circuit protection

Discussion of the physical aspects
Post Reply
jward
Posts: 68
Joined: Sun Oct 04, 2009 9:38 pm
Bot?: No

circuit protection

Post 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.
User avatar
oakbarn
Posts: 846
Joined: Thu Jan 05, 2012 2:28 pm
Bot?: No
Location: Texas
Contact:

Re: circuit protection

Post 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.
clearwaterbrewer
Posts: 383
Joined: Wed Feb 09, 2011 3:43 pm
Bot?: No
Location: Clearwater, FL
Contact:

Re: circuit protection

Post 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......
User avatar
oakbarn
Posts: 846
Joined: Thu Jan 05, 2012 2:28 pm
Bot?: No
Location: Texas
Contact:

Re: circuit protection

Post 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.
jward
Posts: 68
Joined: Sun Oct 04, 2009 9:38 pm
Bot?: No

Re: circuit protection

Post 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 172 times
Post Reply