Help!!!!

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geoffgelectric

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ventura ca
Hey guys,

I don’t post too often. I’m more of a lurker but I appreciate all the info and knowledge on here big time.

Hopefully you guys can provide some insight to what might be happening on a job I just finished. Im all out of ideas and or reasons.

Just finished a new single family 12k sq ft build here in Los Angeles. 400amp main with 1 - 200amp sub and 2- 100amp subs and 1 - 125a Infratech control panel for 4-6000w 220v Infratech heaters which is tapped off the 200amp sub.

Owner just moved in and I got the call that when they turn the heaters on and set them at any setting other than 100 percent on the analog thermostat control that all the lights in the house flicker. When the control is set to 100 percent there is no flicker. ALSO… the NEIGHBORS LIGHTS flicker as well..

Now the POCO (LADWP) has come out and run their tests and the owner said it came back normal .. (I’m not sure if I fully believe it but I can’t go up the pole and test their transformer)

I oversized my feeders to the 200amp sub and I ran 1awg to the Infratech 125amp control panel which is only 2’ from the 200amp sub anyway. I spoke with Infratech 5 times already and they claim it’s a POCO issue.

Has anyone here experienced anything like this with Infratech or any other large load on a new build?

Any advice or knowledge is greatly appreciated. I’m at my wits end.


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Take voltage readings
Open circuit with no load
Operating voltage and then use min reading when heaters turn on
And amp readings when heaters turn on
Post what you find
FYi, The human eye is very sensitive to light flicker.
What type of load does the neighbor have?
 
tom baker said:
Take voltage readings
Open circuit with no load
Operating voltage and then use min reading when heaters turn on
And amp readings when heaters turn on
Post what you find
FYi, The human eye is very sensitive to light flicker.
What type of load does the neighbor have?
Click to expand...

Voltage 239.2 - no load
Voltage 236.9 with load at 100 percent
Amp - 110amp full load
The flicker is strobe effect style flicker. Very noticeable
Not sure of neighbors load but POCO is testing their drop as well


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LarryFine said:
It sounds like the heaters use PWM to modulate the heat. Full voltage, but switched rapidly.
Click to expand...
Yes. I've seen something similar with large kw electric heaters and the controller chops the sinewave not cleanly. Not sure what type of electronic device they were using to chop the sinewave, but the result was excessive heating of everything I had put in to feed them, the bolt on panel, the breakers, and the circuit, which was oversized. The panel and breakers ran really warm.

Sounds like that Infratech controller for the heaters is a "noise generator". Then the other loads are sensitive to the noise with a result that is visible. It's possible the utility transformer is also sensitive to the noise with a result of excessive heating, just not sensitive with a result that is visible.

You could contact Infratech would be my first guess and tell them they're getting the blame, see what they say. From my point of view i would want to see how they are about factory support. They might be good, or not.

As far as mitigation, idk, but I am thinking you could try a line reactor in front of the Infratech controller, as a guess. It's an adder at this point. It could also be radiating RF, which would be a different problem.
 
What kind of lights are we talking about - incandescent or LED's?

I agree with Larry - probably a PWM control on the heater, causing large current spikes that drop the voltage during part of the cycle. If the lights also have a PWM dimmer (LED's?), then the voltage drop can trick the dimmer PWM into turning on or off at the wrong time - hence flicker.

If the neighbors lights are flickering also, I want to say the POCO transformer is undersized, but that's hard to believe since it's such a large house with a 400A service. And good luck trying to get the Power Company to install a larger transformer.

Some type of filter would probably help. Either on the heater, or on the lights, which is why I ask about the lights.

But I'm not sure if there are any "on the shelf" solutions available.
 
If there are no incandescent lights, I suggest trying an incandescent without a dimmer to see if it flickers. If it also flickers, then you have a bigger problem on your hands than if it doesn't. That would mean that it's not only higher frequency content that's causing the problem.

I agree with _dan that a line reactor in front of the heater controller might help.

It would be helpful if you could put an oscilloscope on it to see what's really happening.
 
I've seen this with much lower power PWM modulated heaters and LED lights.

I have a 'heat gun' with electronic temperature control. When I use it, my LED shop lights flicker. Noticeably if they are on a separate circuit, really annoyingly if they are on the same circuit. And this is something that can plug in to a 15A 120V outlet.

LED lighting drivers seem particularly sensitive to this sort of noise.

Can you share the part number for the control panel? Is it using fancy SCR devices with zero cross switching or something slower, or even mechanical switches?

