Exploded SSR / Loud Pop / PLEASE HELP

[r8rphan]

BTW, I really don't know how the PID is wired, and won't until I get one in my hands, but one possible use where a contactor would be handy (and add some sexy), is if what Casey said is true, and the alarm contacts on the PID are nothing more than an isolated switch, then you could use momentary on off push button switches to energize the contactor and the use a holding loop where the alarm contacts were in series with the off push button in the holding loop... Both the alarm contacts, and 'off' push button would need to be normally closed contact though.. and I'm really not sure how the alarm contacts are configured (they need to be of the rated voltage used too).. The 'on' push button would be configured normally open..

Put the contactor in series with the incoming 240v supply circuit and then if the alarm circuit triggers, it shuts power off to 'everything'... Just like the off push button would..

just a thought...

 

[Firewalker11]

Ummm, YES!...

Read what I said again.. I said 'difference' between what goes out and what comes back.. not current 'through' (which is what the standard breaker part itself measures)

This is 'indeed' how it works.. 'ground' is generally where the missing current goes. but it can go elsewhere, like another circuit.. Which is why it compares out to return and not to ground...

It is entirely possible to become part of a supply circuit to something outside of the supply circuit that is not ground.... and this is why they compare return to what went out..

STEEEERIKE 2!

Nope, "'ground' is generally where the missing current goes" is not correct. A GFCI can fail spectacularly with all sorts of effects! If you have never visited his site, Mike Holt has all sorts of great, practical explanations about how stuff works etc.

Understand that you can "over-amp" a GFCI and not break the connection or induce a differential to ground to trip it. That is why you still have to use a circuit breaker, it protects against overload.

G-Ground F-Fault C-Circuit I-Interrupter, no load protection natively.

 

[Firewalker11]

BTW, I really don't know how the PID is wired, and won't until I get one in my hands, but one possible use where a contactor would be handy (and add some sexy), is if what Casey said is true, and the alarm contacts on the PID are nothing more than an isolated switch, then you could use momentary on off push button switches to energize the contactor and the use a holding loop where the alarm contacts were in series with the off push button in the holding loop... Both the alarm contacts, and 'off' push button would need to be normally closed contact though.. and I'm really not sure how the alarm contacts are configured (they need to be of the rated voltage used too).. The 'on' push button would be configured normally open..

Put the contactor in series with the incoming 240v supply circuit and then if the alarm circuit triggers, it shuts power off to 'everything'... Just like the off push button would..

just a thought...

As long as you pick a contactor that will operate on the alarm voltage.

 

[r8rphan]

As long as you pick a contactor that will operate on the alarm voltage.

I'm simply going by what Casey said that the alarm contacts, are just 'contacts' in which case you would be using the load voltage from one side of the contactor.. depending on the coil voltage of the contactor, this would be either 120v, or 240v...

If the PID supplies voltage to these contacts,, then this is different than what I understood Casey to be saying, and all bets are off...

Like I said, I really don't know anything about the various contacts of the PID, as I've never personally examined one.. But when I get one, I'll understand a lot more...

 

[r8rphan]

STEEEERIKE 2!

Nope, "'ground' is generally where the missing current goes" is not correct. A GFCI can fail spectacularly with all sorts of effects! If you have never visited his site, Mike Holt has all sorts of great, practical explanations about how stuff works etc.

Understand that you can "over-amp" a GFCI and not break the connection or induce a differential to ground to trip it. That is why you still have to use a circuit breaker, it protects against overload.

G-Ground F-Fault C-Circuit I-Interrupter, no load protection natively.

I was not referring to a device failure situation, but generally what happens when it is doing what it is supposed to...

Generally, when a person comes in contact with electricity and gets shocked, they become/create a circuit between themselves and ground.. Second most likely scenario is hot and neutral, third, would be separated load and line side of a neutral that is part of a balanced 3 wire system with the other circuit still energized (which would trip a GFI just by it's mere existence).. Other scenarios can be between hot and the neutral of another circuit than it's own, or hot and the other phase of a 240v system, or hot and the other phase connected to another circuit altogether..

