Starting an Electric Brew control panel for AG brewing

[sjp770]

So... I have two dead panel meters..

 

[sjp770]

I hooked up the meters as they were supposed to be connected. I think the repaired lm317 is now dead.. At least it only wants to put out 10v. Hoping the other one is OK.

There was a point raised by the Electric brewery people that you could run both off the same power supply or the panels would blow but I actually managed to blow both separately!

I got the volts out from the LM317 down to 5v and hooked up the Ammeter. All good. Hooked it up to the shunt (disconnecting power each time I opened the panel). Turn it on, Bang! tripped circuit and a dead ammeter.

Did the same with the Voltmeter off the other power supply, ran by itself fine, hooked it up to hot and neutral and Bang, same thing but no circuit trip this time.

There must be something weird like a potential difference? I dont know but I do know I now need 2x more meters..

EDIT: Maybe it was a DC shunt.. .I had a few lying around. Is there a difference?

 

[Crouch]

Man that sucks .. I have no useful input though, my electronic capabilities extend to putting the knife into the toaster to get my bread out ... and here I am trying to build an electric control panel!! I'll be wearing rubber gum boots when I start wiring mine up!

 

[sjp770]

$43 down the drain

So hold off following in my footsteps and copying the transformers for now.

I'll forge ahead tomorrow and try to get the PID's and Timer online. I need some smaller forky spade termination thingo's for the timer and bigger ones for the 4mm wire i'll use for the elements. I also need bigger ring terminals for the earth pole.

 

[Crouch]

$43 down the drain

So hold off following in my footsteps and copying the transformers for now.

I did a search for 'door bell transformers' (as per Kals build) on ebay.com.au and got dididly squat ... I don't expect this to be easy, but the end-goal will be an enjoyable one.

 

[sjp770]

I asked the question over there why the separate transformers and the answer was pretty much "because the instructions say so" and "if you dont do it this way the meters blow up"

Not once did someone actually say something useful like, "The transformers dont share a common ground as they dont have a grounding lead, so you can end up with a ground potential difference which is dangerous" (not true at all but the sort of answer i'd expect.)

I would love to have one power supply and a smarter protection circuit.

 

[gava]

I hooked up the meters as they were supposed to be connected. I think the repaired lm317 is now dead.. At least it only wants to put out 10v. Hoping the other one is OK.

There was a point raised by the Electric brewery people that you could run both off the same power supply or the panels would blow but I actually managed to blow both separately!

I got the volts out from the LM317 down to 5v and hooked up the Ammeter. All good. Hooked it up to the shunt (disconnecting power each time I opened the panel). Turn it on, Bang! tripped circuit and a dead ammeter.

Did the same with the Voltmeter off the other power supply, ran by itself fine, hooked it up to hot and neutral and Bang, same thing but no circuit trip this time.

There must be something weird like a potential difference? I dont know but I do know I now need 2x more meters..

EDIT: Maybe it was a DC shunt.. .I had a few lying around. Is there a difference?

I questioned why you'd even want these AMP and VOLTS meters in, I'm not sure about you but when I'm brewing I'm not monitoring what my amps/volts are doing I'm more about the temperatures and times.
I can see it looks cool on the panel but there's no real advantage.
I always thought the electric brewery guy put them in so it would make the panel look more even, maybe I'm missing something.

-Gav

 

[TheWiggman]

I've looked through this thread and can't find a circuit diagram. Can you put it up? And if you don't have one, that would be the first thing I'd do before doing anything else.
I agree that monitoring voltage and current isn't required. But the holes are there already so it'd be nice to have them filled with working meters.

 

[sjp770]

The holes are there now so I have to replace them. I like the idea of having the volts and more importantly the amps up on the panel.

It very well could have been something stupid I did, having based the wiring of their site. I have mounted the relay the correct way up but their diagram its upside down so I have all the wires on the wrong side(left and right are swapped) but it should still behave the same.

The ammeter I don't understand but there could have been something weird with the volt meter. As a precaution hooked up its wiring and then used a multimeter to check the voltage. I got a weird reading of 32v instead of 239v but as it was in range on the meter I hooked the meter up to verify. Bang.


Could anyone see the real reason you wouldn't run both off the one power supply?

 

[jonnir]

How did you hook them up?

 

[sjp770]

So it sounds like the mixup on the shunts may have killed the ammeter, and the instructions on the electric brewery may have lead me to connect the volt sensor neutral to a reply leg of the relay. Both meters arced from the DC pins to the ac monitoring side.

At this stage I'd love suggestions of higher quality meters that fit in 3 & 1/2" holes.

 

[sjp770]

Let's try this again

 

[Crouch]

I'd leave it just like that! Full industrial, rough and ready look.

 

[sjp770]

I think I will paint it still, im going to wait until the paint is at least 20c before i attempt it again, it was so think last time and having the textured original paint underneath didn't help. As I was removing it you could see it had never really set either, it was like taking off rubbery glue.

I'm also going to move the active and neutral rails further apart, probably by pushing the neutral down and shifting the shunt down, more like the original design. I didn't put enough though into the cables coming out of the power rails.

 

[sjp770]

Picked up the JB cold weld for $12.99 at Masters. They also had a larger pack there for $38 with 140mls in each tube if anyone want to know such things..

I will glue the heating element box tonight, assembling it tomorrow. One of the issues I have is the ridge on the keg.

 

[TheWiggman]

Sorry to be this bloke but...
If you're blowing meters because you're following the directions on the web site then in my opinion it's time to call in an electrician.

If you are an electrician then my apologies. It's just I get nervous when I see wiring without a full circuit diagram and blown components.

Ed: looked into this a bit more, there's no way you should be blowing ammeters across a shunt. The power source for them (low volt DC) is independent of what's being measured, which is across the shunt. Something's amiss, see a pro, never regret it.

 

[sjp770]

Well the mixed up shunt wasn't my fault, they look the same and I was certain they were all the same. As for the othone I metered out and got a bad reading, it was my fault I blew the volt meter as I didn't rectify it before hooking it up, just trusting a 30vac reading was within the range of the meter and not figuring out what was actually wrong.

From here on in I'm not going to trust the guides and follow them blindly, I'll make sure i understand each step first. One of the things I need to fix is I was looking at the 120v diagram but I'm not sure if anything changed.

 

[sjp770]

Don't mind you saying so by the way, I've been talking to an electrical engineer about what the issues were. I'm still concerned as to why there is a need for two independent power supplies for the two meters, in my mind you should be able to power both off a 5vdc power supply in parallel if there is enough current.

Both meters had a resistor or similar SMD size chip connecting the negative leg of the DC circuit to the metered side, this is what blew. Even if it was a diode, why should they be connected at all?

 

[TheWiggman]

From here on in I'm not going to trust the guides and follow them blindly, I'll make sure i understand each step first.

Good. Understanding it is really important. Also remember US use 60 Hz too but most industrial units cater for both sides of the world. Shunts, relays and the like though... different story.
I quote from experience on this one. I've given myself 2 x 240V boots and don't recommend it. Most electrical stuff is simple really but electricians have one thing I don't - experience. It's the things you don't know that you don't know will catch you out.
I'm quite surprised theelectricbrewery put the instructions in the format they do, they're opening themselves up for liability listing clear instructions on how to wire AC equipment.

Ed: I misunderstood power supplies. Seems the AC and DC share a ground in the voltmeter. Just have to take their word for it I suppose.

 

[TheWiggman]

Trying not to sound like a precocious knob, finding it hard. If anyone wants me just call out for dad.