BIAB kettle controller build

[bruce_the_loon]

Christmas break turned into a controller panel construction time. Based on a single phase 240V AC design modification to one of doug293cz's circuits with some automation additions. Will try and get the circuit diagram moved from paper to electronic. This will be driving up to a 3500W element which will pull 14.6A at 240V.

The automation additions, relay on the pump specifically, is designed so that I can hook it up to a RPi or similar later on. Debating on whether to get an EZBoil imported or just build something using the RPi and something like CraftBeerPi.

First photo is the front panel including switches, indicator lights, sockets and amperage meter. Isolator is 3 pole 40A rated and the kettle element socket is a 16A IEC 60309 2P+E industrial socket with solid pins. Pump socket is a 16A IEC C13 panel mounted socket. Panel is fed by a dedicated 20A circuit with IEC 60309 socket and plug with 4mm² cabtyre cable.

Inside view of the front panel with all the temporary control wiring in place for testing. Waiting for delivery of some plug-in connectors to build the front panel control harness. Primary AC is rigged using 4mm² (12 AWG) flexible wiring for the isolator and socket and 2.5mm² (14 AWG) for the ground line. Pump plug will be wired using 1.5mm² (16 AWG) for all three conductors. The switches are either switching contactors or a DC relay using 0.75mm² (18 AWG) wire. Entire board is 240V AC with 12V DC for some control switching. Indicator lamps are 240V LED panel lamps.

The switch gear and connection system. All DIN rail mounted and wired using 4mm² and 2.5mm² stiff house wire. All screw terminals are using crimped lugs.

• Starting from the left side with power input from the isolator into a 63A 30mA residual current device as the dedicated feed is not RCD protected at the house board.
• From the RCD, the power is fed through a 25A contactor switched by doug's normally closed pump and element switch protection design.
• From the contactor power is fed to the ABB 4mm² spring connectors for distribution.
  • A 4mm² circuit feeds via the 20A fuse to the 25A kettle contactor.
  • A 2.5mm² circuit feeds via the 2A fuse to the pump and instrumentation/control devices.
• The kettle live wire feeds from the contactor through a 30A CT to a 50A 240V SSR. Went for way overrating on the SSR, and all the wiring for safety margin and possible future expansion.
• 4mm² flexible wire from the SSR to the IEC 60309 socket along with matching neutral and 2.5mm² earth line.
• The 2A circuit feeds a 12V DC switch mode PSU and a 10A 240V relay for the pump. Live testing of my magnetic pump gives max 0.5A load when pressure-locked.
• The pump switch controls the 12V DC coil on the relay and 2.5mm² wire will run to the IEC C13 socket.

Anything obvious that I've missed? Besides the floating 12V DC PSU which is waiting for a 3D-printed DIN mount. Backplane grounding is done via the ABB ground block which grounds the DIN rail and the mounting screws.

Beauty shot of the inside of the panel. Pay no attention to the temporary wiring nightmare. Waiting for delivery on some plug-in screw terminals to assemble the control wiring harnesses to allow for the disconnection of the front panel controls when opening the board.

Tested overnight and the beast is alive and kicking.

 

[bruce_the_loon]

The panel is now functionally and aesthetically complete. Still fiddling with getting the Raspberry Pi to drive the SSR, but that awaits hardware to be delivered.

First the front panel with all the indicators, switches and labels in place.

Next the inside of the front panel with the wiring harness completed and wired to the plug-in connectors.

Then the inside of the panel showing the DIN rail with all the components wired in place, wiring secured and ready to go.

Finally a shot of the beast in operation firing the kettle.

 

[bruce_the_loon]

Here is the as-built wiring diagram. Grabbed and modified from one of @doug293cz's as mentioned earlier.

Edit: Fix missing link between pump and kettle switch on safety interlock circuit.
Edit 2: Correct grounding connection per doug's comment.

 

[bruce_the_loon]

New wiring diagram after finding out the high current driver module on the Pi is a sink, not a source and I need to put it on the negative lines of the SSR and relay.

Edit: Correct grounding connection per doug's comment.

 

[doug293cz]

You should not be switching the ground with the main power contactor. Ground should never be switched. It's not necessary to switch the neutral, but ok to do so.

Brew on

 

[bruce_the_loon]

You should not be switching the ground with the main power contactor. Ground should never be switched. It's not necessary to switch the neutral, but ok to do so.

Brew on

I've updated the diagrams to not switch the ground line.

I ended up using the 3rd pair of contacts on the rotary isolator to join the external ground line to the internal wiring to avoid installing another connector in a tight corner. I'll either bridge the two screw terminals externally or transfer both wire connectors to the same screw terminal on the isolator.

 

[RufusBrewer]

I have to say, that schematic confuses me. You have switches that are serial, one switch feeds the next switch.

You start off with two switches that feed main switch that turns on the 25 amp contactor. I count 4 things that have to be closed before you can do anything.

If I am reading the cinematic correctly, thr pump switch must be on for the kettle to be on. Why? I would have them be independent if each other.

I would increase the 2 amp fuse that feeds the pump and 12 VDC PS. In my min, fuses in the box are to protect against shorts. You do not want to be opening the box and replacing fuses in the middle of you mash. Use as as high as a value as is safe.

 

[bruce_the_loon]

Let's see if I can clarify the schematic.

The first set of contacts is a rotating manual isolator that shuts the entire panel down. Immediately following that is a 2 pole residual-current device (our name for a GFCI) providing in-panel ground fault protection as the power source is not ground fault protected. Unless there is a ground fault, the breaker remains permanently closed as does the 2A fuse disconnector. So under normal circumstances, only the isolator and the main key switch need to be operated for the panel to be fully powered.

The pump and kettle switches are dual contact switches, one set of contacts (the bottom contacts in the schematic) are normally closed that are chained together to ensure that the main contactor cannot be activated if the pump or kettle switches are in the On position.

The other set of contacts are normally open and the two sets are fully separate. The NO contacts on the pump switch are connected to the 12V DC supply to activate the pump relay coil. The NO contacts on the kettle switch are connected to the 240V AC from the 2A pump/PS circuit to activate the contactor.

The fuse is a valid concern although I am pretty sure that the 2A is sufficient for the operation. From what I have measured, the pump and other draws on that fuse are cumulatively at 1.1A. Naturally I will curse and swear when I'm proved wrong.