As you can see, there are a lot of ways a person can become part of the circuit.. and the point I was making in explaining how a GFI works, is that if it only looked for a fault to ground, then it would only protect the person when they experience the first scenario.. becoming a circuit between hot and ground..


That's why it compares current flow in the 'two' conductors to each other.. to protect in almost all of the other scenarios I listed... and more...

Current is equal in all parts of a series circuit... So, unless it goes somewhere else outside of the circuit, what goes out should be the same as what comes back.. 2 amps in the hot leg = 2 amps in the neutral leg (or the other phase in a 240v circuit)

Think of it as a device with two ammeters, one in each of the current carrying legs.. It is constantly looking to see if the two ammeters are reading exactly the same.. How much is going through them is immaterial.. They must always be the 'same' as each other... That's what it measures..

If they are not the same, then that means something has 'tapped in' to the circuit and is finding another path to balance the circuit.. be it ground, an opposite phase on an uninvolved circuit, a neutral being used on a different circuit, whatever...

The only thing it can not detect, is if you become part of the circuit across the two legs it is monitoring/comparing.. Because then you are just a load like anything else, and current out still equals current return...

Does that help you to understand?

Device 'failure' is an entirely different subject.... and so is an over current protection device, or the over current protection part of the GFI...

Imagine a shunt trip device connected to a circuit measuring the difference between the ammeters.. if they are the same, then there is no differential, no trigger voltage, and no trigger for the shunt trip.... but if they are different, then a voltage divider network is created, the shunt trip circuit sees the voltage created by the differential, and triggers the shunt trip..

That is essentially what is happening....

 

[passedpawn]

Funny how all of the electrical discussions end up with a bunch of pissed off people that want to save a few bucks.

This discussion had NOTHING to do with money until you brought it up. It had to do with adequate design and safety. The switch used was perfectly adequate, and safe.

What are you talking about?

 

[passedpawn]

STEEEERIKE 2!

Stop trolling. The previous poster described a GFCI correctly.

You are not helping here. Check yourself.

 

[Firewalker11]

This discussion had NOTHING to do with money until you brought it up. It had to do with adequate design and safety. The switch used was perfectly adequate, and safe.

What are you talking about?

Gotcha, dissenters are not welcome.

 

[Firewalker11]

I was not referring to a device failure situation, but generally what happens when it is doing what it is supposed to...

Generally, when a person comes in contact with electricity and gets shocked, they become/create a circuit between themselves and ground.. Second most likely scenario is hot and neutral, third, would be load and line side of a neutral that is part of a balanced 3 wire system with the other circuit still energized (which would trip a GFI just by it's mere existence).. Other scenarios can be between hot and the neutral of another circuit than it's own, or hot and the other phase of a 240v system, or hot and the other phase connected to another circuit altogether..

As you can see, there are a lot of ways a person can become part of the circuit.. and the point I was making in explaining how a GFI works, is that if it only looked for a fault to ground, then it would only protect the person when they experience the first scenario.. becoming a circuit between hot and ground..


That's why it compares current flow in the 'two' conductors to each other.. to protect in almost all of the other scenarios I listed... and more...

Current is equal in all parts of a series circuit... So, unless it goes somewhere else outside of the circuit, what goes out should be the same as what comes back.. 2 amps in the hot leg = 2 amps in the neutral leg (or the other phase in a 240v circuit)

Think of it as a device with two ammeters, one in each of the current carrying legs.. It is constantly looking to see if the two ammeters are reading exactly the same.. How much is going through them is immaterial.. They must always be the 'same' as each other... That's what it measures..

If they are not the same, then that means something has 'tapped in' to the circuit and is finding another path to balance the circuit.. be it ground, an opposite phase on an uninvolved circuit, a neutral being used on a different circuit, whatever...

The only thing it can not detect, is if you become part of the circuit across the two legs it is monitoring/comparing.. Because then you are just a load like anything else, and current out still equals current return...

Does that help you to understand?

Device 'failure' is an entirely different subject.... and so is an over current protection device, or the over current protection part of the GFI...

Imagine a shunt trip device connected to a circuit measuring the difference between the ammeters.. if they are the same, then there is no differential, no trigger voltage, and no trigger for the shunt trip.... but if they are different, then a voltage divider network is created, the shunt trip circuit sees the voltage created by the differential, and triggers the shunt trip..

