Page 1 of 1

circuit protection

Posted: Fri Feb 24, 2017 7:58 am
by jward
What do you do to protect various components on your control system? Where are the smart places to add protection?

I have read stuff about using fuses here or there, using a relay vs SSR vs contactor depending on what one is controlling, builtin GFI, opto-isolators or diodes, ground this but not that or only one end, and etc.

Re: circuit protection

Posted: Thu May 25, 2017 9:18 pm
by oakbarn
I put in "kill" switches for all power. I have several dedicated circuits but have also installed regular light switched or the Aubrins Push Button LED Switches on all my elements and pumps. I have found that when an SSR fails, it has failed in the powered on state. Without the positive "kill", my pumps would have been running dry. I place the switches after the SSR and the device.

Re: circuit protection

Posted: Fri May 26, 2017 6:46 am
by clearwaterbrewer
Good practice to fuse before reducing wire size below the existing protection.

If you have a 50A breaker in the building panel, and bring it via #8 wire to your brew panel, and want to separate out to 3 22.9A elements, and a 15A feed for 120V for bumps and such... run the #8 wire to a 50 A contactor, then continue 8 GA wire to each of 3 30A breakers and the 15A breaker, then on the *protected* side of the breaker, you can reduce to 10GA wire for the 30A and 14ga for the 15a circuit...

I do break this general rule on occasion when running indicator lights, I will run 18ga the short distance from the Element outlet to the DIN rail where I have a 1A fuse, and then to the indicator lamp in the door...

It is all pretty logical protect small wires from getting big current on the high voltage side......

Re: circuit protection

Posted: Sun May 28, 2017 7:05 am
by oakbarn
I also use the 80% rule. For anything rated at 15 Amps (!4 AWG Wire, Switch, Outlet,Circuit Breaker), I limit the max amperage of widgets to 12 amps or 1320 Watts. I also have every circuit GFI protected.

Re: circuit protection

Posted: Mon Sep 21, 2020 3:54 pm
by jward
I started to convert my rig to electric heating. Here is the start. I will get power from a 30 amp dryer outlet that powers a spa panel with a 50 amp GFCI breaker in it. The BCS will control power with the SSRs.
element start.jpg
element start.jpg (117.63 KiB) Viewed 232 times