[RE-wrenches] Flickering LED lights on and Outback Dual 7248VFXsystem

[Exeltech]

If only LED lamps on dimmers are flickering, suspect the dimmers, but this isn't yet certain.  This can be assessed by plugging one of the flickering LED bulbs into the same circuit, but use the bulb in a table lamp and plug into an AC outlet to bypass the dimmer.  Does the LED bulb still flicker?  If so, the dimmer can be exhonerated for now.  It also means you have more work to do... 

Another wrench suggested using an oscilloscope to evaluate the AC waveform.  That was THE best recommendation, and  should be your #1 task.  It will immediately help to indicate the culpret.  The waveform should be perfectly sinusoidal.  Dimmers rely on a phase shift circuit to turn on the power to the load.  If the AC waveform is distorted, it can cause the dimmer to activate erratically, and turn on at different points in each cycle of the AC waveform .. leading to flickering.

Pay VERY careful attention to "hot" and "neutral".  You want the 'scope probe tip on the "hot" conductor; and the scope "ground" on neutral.  Make certain the scope is in the "Hi-Z" mode (some 'scopes have a 50 ohm setting in the probe or elsewhere.)  Measure carefully -- and use a "ground-buster" to isolate the 'scope.  (Ground-busters are those three-to-two AC socket adapters originally intended for use where the third-pin "ground" didn't exist, as in older homes.)  Pay careful attention to the cleanliness of the waveform AND the consistency of the amplitude.  Either or both out of spec can cause flickering.

LED bulbs are significant sources of "EMI". "EMI" = electromagnetic inteference .. aka "radio frequency interference" .. and can affect AM radio, FM radio, and other "receiving" devices up to some surprisingly high frequencies.  Remedial options are limited here .. and are a topic for a totally separate discussion.


Dan




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On Tue, 1/7/14, Chris Daum <chris at OasisMontana.com> wrote:

 Subject: Re: [RE-wrenches] Flickering LED lights on and Outback Dual 7248VFXsystem
 To: "'RE-wrenches'" <re-wrenches at lists.re-wrenches.org>
 Date: Tuesday, January 7, 2014, 8:51 AM
 
 
We have a variety of LEDs, cheap, expensive, etcetera -- but no dimmers.  We have shown no sign of flickering in any of them off our Radian inverter.
 
Chris Daum
Oasis Montana Inc.

From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of toddcory at finestplanet.com
Sent: Monday, January 06, 2014 9:10 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Flickering LED lights on and Outback Dual 7248VFXsystem

the only ones i have on a dimmer are in the bathroom and they flicker. being we are grid tied (GVFX-3648) and the grid is up, i suspect this is because of a bad dimmer/lamp combo.

anyone find the RFI from led lamps a problem? i have to shut all mine off when using the 2 meter ham rig.



todd


On Monday, January 6, 2014 7:56pm, "frenergy" <frenergy at psln.com> said:

Another $.02....
I have 2, FX3524's and 35 KWhrs of HUP's behind them....just cleaned and torqued the terminals/cables.  I run 6-7 brands, sizes, styles of  LEDS and some of them of them flicker while, in my case, the convection oven is running.  It quickly pulses (~10-20 times/second) to maintain a temperature.  Fridge is DC. The less expensive off-brand LEDs flicker, the big name brands don't.
Bill