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hobbes
Joined: 08 Sep 2017 Posts: 26
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Link Posted: Wed Oct 25, 2017 4:16 pm Post subject: Contactor emf illuminating bulbs |
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I've got a strange issue where the lights on the panel will flash when any contactor energizes or releases. (pump lights, alarm light, power light, everything except the element lights).
I'm testing out my 50amp panel with a single 120/neutral/ground on the workbench to make sure the interlock, PIDs, DC supplies, etc are all wired correctly (they appear to be fine). However, when i first turn on the unit and the main contactor kicks on there is a brief flash from any lights on the panel. It's so brief i didn't notice until testing the element switch a few times.
When selecting the element i see the same flash from bulbs when the contactor fires or disengages.
I've started disconnecting wiring to where i'm down to just kicking the contactor on with a jumper and only having a neutral connected to one light and it flashes. Since only neutral and no hot is connected i have to think there is some kind of induction or noise being generated by the contactors when they kick on. This is with the lid open so I don't think it could be induction/noise from being close to the coil in the contactor... rather it has to be something generated from the contactor closing. It is connected by the neutral bus, the hot is broken by a switch.
It makes sense to me that the element lights don't flash, since they're wired straight to the hot legs on the contactor and have no neutral. If i disconnect the neutral wires from the lights they don't flash, it appears to be something coming back on the neutral bus. Although, how it's able to flash a light with neutral and no ground is beyond me... I've only seen that behavior with telsa coils. The lights don't appear to have any way to ground due to plastic bodies so even a hot 110v coming down the neutral i would suspect has nowhere to exit.
Also, hooking a volt meter up as a/c across the neutral and grnd, neutral/hot, hot/grnd produces no flash of current on the fluke when the lights flash. It may be so quick that it doesn't register.
I've started going through the panel to make sure i don't have something grounded that should be on neutral, but i'm pretty positive I've got it wired correctly. The last test I did was just hot and neutral to the main contactor and neutral to one light. The light flashes when i hit the contactor with power, rest of the panel disconnected... nothing on the contactor except a neutral going to a light which has nothing else connected to it.
Just some more info on the test setup. This is testing on work bench with one hot, neutral and ground connected in via the California connector at the bottom.
Looking for any advice on what to check next. I've never seen something like this except with a telsa coil which can light bulbs with high freq current through air by using you as the ground.
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kal Forum Administrator
Joined: 12 Dec 2010 Posts: 11123 Location: Ottawa, Canada
Drinking: Pub Ale, Electric Creamsicle, Mild, Pliny the Younger, Belgian Dark Strong, Weizen, Russian Imperial Stout, Black Butte Porter
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Link Posted: Wed Oct 25, 2017 4:35 pm Post subject: |
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Strange. I've never seen or heard of this happening. Lighting light bulbs with Tesla coils however is possible of course - example: https://www.youtube.com/watch?v=DGk3O-zg2E8
Are you sure it's from the contactors? Normally if it's from a coil you'd need to have the light bulb pretty close (like in the video above), and moving it away would have it turn off. Does it still happen with the door wide open? (light bulbs far away from the contactors). If yes, then I'd say it's pretty safe to assume it's a wiring issue somewhere and not magnetic fields.
Kal
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hobbes
Joined: 08 Sep 2017 Posts: 26
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Link Posted: Wed Oct 25, 2017 5:57 pm Post subject: |
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kal wrote: | Strange. I've never seen or heard of this happening. Lighting light bulbs with Tesla coils however is possible of course - example: https://www.youtube.com/watch?v=DGk3O-zg2E8
Are you sure it's from the contactors? Normally if it's from a coil you'd need to have the light bulb pretty close (like in the video above), and moving it away would have it turn off. Does it still happen with the door wide open? (light bulbs far away from the contactors). If yes, then I'd say it's pretty safe to assume it's a wiring issue somewhere and not magnetic fields.
Kal |
It does indeed happen with the door wide open. Im going to remove a contactor and wire it up on the desk with just hot and neutral with a bulb hanging off only neutral to take the box out of the equation.
I can find some related emf articles regarding inductive loads and using a capacator and resisgor to snub the voltage spikes due t9 the coils being energized/denergized but i have no loads attached to this setup yet (no elements plugged in). Hoping its instead an issue with my wiring as that would be the cheapest and easiest fix... but i cant seem to find anything wrong.
