Master Pot adding PID

[gtgeorge]

I have a couple PID controllers I was using on Lee Pots by just turning the controller on the pots up all the way and plugging the power cord into the PID with great results. I then got a Pro Melt and did the same thing and all was good. I now have a Master Pot and there is no joy when I plug it into the Pid as I did with the others. Will I have to wire straight in to the heating element on the Master Pot? I am puzzled as to why it would not work so off to look at a wiring diagram but thought I would ask here for those that are all knowing in these matters :)

[jmorris]

If you have been relying on the relay in the PID itself, you might be overloading it. If you haven't already "let the smoke out of it" you might try using a relay good for the current that the element draws and have the "little" relay in the PID control trigger it.


The same way the contacts in your cars ignition switch cannot pass enough current to run the starter motor for the engine, there is a separate solenoid in between that takes the signal from the "weak" switch (good for a few amps) and sends the starter several hundred amps.

[gtgeorge]

Thanks JM, I let the smoke out (all contained in the glass 8amp fuse) and will increase the internal wire size to match the load and the fuse for that side of the circuit to match as well then. All the components are indeed big enough for the 13 amp load but was wired for 8 with protection :smile: Thankfully I am blessed with my Father still being available with his thorough knowledge of electronics as I seem to have been lost when that knowledge was passed out.

[jmorris]

You have to love fuses. You might just use an extra relay anyway just to add another "fuse". One you install on the output side will likely be a lot easier to change down the road than one soldered to the board inside the PID.

[gtgeorge]

I use a separate relay on the inside already. Dad didn't play when he over engineers things.

It has an on off switch for the main power as well as for the circuit coming off the relay. It has a fuse for each side and the alarm as well. And the probes are plug in instead of hardwired to be changed out at will. He needed something to keep him busy so I had him design and build 3 of them with the knowledge of what I may use them for as equipment changes along the way.

[jmorris]

You should have it covered.

[gtgeorge]

Thanks for your help as for some reason I didn't think about the extra load of the pot being in excess of the original fuse and power circuit of the power circuit. Glad for those little glass smoke catchers too!

[DaveInFloweryBranchGA]

Yes, a fuse can be a very good thing, especially if you're using a setup for an application it wasn't originally designed for and get caught by a change in specifications like current demand increase. [smilie=b:

[gtgeorge]

Finally got the box checked that all wiring was appropriate for a 15 amp circuit and installed a 15amp fuse that had me casting for hours within 2° . Checked temps at different points on the box and all areas stay under 120° F. I may install a small cooling fan at some point but happy all the smoke was contained in the little glass tube for easy removal of said smoke. :)