doable that opinion is a conclusion that evolved over that time and backed up by someone who had already proven it.

BTW, It wasn't the reason's offered, (none that I saw as valid nor swayed me) that made me defensive, it was the offensive nature of some of the posts.

[Mal Paso]

Also, don't forget about the inrush current, which will be higher than the steady-state current draw, so it's best to leave yourself some headroom in any case. This will have more of an impact with the constant rapid on/off cycle of the PID than it will with the factory thermostat.

No inrush current with a resistive load like a heater. I agree with the rest though. That relay will be chattering like a telegraph close to operating temperature.

[benellinut]

No inrush current with a resistive load like a heater. I agree with the rest though. That relay will be chattering like a telegraph close to operating temperature.

Not as much as you think, I'll back off the dwell time a little to reduce that chatter. Letting it overshoot and undershoot a little isn't going to hurt.

[benellinut]

From here on in I'll let you guys chat it up, be it good or bad, if you want to knock it or me feel free, I don't care. There really isn't anything more I have to add, pretty much any info relevant to my build has been posted and my points posted. I'm done defending my reasons, disproving & correcting bad information and myths.

For the folks looking to build a PID, all I can say is don't take everything you read on any forums as fact, including my opinions. Do your own homework, understand the trade off's and do what makes you happy.

[OuchHot!]

benellinut, you are starting to see why I don't bother with this site much. In three plus years, I am sure I have better than 20hrs on a pro-melt and at least that on the lee. The unit I use appears identical to yours. I have some more demanding applications for PID where I did use an ssr and found the run of the mill ssr to be very sensitive to temperature and needful of careful heatsinking. My spare bedroom is an electronics lab, I make my own choices and learn from my own mistakes. I put two of these PID in a box, the other runs the hotplate for my mold warming. I have no problems with that use either. Given the entire electronics suite in your automobiles is straight from China, I suggest everyone stay home or at least not drive any further than you want to walk.