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JSB
Joined: 17 Oct 2016 Posts: 125 Location: NE Ohio
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hobbes
Joined: 08 Sep 2017 Posts: 26
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Link Posted: Wed Oct 25, 2017 7:57 pm Post subject: |
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I sure do... as part of the interlock.
Also, I pulled a contactor out and hooked hot/neutral up to it with a bulb hanging off and it's not causing the issue i'm seeing in the panel. Therefore I must have messed something up... I'm going to start undoing components where I can and see if i can narrow it down further. Even with the contactor's coils unwired i'm seeing a small flash when i turn the key... so i'm suspecting the interlock wiring.
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hobbes
Joined: 08 Sep 2017 Posts: 26
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Link Posted: Wed Oct 25, 2017 11:42 pm Post subject: |
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I've ran the hot 120 straight to the safestart coil and unhooked the rest of the board... except the power key and NC loop. I still seem to get a brief flicker. when i turn off the power. If i unhook the NC loop and jumper 2 & 8 the flicker goes away. I must be getting some EMF through the NC contactor loop. I still can't quite explain it, the wiring seem solid.
I also notice this only happens when the relay or contactor is released.
I'm wondering if someone else can power their panel up, perhaps in the dark... and eyeball the LEDs to see if they illuminate at all when the power key is flipped off and back on. When i bypass the NC circuit on the safestart the lights do not flash, i suspect the EMF is causing them to flicker on for a brief second. It's only a slight millisecond of flash.. I'm wondering if i neeed to re-route my NC and/or separate my neutral and hot wire routes instead of having them all zipped tied together.
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kal Forum Administrator
Joined: 12 Dec 2010 Posts: 11123 Location: Ottawa, Canada
Drinking: Pub Ale, Electric Creamsicle, Mild, Pliny the Younger, Belgian Dark Strong, Weizen, Russian Imperial Stout, Black Butte Porter
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hobbes
Joined: 08 Sep 2017 Posts: 26
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Link Posted: Thu Oct 26, 2017 1:21 pm Post subject: |
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Thanks. Can you try selecting elements back/forth and the power off? It appears I get the flicker when its the coil de energizing.
Today Ill grab a video so you can see. Im also going to finish wiring the nema plug so im using 240 out of a proper outlet and not 120 out of a hacked plug at my desk for testing. I'm hoping ive created my own problem with bad testing procedures.
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hobbes
Joined: 08 Sep 2017 Posts: 26
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Link Posted: Thu Oct 26, 2017 8:50 pm Post subject: |
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I was able to reproduce this with one contactor and one light on my desk by toggling the input power via a surge protector/strip. It doesn't seem to happen unless the light has a wire on both terminals and at least the neutral or hot going to the same "bus" as the contactor. My test setup has a stripped power cord with the hot clamped to the contactor coil, ground clamped to the contactor base, and the neutral attached to the other side of the coil. The light has 2ft wire going to the neutral side of the contactor. I tried once without anything on the other side of the lights post (nothing), then after attaching a 2ft cord sitting attached to nothing i observed the same behavior of flashing when the contactor closes (powered off). It doesn't matter if i use the neutral or hot side of the contactor attached to the light.
I'm wondering if my panel is experiencing this because it's a 50amp with contactors rather than relays... maybe there aren't as many people going this route that would have noticed. Or maybe i'm being over dramatic about the flash i'm seeing... i could see how this could easily be disregarded as nothing, but my concern would be if this is EMF/EMI that the PIDs and/or timer may get damaged over time if there are high voltage spikes as the contactors release.
I'll see if i can find somewhere to upload these vids I grabbed with my phone. I took a vid of the panel before hand showing the pump lights flickering, one of the contactor on my desk with nothing but a light hanging with one neutral, then the same setup with a wire hanging off the light's hot showing it flickering with power off.
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hobbes
Joined: 08 Sep 2017 Posts: 26
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Link Posted: Thu Oct 26, 2017 9:15 pm Post subject: |
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Tried creating a tmp instagram account... let me know if this works. Please disregard any blatant safety violations... i know there are probably tons of safety issues with wiring a contactor straight out of a cut power cord, just trying to do my best to eliminate all the variables here and find the source of my issue.
