PID + SSR = flickering lights?

[OhioBrewingTechnologies]

I feel very strange asking something like this on here but I'm really out of ideas. I have two customers of our HC-3800 (basically PID+SSR+goodies) who don't like how it makes the lights flicker in their house. I don't even know where to begin with it, I've never been somewhere that this was noticeable.

Does anyone who uses PID + SSR notice flickering lights or what do you do about it? I assume during the boil the period is a second or so? At least one guy has the lights and brewery off the same subpanel, so that could be part of it. I just hate telling people "tough."

Thanks.
Dan

 

[mmb]

Actually flickering on and off or just "brown out" type dimming? I've had circuits "dim" and swapping out an old breaker fixed the issue.

 

[JVD_X]

Mine do, but that is because I am drawing so much current from that particular circuit.

 

[OhioBrewingTechnologies]

Oh, I'm pretty sure we're talking about dimming. If it was turning stuff off that's a 100 times worse problem but would probably reset the device anyway. One guy explained it as "pulsating lights", the other was less clear.

 

[Hinermad]

If the lights dim when a heating element goes on it's likely a house wiring issue. Many older homes weren't wired for the kinds of loads we use these days, or just plain aren't wired to balance the load. (I live in a mobile home, and I wish I could shake the guy who put the kitchen outlets on the lighting circuit.) If it's not caused by a faulty connection or component like the breaker that mmb mentioned, putting the brewery on its own circuit might help. But that, and any other solution, is really something an experienced electrician should do.

If the flicker is more of a rapid fluttering like a candle in a draft, that can be caused by a PWM controller that switches at a frequency that isn't related to the line frequency. How rapidly does your controller switch the SSRs? And does it do zero-crossing switching? (Sorry, I'm not familiar with your stuff, but I've been dealing with electricity for a while.)

Dave

 

[OhioBrewingTechnologies]

If the lights dim when a heating element goes on it's likely a house wiring issue. Many older homes weren't wired for the kinds of loads we use these days, or just plain aren't wired to balance the load. (I live in a mobile home, and I wish I could shake the guy who put the kitchen outlets on the lighting circuit.) If it's not caused by a faulty connection or component like the breaker that mmb mentioned, putting the brewery on its own circuit might help. But that, and any other solution, is really something an experienced electrician should do.

If the flicker is more of a rapid fluttering like a candle in a draft, that can be caused by a PWM controller that switches at a frequency that isn't related to the line frequency. How rapidly does your controller switch the SSRs? And does it do zero-crossing switching? (Sorry, I'm not familiar with your stuff, but I've been dealing with electricity for a while.)

Dave

It's zero-cross (Can't please FCC without it) and only turns on or off with integer cycles. So at 60% power it's 30 on, 20 off, period .833 seconds. It's has to just be the line resistance. There's probably no other standard appliance that operates quite this way so we appear to be the bad guys.

 

[Sawdustguy]

If I were a betting man I would say they are drawing a lot of current which is causing a voltage drop either because of a very long run of wire or a bad connection somewhere. The PID turns the element on and off to normalize the temperature to it's set point. I bet that on-off or duty cycle setting on the PID corresponds to the frequency of the dimming lights. This is a potentially dangerous situation because if there is a voltage drop somewhere, power is being dissapating in the form of heat. This is a possible fire in the making.

 

[OhioBrewingTechnologies]

If I were a betting man I would say they are drawing a lot of current which is causing a voltage drop either because of a very long run of wire or a bad connection somewhere. The PID turns the element on and off to normalize the temperature to it's set point. I bet that on-off or duty cycle setting on the PID corresponds to the frequency of the dimming lights. This is a potentially dangerous situation because if there is a voltage drop somewhere, power is being dissapating in the form of heat. This is a possible fire in the making.

Well, I doubt there a hazardous situation going on there, but I'm glad you said this. My response, which should have been my response from the beginning, will be to consult an electrician to make sure there's nothing dangerous with the wiring. Then we add a note in the manual mentioning the same. Done and done, problem solved.

Thank you!

 

[Sawdustguy]

Well, I doubt there a hazardous situation going on there

I pray to God you are right! Having a fire is devestating.

 

[CodeRage]

OBT,
You really should talk to a lawyer about putting some kind of literature in there that the circuit supporting the load is adequate and the responsibility of ensuring that is of the customer's.

My RIMS is on a 120v circuit and the lights to dim when the element turns on and that is with a 10A draw. It is on a lighting circuit as well so it is probably on the upper end of the limit. It is an older home and no telling what code would permit at that time.