Do other high power heating loads (such as an electric cooktop or water heater) cause noticeable flicker?

-Jon
 
It is both incandescent and LED that flicker at the house. If it was an undersized POCO trans wouldn’t it be flickering when heaters were at 100 percent? They flicker at 15 percent more than 80.

Thanks again for your time


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synchro said:
If there are no incandescent lights, I suggest trying an incandescent without a dimmer to see if it flickers. If it also flickers, then you have a bigger problem on your hands than if it doesn't. That would mean that it's not only higher frequency content that's causing the problem.

I agree with _dan that a line reactor in front of the heater controller might help.

It would be helpful if you could put an oscilloscope on it to see what's really happening.
Click to expand...
One would think that the mfg could make those heaters work on a cycle of one 6KW load at a time, doing all within a 10? sec sequence. Still using the PWM.

Sounds easy from here.
 
When the heaters are at 100%, they are fully on. You get voltage drop at the transformer and service drop, but it is a _steady_ drop. So the lights end up slightly dimmer, but _steady_, so you don't see any flicker.

The flicker is because the heaters are being rapidly turned on and off, causing the voltage to fluctuate rapidly.

-Jon
 
ptonsparky said:
One would think that the mfg could make those heaters work on a cycle of one 6KW load at a time, doing all within a 10? sec sequence. Still using the PWM.

Sounds easy from here.
Click to expand...

It depends upon how smart (and integrated) the control for the heaters is.

The heaters are cheap and use lots of power. The basic controls are simple 'bi-metallic' clickers such as used for old electric stoves.

They also sell solid state controls. It would certainly be possible to design a solid state control which modulates each heater in a smart fashion, and synchronizes the different loads to minimize external disturbance. You could even play tricks like putting modules in series to reduce modulation during low power operation.

To the OP: how much modulation does the customer really want? Maybe you could eliminate the continuously variable controls, and instead have a switching arrangement to adjust between different power levels. Really fancy with absolutely no flicker would involve a transformer to reduce voltage to the heaters.

-Jon
 
If you want to "prove" it's the heaters, build a bank of standard heaters at 6kw, connect in place of the fancy one, and watch the voltage & lights when you manually switch it on/off. Odds on you'll see spikes & flickers; then it's a call to the manufacturer.

Or put a oscilloscope on the line and watch the traces.
 
steve66 said:
If the neighbors lights are flickering also, I want to say the POCO transformer is undersized, but that's hard to believe since it's such a large house with a 400A service. And good luck trying to get the Power Company to install a larger transformer.
Click to expand...
What if the neighbor was the one to file a complaint with the POCO?
 
geoffgelectric said:
when they turn the heaters on and set them at any setting other than 100 percent on the analog thermostat control that all the lights in the house flicker.
Click to expand...
All I can say is I see this more and more often.
Large transistor or solid state relay controlled loads rapidly switching.
Recently for me it was lighting flicker due to a 36kW on-demand water heater that rapidly switches on/off.


__dan said:
As far as mitigation, idk, but I am thinking you could try a line reactor in front of the Infratech controller, as a guess. It's an adder at this point. It could also be radiating RF, which would be a different problem.
Click to expand...
Thats a good idea.
Could also add a capacitor bank to the lighting panel ?
 
geoffgelectric said:
It is both incandescent and LED that flicker at the house. ... They flicker at 15 percent more than 80.
Click to expand...

Having incandescent bulbs flicker that way sounds like the heater control is using burst firing (bursts of entire 60 Hz cycles) instead of phase angle control (which conducts just a portion of each cycle. The thermal time constant of incandescent bulbs is too long to have a significant response to the harmonic content of phase control with SCR's, because it's all at frequencies above 60 Hz. But burst firing will have a much longer cycle rate where it switches between contiguous cycles that are at full output power, and a time period with zero output power.

Example waveforms of burst and phase angle control are shown in this post:

https://forums.mikeholt.com/threads...-of-scr-power-controller.2572864/post-2817000

A reactor is likely to have little effect with incandescent bulbs when burst firing control is used. But it still might help with LED lights because they respond more to the rate at which the voltage changes vs. the longer term RMS voltage level. A capacitor at the lighting panel like tortuga mentioned might also help with LEDs, but not with incandescents.

If the controller is in fact using burst control, it could be worthwhile to try a phase angle controller. It generates harmonics, but they should be steady harmonics and so the lights might tolerate them better.
 
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