Panel on desk when I was testing, showing pump and power light flickering:
https://www.instagram.com/p/BaudSyjj-yy/?hl=en
Contactor on desk showing flashing light, then removing the pigtail on light and it stops:
https://www.instagram.com/p/BaudM-ijkF0/?hl=en
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kal Forum Administrator
Joined: 12 Dec 2010 Posts: 11123 Location: Ottawa, Canada
Drinking: Pub Ale, Electric Creamsicle, Mild, Pliny the Younger, Belgian Dark Strong, Weizen, Russian Imperial Stout, Black Butte Porter
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Link Posted: Thu Oct 26, 2017 11:14 pm Post subject: |
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hobbes wrote: | Or maybe i'm being over dramatic about the flash i'm seeing... i could see how this could easily be disregarded as nothing, but my concern would be if this is EMF/EMI that the PIDs and/or timer may get damaged over time if there are high voltage spikes as the contactors release. |
No - I would not be concerned with this. It's not going to damage anything.
The flash is so dim and fast that it will not confuse the operator either, especially since it only happens when the operator is switching something.
I think what you're seeing is due to the fact that you have no loads attached to sink the current. Attach heating elements and pumps and you will not notice the subtle flashing.
Kal
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Last edited by kal on Thu Oct 26, 2017 11:24 pm; edited 1 time in total
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kal Forum Administrator
Joined: 12 Dec 2010 Posts: 11123 Location: Ottawa, Canada
Drinking: Pub Ale, Electric Creamsicle, Mild, Pliny the Younger, Belgian Dark Strong, Weizen, Russian Imperial Stout, Black Butte Porter
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Link Posted: Thu Oct 26, 2017 11:24 pm Post subject: |
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Err, wait a sec - I know why... your videos show it well: It's because you don’t have the PIDs, timer, meters, or any of the other 120v sources hooked up to sink the current from the 120V lights. You don’t even have the 120v blue power light connected. That explains why you see it in the 120v lights only and not the 240v element lights. Long story short: All is normal! The energy from the coil has to go somewhere when you disconnect power and currently the lights are the only place... had you just hooked up the blue power light to come on per the instructions then that would have probably done it. (I had assumed you had finished your wiring but nothing seems to be connected yet...)
Kal
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My basement/bar/brewery build 2.0
Last edited by kal on Thu Oct 26, 2017 11:29 pm; edited 1 time in total
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hobbes
Joined: 08 Sep 2017 Posts: 26
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Link Posted: Thu Oct 26, 2017 11:25 pm Post subject: |
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Good to know... i was a little worried that nobody else has seen this. but it's entirely possible nobody noticed or just didn't give it a second thought. I'm going to research a little and see if there isn't something i can place across the coils like a filter or cap to prevent the issue since it bothers me a little. I'll post back if I find something so it can be included on 50amp panels.
I'll also reply to show what we look like once heat sticks and pumps are actually wired up and i'm off a NEMA plug in the garage. Curious to see if the issue still persist.
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hobbes
Joined: 08 Sep 2017 Posts: 26
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Link Posted: Thu Oct 26, 2017 11:30 pm Post subject: |
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Yes, the HLT lights don't flash and i figured it was because they're 240vac wired to the contactors main leads which aren't powered yet. I knew it had to be something with the coil closing and current being stuck/getting out from the coil after the switch is shut but the coil is still energized. I'm just not sure how the voltage is so high it can illuminate a bulb that only has a neutral wire plugged in and the hot wire unplugged.
Hoping i can figure out what combination of resitor/cap or filter could be placed across the coil to safely drain the contactor coil voltage when it's suddenly shut off. Until then, i guess i won't worry too much about it. The hvac systems use contactors and don't seem to suffer much from the emi/emf i'm seeing.
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kal Forum Administrator
Joined: 12 Dec 2010 Posts: 11123 Location: Ottawa, Canada
Drinking: Pub Ale, Electric Creamsicle, Mild, Pliny the Younger, Belgian Dark Strong, Weizen, Russian Imperial Stout, Black Butte Porter
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Link Posted: Thu Oct 26, 2017 11:31 pm Post subject: |
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You could put a resistor across to sink the current but I wouldn’t bother as it’s not an issue. It’s just physics behaving as it’s supposed to.