That is essentially what is happening....

Yes, agreed!

Back to the topic at hand, adequate design and safety IMHO, should include a contactor.

Better?

 

[passedpawn]

Gotcha, dissenters are not welcome.

Trolls not welcome. You're inventing arguments. Take a break.

 

[caseyw]

I'm simply going by what Casey said that the alarm contacts, are just 'contacts' in which case you would be using the load voltage from one side of the contactor.. depending on the coil voltage of the contactor, this would be either 120v, or 240v...

If the PID supplies voltage to these contacts,, then this is different than what I understood Casey to be saying, and all bets are off...

Like I said, I really don't know anything about the various contacts of the PID, as I've never personally examined one.. But when I get one, I'll understand a lot more...

If the cartoon in the original post is a representation of the physical connections of the controller, then the alarm is just a set of contacts, in which case your interpretation of what I wrote is correct.

 

[crane]

You have 5500 Watt lights in your house?

No, but a light bulb is a load and you stated you wouldn't use a switch to power a load. So what you are implying is that at some point of power consumption there is a cutoff where you should not use a switch and instead use a contactor regardless of whether the switch can handle that load or not? Can I ask what this magic number is?

 

[caseyw]

No, but a light bulb is a load and you stated you wouldn't use a switch to power a load. So what you are implying is that at some point of power consumption there is a cutoff where you should not use a switch and instead use a contactor regardless of whether the switch can handle that load or not? Can I ask what this magic number is?

It's a good question - one that I don't really have an answer for. If someone twisted my arm and said I had to pin it down somewhere, I'd probably not want to manually switch more than about 500 watts. Less if the voltage gets higher.

Again, this is only about my personal acceptable level of risk. I'm perfectly Ok switching on the light switch. Switching on 5500 watts? Ehh.... no thanks

You guys ever take electrical safety? Arc flash training? I'd take an NFPA 70E (?) I think it is... training class. Puts a healthy fear of electricity into you.

 

[passedpawn]

It's a good question - one that I don't really have an answer for. If someone twisted my arm and said I had to pin it down somewhere, I'd probably not want to manually switch more than about 500 watts. Less if the voltage gets higher.

Again, this is only about my personal acceptable level of risk. I'm perfectly Ok switching on the light switch. Switching on 5500 watts? Ehh.... no thanks

You guys ever take electrical safety? Arc flash training? I'd take an NFPA 70E (?) I think it is... training class. Puts a healthy fear of electricity into you.

You might not be the only person with experience with electricity here.

 

[caseyw]

You might not be the only person with experience with electricity here.

Sorry. I will politely bow out of the discussion.

 

[brandonring]

Thanks for all the discussion guys. Even the unnecessarily aggressive ones. I'm guessing there's always room for improvement and sharing of ideas/opinions in such a dangerous field.

 

[r8rphan]

You are fine running any load through a device up to 80% of rated load.. Above that, you are technically violating code...

So a 15A switch is fine up to 12A (basically up to about 1400 watts) and it should last for quite a while...

Same with a receptacle... But be careful how receptacles upstream in the circuit are wired.. If they are through wired instead of pigtailed, then whatever you plug in down stream from them has to flow through the receptacle.. This is what causes kitchen fires, especially if the through wiring is stabbed in.. Stabbed in wiring on switches is also problematic.. I don't do it, I pigtail everything, and then side wire all devices...

So a 5500 watt heater element draws 24.9A, which is 80% of 29.9A... So with a 30A switch you are right up against the limit...

They make motor rated switches by horsepower which look the same and can handle more.. But the thing is, that 5500w is not a continuous load, It rarely runs at that power for extended periods.. The PID controlled relay should be operating at a reduced duty cycle.. and if you are worried about it in manual mode, just run it at something less than 100%.. like 85-90% and then you have plenty of breathing room...


FYI, when sizing wire, calculate the max 'continuous' load and multiply by 1.25... The result of that is how you size your wire according to NEC table 310-16.. Your breaker is sized to the wire.. If no corresponding breaker size exists for your rated wire current, then you are allowed to go up to the next common size...