I certainly wouldn't tell them to not worry about it. Perhaps they should try a different circuit, or if it really concern's them they should have an electrician investigate it.

Edit:
I had designed a PLC for autos to control lighting, power, solenoids, etc etc. I had one guy try to pump 7 amps through a 22 gauge amp signal wire, cause thats what he had on hand. All of the control circuits had 10 amp fuse protection but since the load was less than the fuse it never blew. For all intents and purposes he had a heating element like knife wire cutting and burning through all kinds of crap on his car. So what does he do? He grabs it with his bare hands to break it loose. I have never been so scared to loose everything I own because some one didn't know what they were doing. Once he notified me of what happened, I refunded his money that instant and asked him to send the device back, I had called a mailbox place local to hiim and made arrangements for him to drop it off. I wanted to sweep this thing under the rug ASAP. Once I got it and saw the wire he used the problem was obvious.

 

[Hinermad]

It's zero-cross (Can't please FCC without it) and only turns on or off with integer cycles. So at 60% power it's 30 on, 20 off, period .833 seconds.

That's 1.2 Hz - well within the range of human perception. That would fit the "pulsating lights" description very well.

(If you want to read more than you ever cared to know about flicker, get a copy of standard EN61000-3-3. It doesn't talk about how to correct it, but it has some good information about human perception of voltage variations. The standard isn't cheap though.)

It's has to just be the line resistance.

I agree, it's a resistace problem either in the wire or the connections.

There's probably no other standard appliance that operates quite this way so we appear to be the bad guys.

The new guy always gets blamed for the problems he uncovers, even if they're not his fault. But you're right, most appliances cycle on and off with a period of seconds to minutes. People get used to the lights dimming when the refrigerator comes on.

Dave

 

[Brewmoor]

When wiring a home in our county. (not sure if it is national code or not.) In the kitchen you have to have x amount of small appliance circuits. There was also a rule that if a pump/motor was 10amps or more it requires a dedicated circuit. Like a garbage disposal.

So I would assume the person having this problem has a circuit overload problem where they are brewing. If lights are dimming chances are there electrical sockets are on the same circuits as the lighting.(small house maybe?)

When people start getting into electric brewing they need to realize they are building a high powered appliance. It should have its own circuit.

Tell the person to count the light bulbs dimming. Add the wattage of all the bulbs and the power of brewing system and see how many amps they are drawing. I bet it is over 15amps or twenty if they are lucky and have 20amp circuits where they are brewing.

 

[cruelkix]

This happens with my PID / SSR set up using a 5500Watt element. Just noticed it today. Hardly a big concern but it is definitely happening on the same frequency of my PID loop. 70% of 1 second on, 30% off. Or what ever it is. My loop is self learning so its constantly changing percentages until it finds the sweet spot. Regardless, its barely noticeable. The light kinda flickers, it doesn't really dim or anything. If anything it dims a very very very small amount. Don't know what will happen when I have the other 3800 watt element on the same circuit. Only time will tell.

GL, HTH,
Craig

 

[Hermit]

OBT,
You really should talk to a lawyer about putting some kind of literature in there that the circuit supporting the load is adequate and the responsibility of ensuring that is of the customer's.

My RIMS is on a 120v circuit and the lights to dim when the element turns on and that is with a 10A draw. It is on a lighting circuit as well so it is probably on the upper end of the limit. It is an older home and no telling what code would permit at that time.

I certainly wouldn't tell them to not worry about it. Perhaps they should try a different circuit, or if it really concern's them they should have an electrician investigate it.

Edit:
I had designed a PLC for autos to control lighting, power, solenoids, etc etc. I had one guy try to pump 7 amps through a 22 gauge amp signal wire, cause thats what he had on hand. All of the control circuits had 10 amp fuse protection but since the load was less than the fuse it never blew. For all intents and purposes he had a heating element like knife wire cutting and burning through all kinds of crap on his car. So what does he do? He grabs it with his bare hands to break it loose. I have never been so scared to loose everything I own because some one didn't know what they were doing. Once he notified me of what happened, I refunded his money that instant and asked him to send the device back, I had called a mailbox place local to hiim and made arrangements for him to drop it off. I wanted to sweep this thing under the rug ASAP. Once I got it and saw the wire he used the problem was obvious.

Electricity isn't hard if you know what you are doing. I had a microwave call and the problem turned out to be he wired his outlet with lamp cord. As a rule of thumb we told folks never to plug an appliance into a cord that was smaller than the one on the appliance and was only as long as needed. And never the long orange ones....

On topic, the first thing I thought was house wiring.

 

[CodeRage]

Electricity isn't hard if you know what you are doing.

