MEP-002a LED Light Flicker

[n5yzv]

I've been striving to setup my gen to connect to the house to provide backup power. Thus far, it is connected (I replaced the outer service panel) with a interlock on the panel. I took this time to also install a whole house surge suppressor. Anyway, I connected the gen 240v (each leg measuring 121.5v and 60 Hz). Hz and Voltage stable. I turned off all 240v breakers, one going to my subpanel were lights, outlets, etc are located. With the gen warmed up, I kicked on the Gen breaker, then turned on the sub panel breaker. All was great. I played around with the sub panel + hot water heater (75% load - 22A + 22A) and the subpanel + AC (both air handler and compressor) (55% load). So, yes, I was dam happy it handled the AC. (I live in South Texas)

Anyway, to the question: I noticed that the 120v LED lights (by Cree) have a very slight flicker. Thoughts??

Fyi, I've recently replaced both voltage regulators with after market. voltage and hz stable.

 

[Suprman]

The best way to see whats going on is use an oscilloscope to look at the waveform.

 

[n5yzv]

Yeah, I'm picking up an oscilloscope soon. I grow tired of saying "...if I had an oscilloscope..." The flicker is very minimal, but still present. Thanks!

 

[Isaac-1]

What sort of aftermarket voltage regulator did you use?

 

[Demoh]

I guess Ill have to do the same with the o-scope. Most of my house is Cree led bulbs and when I had the 802 connected I had the same problem. It wasnt so much the cree but I do have a cheaper brand led rope light where it was noticeable. The flicker is the same with a brushed 3600 rpm and my 802a.

with the o-scope what is the best practice, is it to step it down with a transformer or go straight to the line? Ive used my rigol to check out my spindle motor encoder so I have the basics but I havent really dont anything high voltage with it. Ill check the specs for sure but am curious on what everybody else does. Not really looking to blow a scope up.

 

[Triple Jim]

My scope's maximum voltage rating is plenty high for measuring line voltage.

 

[Suprman]

Most scopes are good for high voltage. The input bnc connector should me marked with a max voltage input. Scope is like a multimeter with a visual display. Just takes readings.

 

[kloppk]

Also check the probes to see if they are 1X, 10X or something else.
A 10X probe only passes 10% of the voltage to the scopes input.

Some scopes automatically detect which X factor the probes are and auto adjust the scaling accordingly.
Other scopes don't automatically detect the probe type and can throw the voltage levels displayed off by the X factor.

 

[DieselAddict]

Is the flicker the same regardless of the load on the generator?

When you have the scope out look at the VR output too.

 

[Chainbreaker]

So your saying they are all rock solid on grid power?

Just a FYI, I've got several CREE 120 V bulbs installed inside my house and I am having flickering on a few even on solid utility voltage as well as outright failures only after a year. They usually fail by showing only a faint pulsing glow of led's in bulbs. Not having any problems with other mfg's such as Sylvania. I'm loosing faith in CREE's bulb products. I'm soon going to be shipping a box full of Cree bulbs back to Cree to collect on their 10 yr warranty. However, I'm not having any issues with the 9 Cree bulbs I have installed in outdoor lighting fixtures. Perhaps Cree's circuitry is somehow more intolerant of warmer temperature indoors or voltage/Hz fluctuations over time, vs that of other LED mfg's? They do say not to mount them in enclosed fixtures (not open to airflow) which none of mine are.

 

[n5yzv]

The VR's I used were from http://www.lakeserv.net/mep/
Both are very nice replacements and seem to be made very well.

I'm new to the O-scope world, but I know it can reveal many answers. Regarding Cree, yeah, I have a few light switches that have dimmers in them. I see some pulsing with them. This may be more of a Cree issue than a Gen issue. Maybe I'll pick up a different brand and install on my next run test.

Interesting enough:
Subpanel uses very little power. Maybe 1500 watts on normal basis.
Subpanel + Hot Water Heater = 75% load. Handled it like a champ.
Subpanel + AC unit (I think I have a 5 ton, 15 years old, new start cap) = 50% load. << Being in South Texas I was very happy to see this.
(fyi, I turned on the air handler first and forced the fan to "on". This way I would have less motor spin up at one time)(maybe it helped, maybe not)

A side note, I had an electrician tell me that my little diesel gen would only run one 15A circuit and that I was a fool for trying to use it. Heh. Yeah, some people.

 

[Kenny0]

The VR's I used were from http://www.lakeserv.net/mep/
Both are very nice replacements and seem to be made very well.

I'm new to the O-scope world, but I know it can reveal many answers. Regarding Cree, yeah, I have a few light switches that have dimmers in them. I see some pulsing with them. This may be more of a Cree issue than a Gen issue. Maybe I'll pick up a different brand and install on my next run test.


Not all LED lights are dimmable, usually says on the box when you purchase the light

 

[n5yzv]

Yeah, I noticed the flicker on a traditional switch circuit. But, it is an older style CREE bulb. I'll pay more attention to model when I fire it up next.

 

[Isaac-1]

This may just be due to the inherent nature of small generators having a less than perfect sine wave output. Utility generators generate power at thousands of volts for distribution then use transformers to lower the voltage along the way to our homes, ending up at 120/240VAC for residential customers, due to this process if nothing interferes the end result is a near perfect sine wave, however small generators (up to a Megawatt or so) generate at output voltage, causing distortion caused by the spinning magnetic field windings to be much more apparent distorting the waveform from a perfect sinewave. Over the years generator manufacturers have attempted to minimize this effect with use of techniques like skewed rotor windings, etc.