For instance #6 THHN is rated at 75A.. You can use an 80A breaker on it because 75A breakers do not exist...

 

[FuzzeWuzze]

Hmmm

 

[NoIguanaForZ]

Um.... No?

A GFCI is measuring current to GROUND, its not a amperage rated circuit breaker.

A GFCI is detecting current "lost" to ground. Generally speaking, this is most salient when the current is being "lost" because the operator has inadvertently placed him/her/themself in series with ground.

So the original statement that a GFCI would remove most of the danger is correct.

(It wouldn't help if you'd grabbed the red and black wires, though).

 

[brandonring]

I threw back a few delicious Tree House beers last night and came up with this diagram. It looked better to me last night but here she is in her cluttered glory. Round 3.

I still have the neutrals switched because I currently have easy access to the double pole rocker switches. I'm still kinda in the dark (pun intended) when it comes to the lights. Am I getting closer?

 

[Firewalker11]

A GFCI is detecting current "lost" to ground. Generally speaking, this is most salient when the current is being "lost" because the operator has inadvertently placed him/her/themself in series with ground.

So the original statement that a GFCI would remove most of the danger is correct.

(It wouldn't help if you'd grabbed the red and black wires, though).

Perhaps I can piggyback on your post? I was looking at this GFCI issue solely from the ability of the GFCI to work as an heat or amperage breaker due to the load being controlled by a light switch.

I agree 100% that a GFCI is essential in this circuit and all, I just read into it that it would also act as a circuit breaker under overload conditions.

Sorry I didn't clarify and that I came off as a troll. I had no intention of doing so.

Thanks NoIguanaForZ for your insite.

 

[dyqik]

You are fine running any load through a device up to 80% of rated load.. Above that, you are technically violating code...

So a 15A switch is fine up to 12A (basically up to about 1400 watts) and it should last for quite a while...

Same with a receptacle... But be careful how receptacles upstream in the circuit are wired.. If they are through wired instead of pigtailed, then whatever you plug in down stream from them has to flow through the receptacle.. This is what causes kitchen fires, especially if the through wiring is stabbed in.. Stabbed in wiring on switches is also problematic.. I don't do it, I pigtail everything, and then side wire all devices...

So a 5500 watt heater element draws 24.9A, which is 80% of 29.9A... So with a 30A switch you are right up against the limit...

They make motor rated switches by horsepower which look the same and can handle more.. But the thing is, that 5500w is not a continuous load, It rarely runs at that power for extended periods.. The PID controlled relay should be operating at a reduced duty cycle.. and if you are worried about it in manual mode, just run it at something less than 100%.. like 85-90% and then you have plenty of breathing room...


FYI, when sizing wire, calculate the max 'continuous' load and multiply by 1.25... The result of that is how you size your wire according to NEC table 310-16.. Your breaker is sized to the wire.. If no corresponding breaker size exists for your rated wire current, then you are allowed to go up to the next common size...

For instance #6 THHN is rated at 75A.. You can use an 80A breaker on it because 75A breakers do not exist...

I think this bears repeating loudly: As you say in the middle, the 80% derating is for _continuous_ loads only, defined as lasting over 3 hours. So derating doesn't apply to typical brewing operations.

You are fine running 14A through 15A switch and a 5500W element on a 30A switch and circuit in the likely use case here.

 

[doug293cz]

BTW, I really don't know how the PID is wired, and won't until I get one in my hands, but one possible use where a contactor would be handy (and add some sexy), is if what Casey said is true, and the alarm contacts on the PID are nothing more than an isolated switch, then you could use momentary on off push button switches to energize the contactor and the use a holding loop where the alarm contacts were in series with the off push button in the holding loop... Both the alarm contacts, and 'off' push button would need to be normally closed contact though.. and I'm really not sure how the alarm contacts are configured (they need to be of the rated voltage used too).. The 'on' push button would be configured normally open..

Put the contactor in series with the incoming 240v supply circuit and then if the alarm circuit triggers, it shuts power off to 'everything'... Just like the off push button would..

just a thought...