I whole heartedly agree. The problem is you cant guarantee the person using the product knows what they are doing. My point was take these issues seriously and don't be flippant about it. Some one's house burns down from an electrical fire and they choose to come after you, because your device made the lights dim. Doesn't matter if they are right or not, litigation is expensive.

OBT, you're LLC'ed right? (I just pulled up your website and it says so on the bottom. I believe that the LLC must be incorporated into your logo as well. At least thats what I was advised to do.)

 

[BrewBeemer]

A PWM in the 400Hz to 1KHz range will be faster switching that the incandescent lights and eyes can not detect. By this first having your wiring and that circuit used for brewing off any lighting circuit and on a dedicated breaker for brewing plus up to handling the amperage load and has been properly installed.

By using a PWM your operating in a manual duty cycle control vs the PID's fixed internal frequency. These higher Hz PWM's have 0-100% duty cycle and can trigger your SSR's or SSRD's as they can switch at a very high frequencies, in the mS range I recall.

There are PWM units that have two pots, one for the pulse width the other for variable frequency adjustment.
In kit forum you solder the components in the $28 range.

For many years in my area lighting and plugs had to be on seperate breakers not mixed together this by code. Over the years may "Popular Mechanics do it yourself home owners" have butchered up their houses taping off any close wiring adding more plugs and lights in older houses this included by those almost off street hired so called electricians.

Many years ago it was a normal practice to mix lights and plugs on the same breaker or circuit. Even aluminum wiring that proved to be a hazard and stopped.

Extension cords are the death of any high current device like high HP compressors well pumps or brewing rigs as an example. As distance increases wire gauge must be increased even higher than the breaker rating due to voltage drop by distance. By this even a couple gauges or more in size increase.

I must feed my Tig welder on 2/4 conductor SOOW cord minimum, any smaller gauge it will electronically lay down with lost heat and welder control at higher amp welding on thick aluminum. I'm pulling 131 amps, 101 amps with the power factor caps added, this on a 150' extension cord to be mobile (1,100 pound welder with bottle on cart) anywhere on my property. Voltage drop on a resistive load like a heating element will greatly reduce your BTU output. Eample your 240 element powered by a 120 volt circuit nets only 1/4 of the BTU heating. Take a long 240 volt circuit cord to your backyard brew rig under load you could be reading only 195 volts feeding the elements.

I have read replies with a wide time difference heating the same volume in gallons with the same wattage elements, makes me think what voltage they have at the element under load?

 

[BrewBeemer]

That's 1.2 Hz - well within the range of human perception. That would fit the "pulsating lights" description very well.
Dave

With that low of 1.2Hz switching just change from bier to drugs and trip out looking at a your lights. No just a added goofy reply. This can set off people that have a unstable mental condition as they can have an attack or flip out.

 

[OhioBrewingTechnologies]

OBT,
You really should talk to a lawyer about putting some kind of literature in there that the circuit supporting the load is adequate and the responsibility of ensuring that is of the customer's.

My RIMS is on a 120v circuit and the lights to dim when the element turns on and that is with a 10A draw. It is on a lighting circuit as well so it is probably on the upper end of the limit. It is an older home and no telling what code would permit at that time.

I certainly wouldn't tell them to not worry about it. Perhaps they should try a different circuit, or if it really concern's them they should have an electrician investigate it.

Our position is that you need to plug our product into a "grounded outlet installed by a licensed electrician" and further that we don't provide advice on how to wire your house.

Although I have probably done so on here occasionally. I do have a lawyer and I'll ask him about that. Sure would take a lot of fun out of things if I'm liable for posts.

 

[Hinermad]

A PWM in the 400Hz to 1KHz range will be faster switching that the incandescent lights and eyes can not detect. By this first having your wiring and that circuit used for brewing off any lighting circuit and on a dedicated breaker for brewing plus up to handling the amperage load and has been properly installed.

By using a PWM your operating in a manual duty cycle control vs the PID's fixed internal frequency. These higher Hz PWM's have 0-100% duty cycle and can trigger your SSR's or SSRD's as they can switch at a very high frequencies, in the mS range I recall.

A higher frequency would certainly reduce the visible flicker, but if you go too quickly you start switching in the middle of a power cycle and that causes radio noise, which the FCC gets very annoyed at. (The Feds are more forgiving of noise in an industrial environment where PWM controllers are more commonly used, but for a product that may be used in the home they're quite strict.)

Besides, if OBT has had only two complaints it's probably not worth making a design change. Changing a commercial product (especially one that requires FCC and UL testing) is expensive.

Dave