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09/28/2020 9:48 AM
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Wiring Diagram Check
CharcoalRoaster
Hi everyone, I'm finalizing the wiring for my new FB build. I've been working off of various diagrams that have been posted on here before. I believe I've got things correct. If I do, then I'll connect everything to the TC4 and fire it up for a test roast.

Would you guys be willing to have a look over to see if I overlooked anything or have something miswired in a dangerous fashion?

Thank you!

<<< FYI >>>

(1) Dotted line = Neutral
(2) I'm using Buss Bars because I have a couple of other things I'm running off of the 120v Line-In
CharcoalRoaster attached the following images:
element_2.jpg vac.jpg
Anot
Hi! I'm not that good with electronics but am reacting to a few things so make sure to wait for ppl with more knowledge to answer. Im commenting your first picture only - the second one I dont really understand, have never connected a SSR to a motor.

Only the live wire should be connected to the SSR - having it connected as is displayed in the pic would make the heating element constantly on (when the switch is on) as nothing prevents the current to follow the path through live side to neutral side and back. Only the live wire goes into the SSR, and is connected to one of the terminals on the AC side, the other AC terminal on the SSR is connected to the heating element. The neutral wire should go directly to the heating element.

The SSR is essentially a very fast on/off switch that is controlled by input from the microcontroller by turning off and on the connection between the two terminals on the AC side. Hope that explains it.

Looking forward to seeing your project!
renatoa
Anot is right, you risk a big boom on the SSR when sending the first heater command from TC4, because the SSR will short the mains, as is connected in first picture.

So, disconnect neutral line (black) from SSR 1, but keep it connected to the heater.
Disconnect the red line from SSR 2, and move it to SSR 1, that remains unconnected after removing the black line. Keep the red line coming from SSR2 to the heater.
You are good now.

In the second picture, again you might commit a mains short, depends... not sure what are the black squares labeled as ZCD AC Input Load/Input. Single connections or a pair, that carry both the line and neutral ?
Even so, again SSR is not connected right, it have to be in series with the continuous line that comes from ZCD to the motor. So, remove line from SSR 2 to ZCD Input, and connect instead the line that comes from ZCD Load, that in current schema is connected to SSR 1.
Edited by renatoa on 08/22/2020 2:39 AM
CharcoalRoaster
I'll read both replies more closely in a little bit but a couple points of clarification ...

I am running a US 240v so there is no neutral line on the first diagram connected to the SSR. Both lines coming in are 120v legs. If I hear you right then I need to run one leg straight from breaker to heater instead of connecting it to one of the SSR terminals, correct?

On my ZCD it has to blocks
(1) AC Input with a Line and Neutral connector
(2) AC Load with a Line and Neutral connection
renatoa
Correct for the first paragraph. A SSR is a circuit breaker, so should be connected in line, as any switch or fuse.

Second, with your clarification about the ZCD connections, the good news: you don't have a short, but rewiring still required, as I wrote, to place SSR in series with motor.
CharcoalRoaster
Ok, question about the first paragraph again -- if one hot 120v leg is running direct to the heater then won't the heater be operational as soon as there is power potentially causing a burnout of the element?

And to clarify, for the second diagram AC Line-In and AC Load Line should be connected together?

Like this?
CharcoalRoaster attached the following images:
blower_3.jpg element_3.jpg

Edited by CharcoalRoaster on 08/22/2020 8:48 AM
renatoa
Well, seems I didn't worded it right, enough for a good image, my bad... so attaching the right wiring, for the ZCD case.

Nope, the heater is not operational with only one wire powered, you need both to close the circuit.
This is true assuming the heater is 100% insulated between the green wire (tin housing), and any of the black/red lines.
If green has contact with either red or black terminals, then we have the potential for a big trouble...
renatoa attached the following image:
vac_1.jpg
CharcoalRoaster
Ok thanks Renatoa, this makes much more sense to me now.

Yes, on the heater element enclosure there is ceramic insulation surrounding the heating coil. Is there a better/safer way to ground the 240v Ground Wire coming in from the main?
renatoa
Better than the house grounding ? You have doubts about it has been done at the standards? Or your installation has no grounding at all ?

You might consider connecting the ground terminal to a water pipe, if you answer Yes to any of the questions above.
CharcoalRoaster
Sorry, let me clarify...

The 240v source is a Nema L14-30 receptacle in my garage (4 wire -- H,H,N,G). I have an extension cord that plugs into that receptacle then runs into my roaster. The 2 Hot legs terminate as seen in the wiring diagram. Since I do not need the neutral that's why I have it terminated in a wire nut. The ground coming into the roaster doesn't have a buss or anything to terminate to like the 120v course seen in the blower diagram.