The alarm on the MyPin TD4-SNR is an NO contact, so no-go with your idea.

In any case the alarm function in a mashing/boiling application is kind of worthless. You don't want to set the trip point below boiling (for mash mode), or you will have to reset the trip temp every time you switch between mash and boil mode. And, when would it ever trip if the trip temp was set above boiling?

That said, I do show how to wire an alarm in the schematic I'm about to post. But, I wouldn't bother with it.

Brew on

 

[Firewalker11]

I think this bears repeating loudly: As you say in the middle, the 80% derating is for _continuous_ loads only, defined as lasting over 3 hours. So derating doesn't apply to typical brewing operations.

You are fine running 14A through 15A switch and a 5500W element on a 30A switch and circuit in the likely use case here.

Does this also include the feeder wiring?

 

[doug293cz]

Here's my version of the design. It has a couple of extra features compared to OP's original design:

• Both "Element Power On" and "Element Firing" indicator lights
• A switched outlet for the pump, and an non-switched outlet for whaterver

I show the pump and PID power switches grounded. If there is not an obvious way to attach ground wires (depends on the switches used), then these connections can be omitted. If the controller is in a metal enclosure, then the enclosure also needs to be grounded. I would leave the alarm disconnected, for reasons stated previously. The alarm can be wired to a buzzer (shown), light, or combo lighted buzzer. A switch in series with the alarm indicator can also be convenient to enable/disable the indicator.

Any questions, just ask.



Brew on

 

[doug293cz]

...

So a 5500 watt heater element draws 24.9A, which is 80% of 29.9A... So with a 30A switch you are right up against the limit...

...

5500W @ 240V works out to 5500/240 = 22.9A, and 22.9/30 = 0.764. So, lots of margin here.

Brew on

 

[Gavin C]

Here's my version of the design. It has a couple of extra features compared to OP's original design:

• Both "Element Power On" and "Element Firing" indicator lights
• A switched outlet for the pump, and an non-switched outlet for whaterver

I show the pump and PID power switches grounded. If there is not an obvious way to attach ground wires (depends on the switches used), then these connections can be omitted. If the controller is in a metal enclosure, then the enclosure also needs to be grounded. I would leave the alarm disconnected, for reasons stated previously. The alarm can be wired to a buzzer (shown), light, or combo lighted buzzer. A switch in series with the alarm indicator can also be convenient to enable/disable the indicator.

Any questions, just ask.

View attachment 352608

Brew on

Over and above the call of duty on this last post Doug. Fantastic.

When I go electric, just a heads up, I'm going to be picking your brain mercilessly. Not on the horizon just now.

Thanks also the the many other learned and helpful contributors to this thread. A lot of it is greek to me but hopefully one day thanks in part to discussions like this I can reciprocate.

Tangent over. Back in my box

 

[doug293cz]

I threw back a few delicious Tree House beers last night and came up with this diagram. It looked better to me last night but here she is in her cluttered glory. Round 3.

I still have the neutrals switched because I currently have easy access to the double pole rocker switches. I'm still kinda in the dark (pun intended) when it comes to the lights. Am I getting closer?

This looks much better than your previous schematics.

The only problem is with your element firing light. It won't work the way you think it will. With the element power switch on, the light will be receiving 120V thru the element, which will cause it to light partially when the SSR is off. It will light at full brightness when the SSR is on. Better to use a 240V lamp wired between the two hots between the switch and elements.

You can either switch both the hots and neutrals, or just the hots. You don't have to use both sets of contacts on the switches. Not switching the neutrals reduces the total number of connections that need to be made (and can fail.) What you are not allowed to do is switch just the neutrals without switching the hots.

I prefer to put the element power switch for the hot line going thru the SSR between the power feed and the SSR, rather than after the SSR. This allows the use of both"Element Power On" and an "Element Firing" indicator lights. Also, cuts off power closer to the feed inside the panel. That said, many designs successfully put one side of the switch after the SSR.