One you hook up at least one device the flashing will go away.
Kal
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My basement/bar/brewery build 2.0
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hobbes
Joined: 08 Sep 2017 Posts: 26
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hobbes
Joined: 08 Sep 2017 Posts: 26
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Link Posted: Thu Oct 26, 2017 11:54 pm Post subject: |
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Found one more... seems someone found "resistors" across some contactors and posted asking what they were:
http://www.electriciantalk.com/f28/contactor-23610/
Looks like MOV or 'rc snubb' is the proper way to sink that voltage, if it's needed. Someone mentions it's usually not necessary and they're probably right. Still, would be to sink this away from the LEDs and toward grnd.
I'll report back if I can figure out the math on the snubber or the proper MOV and wiring.
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kal Forum Administrator
Joined: 12 Dec 2010 Posts: 11123 Location: Ottawa, Canada
Drinking: Pub Ale, Electric Creamsicle, Mild, Pliny the Younger, Belgian Dark Strong, Weizen, Russian Imperial Stout, Black Butte Porter
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Link Posted: Fri Oct 27, 2017 12:04 am Post subject: |
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hobbes wrote: | I do have the PIDs and timer wired up... but the flashes still happen as i turn the element selector or turn off the board. |
But in your first video none of those things turn on when you power up the panel. The blue power light doesn't even come on, nor do the meters.
Quote: | The PIDs may not be pulling enough current, but at the end of a brew day i'll have the pumps and elements off... be nice to not see a flash when i turn the key off. |
With the power light, PIDs, timer, and meters on, as well the elements and pumps connected, you should not see any flash.
Quote: | I may wait until I've got this setup in the garage with actual pumps and elements before i invest too much time in figuring out a proper filter. |
That would be my suggestion.
Kal
_________________ Our new shop with over 150 new products: shop.TheElectricBrewery.com
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My basement/bar/brewery build 2.0
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kal Forum Administrator
Joined: 12 Dec 2010 Posts: 11123 Location: Ottawa, Canada
Drinking: Pub Ale, Electric Creamsicle, Mild, Pliny the Younger, Belgian Dark Strong, Weizen, Russian Imperial Stout, Black Butte Porter
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Link Posted: Fri Oct 27, 2017 12:08 am Post subject: |
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hobbes wrote: | Looks like MOV or 'rc snubb' is the proper way to sink that voltage, if it's needed. |
A MOV (metal oxide varistor) is a protective device - it's not for sinking voltage: https://en.wikipedia.org/wiki/Varistor
RC (resistive/capacitive) solutions are used sometimes across contactor or relay coils to avoid 'chatter', something that doesn't happen here. Many relays will have them built in.
Kal
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hobbes
Joined: 08 Sep 2017 Posts: 26
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Link Posted: Fri Oct 27, 2017 12:52 am Post subject: |
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kal wrote: | hobbes wrote: | I do have the PIDs and timer wired up... but the flashes still happen as i turn the element selector or turn off the board. |
But in your first video none of those things turn on when you power up the panel. The blue power light doesn't even come on, nor do the meters.
Quote: | The PIDs may not be pulling enough current, but at the end of a brew day i'll have the pumps and elements off... be nice to not see a flash when i turn the key off. |
With the power light, PIDs, timer, and meters on, as well the elements and pumps connected, you should not see any flash.
Quote: | I may wait until I've got this setup in the garage with actual pumps and elements before i invest too much time in figuring out a proper filter. |
That would be my suggestion.
Kal |
Sorry for the confusion there. The video was taken after i had disconnected the PIDs, alarm and pump 'hot' wires while troubleshooting. I had finished the wiring completely and was checking things when i noticed the illumination and began disconnecting items to locate the source/issue.
I did re-attach everything and see the same issue. I'll take a video again if i see the same issue once pumps and everything is wired up in the garage. I'm wondering if having the pumps connected if they'll help squelch that current enough to make the flashes completely go away. I'm still awaiting my HLT with TC ports before i swap everything over from my propane panel to the Electric Brewery one so it may be a week or so before I can report back.
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