I'm being careful and cautious while trying to set this up safely and properly. I appreciate the advice as I attempt to do so.ThumbsUp
mg512

Quote

renatoa wrote:

Well, seems I didn't worded it right, enough for a good image, my bad... so attaching the right wiring, for the ZCD case.

Nope, the heater is not operational with only one wire powered, you need both to close the circuit.
This is true assuming the heater is 100% insulated between the green wire (tin housing), and any of the black/red lines.
If green has contact with either red or black terminals, then we have the potential for a big trouble...


I haven't used a ZCD before myself, so I might be wrong, but are you sure the ZCD should be connected in series with the heatere and SSR? I would assume it has to be connected in parallel, between Live and Neutral. (edit: I had written Ground when I mean Neutral.)
Edited by mg512 on 08/23/2020 8:38 AM
https://www.tindie.com/products/15798/
lil_roasty
Maybe this will be of some use - here's the schematic for the roaster I've been building recently. Yours will be a bit different because the 240v vs I used two 120v circuits for heater and blower, but the same ideas apply. Where I have neutral, you would have the other hot. I've also attached a useful diagram of 240v signal - as you probably know it's basically two 120v signals that are 180 degrees out of phase. My diagram isn't 100% accurate, I have the ZCD also connected to AC via the 2-pole switches.

Your recent heater/blower diagrams look pretty good, except the ZCD is wired incorrectly. You should have one of the AC input poles to either hot, and the other to neutral. Technically you could put it between both hots and I believe the result would be the same since the zero-crossing points are the same. Given that it's equivalent I'd probably opt to go to neutral just to have a slightly lower voltage there.

Not sure if you are doing the same based on your diagram, but I have a RobotDyn dimmer module that I'm using for the ZCD circuit only. The "AC Load" terminals are disconnected and I'm using some Crydom D2425-10 SSRs instead of the built-in triac since the SSRs have a higher power rating. I wrote code to control the random-fire SSRs from my Teensy based on the ZCD signal.

In case you're not aware - it's very important that you use a "random-fire" SSR. Most "normal" SSRs have built-in zero-cross circuitry that will only switch the SSR on at zero-crossings. A random-fire SSR allows you to switch the SSR on at any time, but once turned on it will stay on until the next zero-crossing, at which point it turns off until triggered again. I've attached a useful graphic for understanding the trigger signal and resulting AC waveform that you want. The percentage power is controlled by how long after the zero-crossing you wait to send the SSR trigger pulse. You don't need to keep the logic trigger "high" very long, just long enough to latch the SSR - I use 300 microsecond pulse signals.

You could do a slower PWM with normal SSRs but I'm not about that life (and the blower probably wouldn't appreciate that).
lil_roasty attached the following images:
coffee_schematic2.jpg figure_2-240v-1.png ecmweb_com_sites_ecmwebcom_files_uploads_2015_01_leading_edge.png
lil_roasty

Quote

I haven't used a ZCD before myself, so I might be wrong, but are you sure the ZCD should be connected in series with the heatere and SSR? I would assume it has to be connected in parallel, between Live and Ground.


Note: While technically you could connect the ZCD between live and ground, you should not purposefully connect any power electronics to ground. You should use neutral in place of ground. Ground is mostly for protecting against shorts. Neutral is for carrying current.

I use GFCI plugs on my roaster as a safety measure - they will very quickly break the circuit if any current is being drawn from live but not returning to neutral. Useful if you accidentally stick a finger where it shouldn't be stuck (but not foolproof, if you short neutral to live with your body the GFCI will not trigger).
renatoa

Quote

mg512 wrote:


I haven't used a ZCD before myself, so I might be wrong, but are you sure the ZCD should be connected in series with the heatere and SSR? I would assume it has to be connected in parallel, between Live and Ground.


Actually, it is in parallel, electrically... the terminals are connected together, to bypass the power and no other transformation.
The terminals are different, and labelled as Input and Load, just to ease understanding of logical flow, and provide enough connection points for the wiring, but they are parallel on PCB.
renatoa

Quote

lil_roasty wrote:

In case you're not aware - it's very important that you use a "random-fire" SSR. Most "normal" SSRs have built-in zero-cross circuitry that will only switch the SSR on at zero-crossings. A random-fire SSR allows you to switch the SSR on at any time, but once turned on it will stay on until the next zero-crossing, at which point it turns off until triggered again.


I read this for many times, and each time it make me wonder if this is really true, or a misunderstanding launched at a moment in a forum by some guru, and cascaded from there countless time...