Brew on

 

[brandonring]

Here's my version of the design. It has a couple of extra features compared to OP's original design:

• Both "Element Power On" and "Element Firing" indicator lights
• A switched outlet for the pump, and an non-switched outlet for whaterver

I show the pump and PID power switches grounded. If there is not an obvious way to attach ground wires (depends on the switches used), then these connections can be omitted. If the controller is in a metal enclosure, then the enclosure also needs to be grounded. I would leave the alarm disconnected, for reasons stated previously. The alarm can be wired to a buzzer (shown), light, or combo lighted buzzer. A switch in series with the alarm indicator can also be convenient to enable/disable the indicator.

Any questions, just ask.

View attachment 352608

Brew on

Doug you are amazing!

 

[doug293cz]

Doug you are amazing!

Thanks, and you're welcome. I do it because I enjoy it, and want to help where I can.

Brew on

 

[r8rphan]

5500W @ 240V works out to 5500/240 = 22.9A, and 22.9/30 = 0.764. So, lots of margin here.

Brew on

240v is not what is used for calculation.. The acceptable voltage range is 220v -240v... (110v-120v for 115v)..

So calculations are done using the 'ideal' target voltage of 230v.. That is what the generating plant seeks to deliver to your premises... Load on the system (or lack thereof), voltage loss due to long wire runs, etc. can affect the system voltage, both at delivery point, or at point of use... If you put a meter on your service, and watch it throughout the day, especially in summer months when all your neighbor's A/C is running (or your own), you'll see the voltage delivered to your service vary quite a bit....

That's why the code requires calculating voltage loss into your on site wiring... In most counties in Ca, they actually make you show it as part of your green sheet when installing a new service or upgrading an old one.. No more than 3% max voltage drop to any subpanel, 3% to point of use on the branch circuit from the breaker, 5% max total from service to point of use...


I made a typo in the first number (but not the second), as 5500/230 = 23.91304348 and that times 1.25 = 29.89130435... I rounded off, as there's not really much point in carrying it out 8 decimal places... Having installed 'hundreds' of residential services, I'm very familiar with all of this... and it's a royal PITA in general..


But we're splitting hairs here... The duty cycle of a PID controlled heater element will be significantly lower than 100% continuous load, and even in manual mode, you're not going to be running at max for that long before you back it off..

But if you're worried about it, just set it to something less than 100% and wait a couple minutes longer for it to get to boil... I personally, would not worry about it.. The 'worst' that is going to happen is a slightly reduced switch life..

Unless you wire the switch to short both hots together, then the switch life is gonna be 'significantly' shortened.. lol

 

[r8rphan]

Here's my version of the design. It has a couple of extra features compared to OP's original design:

• Both "Element Power On" and "Element Firing" indicator lights
• A switched outlet for the pump, and an non-switched outlet for whaterver

I show the pump and PID power switches grounded. If there is not an obvious way to attach ground wires (depends on the switches used), then these connections can be omitted. If the controller is in a metal enclosure, then the enclosure also needs to be grounded. I would leave the alarm disconnected, for reasons stated previously. The alarm can be wired to a buzzer (shown), light, or combo lighted buzzer. A switch in series with the alarm indicator can also be convenient to enable/disable the indicator.

Any questions, just ask.

View attachment 352608

Brew on

Thanks for the diagram.. Yours shows the PID connections and what they are, and that will help me greatly in planning until I order mine and have it in my hands...



On your fuses, are you using actual fuses or resettable breakers (ie push button breakers)?

 

[doug293cz]

240v is not what is used for calculation.. The acceptable voltage range is 220v -240v... (110v-120v for 115v)..

So calculations are done using the 'ideal' target voltage of 230v.. That is what the generating plant seeks to deliver to your premises... Load on the system (or lack thereof), voltage loss due to long wire runs, etc. can affect the system voltage, both at delivery point, or at point of use...

That's why the code requires calculating voltage loss into your on site wiring... In most counties in Ca, they actually make you show it as part of your green sheet when installing a new service or upgrading an old one..


I rounded off, as there's not really much point in carrying it out 4 decimal places... Having installed 'hundreds' of residential services, I'm very familiar with all of this... and it's a PITA in general..

The question is at what voltage does the element actually deliver it's rated power? At any lower voltage, it will deliver lower power, and draw less current. If the element can deliver rated power at less than the maximum possible line voltage, then power at max possible voltage needs to be determined in order to calculate max possible current draw. A possible complicating factor would be if the element had a negative temperature coefficient of resistance. To my understanding, the elements we use have small positive temp coefficients, so we don't have to worry.

Brew on

 

[doug293cz]

Thanks for the diagram.. Yours shows the PID connections and what they are, and that will help me greatly in planning until I order mine and have it in my hands...



On your fuses, are you using actual fuses or resettable breakers (ie push button breakers)?

Either could be used. I don't think there is any benefit to using a breaker for the PID fuse. It might be advantageous to use a breaker for the pump outlet, as it is more likely that the pump could overload without an actual permanent fault condition.

Brew on

 

[caseyw]

The alarm on the MyPin TD4-SNR is an NO contact, so no-go with your idea.

In any case the alarm function in a mashing/boiling application is kind of worthless. You don't want to set the trip point below boiling (for mash mode), or you will have to reset the trip temp every time you switch between mash and boil mode. And, when would it ever trip if the trip temp was set above boiling?

That said, I do show how to wire an alarm in the schematic I'm about to post. But, I wouldn't bother with it.

Brew on

Popping in for one last note, his idea absolutely would work, it doesn't matter if the contacts on the controller are NO. He just needs to use a pilot relay with the coil voltage for the contactor going through the NC contacts of his pilot relay. I drew a mock up a few posts back and attached as a PDF.

 

[doug293cz]

Popping in for one last note, his idea absolutely would work, it doesn't matter if the contacts on the controller are NO. He just needs to use a pilot relay with the coil voltage for the contactor going through the NC contacts of his pilot relay. I drew a mock up a few posts back and attached as a PDF.

You can always add additional components to accomplish just about any functionality. My point was that the PID doesn't provide any NC contacts natively.

Brew on

 

[passedpawn]

The question is at what voltage does the element actually deliver it's rated power? At any lower voltage, it will deliver lower power, and draw less current. If the element can deliver rated power at less than the maximum possible line voltage, then power at max possible voltage needs to be determined in order to calculate max possible current draw. A possible complicating factor would be if the element had a negative temperature coefficient of resistance. To my understanding, the elements we use have small positive temp coefficients, so we don't have to worry.

Brew on

I did measure the current (using a clamp-on ammeter) and voltage across the element once. I'll try to track down that info. From memory, seemed like 235VAC, resulting in lower current. I figured I was getting line losses (I*R) from the line from the breaker box, in the connectors, and through my SSR's. I was pretty happy that I was still getting most of the power at the element though.

Talk about temp coefficients, measure the resistance of an incandescent light bulb and do some math. There's a HUGE temp coefficient there.

 

[doug293cz]

I did measure the current (using a clamp-on ammeter) and voltage across the element once. I'll try to track down that info. From memory, seemed like 235VAC, resulting in lower current. I figured I was getting line losses (I*R) from the line from the breaker box, in the connectors, and through my SSR's. I was pretty happy that I was still getting most of the power at the element though.

Talk about temp coefficients, measure the resistance of an incandescent light bulb and do some math. There's a HUGE temp coefficient there.

In an incandescent bulb, you're talking about ~2000˚ - 3000˚F temperature differential. That's way outside of the range we "should" see in brewing. The temp coefficient is ΔR/ΔT.

Brew on

 

[passedpawn]

In an incandescent bulb, you're talking about ~2000˚ - 3000˚F temperature differential. That's way outside of the range we "should" see in brewing. The temp coefficient is ΔR/ΔT.

Brew on

Right. With incandescent, it's a 10x change in resistance. Pretty impressive. Brewing element shouldn't exceed 212F. Shouldn't Depends on how you clean your element.

 

[doug293cz]

Right. With incandescent, it's a 10x change in resistance. Pretty impressive. Brewing element shouldn't exceed 212F. Shouldn't

Some Google searches confirmed that W (light bulb filament) has a positive TCR. So, I assume you mean that if you measure the resistance at room temp, you will predict much higher current at operating temperature than you actually observe.

The pic of the glowing red element is still less than 1500˚F. You want white light you need to be a lot hotter.
Brew on