What I mean... I am automation engineer for (too) many years, and until recently, when I read this in a coffee forum, I wasn't even aware there exists on the market SSR having the ZCD function embedded ! I have to search some catalogs to convince me this is real, but still, they aren't listed as "normal" SSR, but... "exotic" Grin

Having some ten years of hi-edu experience (in computers, not automation), and part of a team who implemented automation systems of the greatest Hydro dam on the Danube, I can tell you that in all our courses, and on all our markets, the SSR that can be found are just random, and nothing else. And schematics are done accordingly.
Who needs zero cross... then provide a ZCD separately, because there simply there isn't offering for ZC SSRs on the industrial power electronic market. As far as I know...

This was a rant, not a critique :) US market could be different... but eBay.com SSR offering tell the same story as me Grin
Edited by renatoa on 08/23/2020 9:30 AM
lil_roasty

Quote

What I mean... I am automation engineer for (too) many years, and until recently, when I read this in a coffee forum, I wasn't even aware there exists on the market SSR having the ZCD function embedded ! I have to search some catalogs to convince me this is real, but still, they aren't listed as "normal" SSR, but... "exotic" Grin


You might be right there - had to look again but I think the zero-crossover switching feature is indeed an add-on not the norm. I think my perspective was skewed by looking at Crydom datasheets which make it sound like random-fire was the optional feature, plus reading a few posts on here. I definitely can't speak to the relative frequency of these devices in the wild.

In any case, just avoid the zero-crossover feature ThumbsUp
mg512

Quote

lil_roasty wrote:

Quote

I haven't used a ZCD before myself, so I might be wrong, but are you sure the ZCD should be connected in series with the heatere and SSR? I would assume it has to be connected in parallel, between Live and Ground.


Note: While technically you could connect the ZCD between live and ground, you should not purposefully connect any power electronics to ground. You should use neutral in place of ground. Ground is mostly for protecting against shorts. Neutral is for carrying current.

I use GFCI plugs on my roaster as a safety measure - they will very quickly break the circuit if any current is being drawn from live but not returning to neutral. Useful if you accidentally stick a finger where it shouldn't be stuck (but not foolproof, if you short neutral to live with your body the GFCI will not trigger).


Ah, yes, sorry, I meant Neutral of course. I'm used to thinking about DC systems where Ground is the neutral reference point, plus outside the US the protective "Ground" in AC systems is usually referred to as "Earth".

Yes, definitely use GFCIs for any DIY devices (or anywhere really!). A good general rule is also: If there's even the slightest chance that there might be live mains AC anywhere, only work with one of your hands, and keep your other hand in your pocket. That way you reduce the risk of the worst case scenario: Touching live with one hand and neutral with the other and having 110V / 230V across your torso.



Quote

renatoa wrote:

Quote

mg512 wrote:


I haven't used a ZCD before myself, so I might be wrong, but are you sure the ZCD should be connected in series with the heatere and SSR? I would assume it has to be connected in parallel, between Live and Ground.


Actually, it is in parallel, electrically... the terminals are connected together, to bypass the power and no other transformation.
The terminals are different, and labelled as Input and Load, just to ease understanding of logical flow, and provide enough connection points for the wiring, but they are parallel on PCB.


Ah, I missed the dashed lines. I think this is still not entirely accurate though, as far as I know most ZCDs, at least the ones that were made for the original TC4, only come with a single AC terminal. That terminal you would then connect directly to Live and Neutral, to be clear.

edit: Unless Charcoalroaster is actually talking about a PWM AC dimmer module, but in that case you would not need an SSR for the fan.
https://www.tindie.com/products/15798/
CharcoalRoaster
mg512 -- this is the component that I am using currently. https://www.ebay.com/itm/PWM-AC-Light...08a7cf1245
mg512

Quote

CharcoalRoaster wrote:

mg512 -- this is the component that I am using currently. https://www.ebay.com/itm/PWM-AC-Light...08a7cf1245


Ohhh, okay, yeah, that is not a ZCD, it's a PWM AC dimmer. It does have a zero-cross detection circuit on board, but it does not send the zero-cross signal back to the Arduino like a ZCD would. Instead, it essentially has a random-fire SSR on board itself! The Arduino only needs to send a PWM signal, and the dimmer board handles all the zero-cross detection and switching the AC signal at the right time. You do not need any SSR (random-fire or otherwise) for the fan if you're using this. Instead, you connect AC INPUT on the dimmer module to live and neutral from your mains AC, AC LOAD to the fan, and the VCC / PWM / GND header to the IO3 header on the TC4 / TC4+.
https://www.tindie.com/products/15798/
lil_roasty

Quote

CharcoalRoaster wrote:

mg512 -- this is the component that I am using currently. https://www.ebay.com/itm/PWM-AC-Light...4296306004


That lists a 2 amp long-term max current, so unless your blower pulls less than 480W I wouldn't recommend using it.
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