Recently did a kitchen remodel. Ran a new 20amp dedicated circuit for the microwave. Client purchased a Panasonic microwave with inverter technology. Whenever you run the microwave, the overhead fluorescent lights flicker aggresively, like in the horror flick “Gothika”. Called Panasonic but they do not provide technical support. They referred me to one of their service centers, and they had no idea what would cause this to happen. The owner’s manual mentions that the microwave can cause interference with television reception, and the only way to resolve this is to move either the television or the microwave until the problem goes away.
Anyone else run into this problem? If so any ideas how to resolve the issue, other than moving the microwave around?
Replies
Bump!
Inverter technology?
As in ac to dc power?
Maybe Bill Hartman can explain this one.
Dave
I wonder if the florescents have solid state ballasts? Maybe the microwave has some properties, either as noise on the line or leakage that is affecting the ballasts. I'd try swapping the microwave out, maybe for a different brand.
Well a little bit.
Typical microwaves have a big chunk of iron in them for a transformer. And when you go to less than 100% of power then it works by duty cycling the magnatron on and off. Maybe 10 seconds on and 10 seconds off at 50%. I can hear my old Pansaonic doing this. And you only have a few power settings.
"Inverter technology" replaces the power system with a switching power supply. Those are now very commonn. Computers have used them for years. That is what is in electronic ballast and "electronic transformers" used for low voltage lighting. It is also used in this like monitors have are rated 100-250 volts without a switch or rewiring.
They way that they work is that the 120 volt is directly rectified to DC and go to a capacitor. But the capacitor is fairly small and the voltage has lots of ripple in it.
Then it goes to an electronic switcher and chops the voltage on and off at maybe 5,000 to 100,000 Hertz.
Then it goes to a transformer. Most often a torrid transformer. Because of the high frequency the transformer is much smaller and cheaper than one that works off of line frequency. The high frequency AC is them recitifed back to DC. For some that require precise voltage control there is feed back to the from the rectified output back to thw switch that can change the duty cycle to maintain the exact output although the input (ripple on the recitifed 60 hz) changes.
Also they are easy to generate multiple voltages, such as used in a computer.
Now it has been 40 years since I have seen a magnatron so I don't remember how they work. But I suspect that they have a filament and separate high voltage. Anyway with the inverter then can either change the high voltage and/or duty cycle it, but instead of maybe 10 seconds and 10 seconds off it might be 10 millseconds on and 10 ms off time for 50% power.
I think that Panasonic has the patents on this, but a couple of other MW companies use it and have slightly different names for it.
But they often have power steps from 10 to 100% in 10$ steps. And they are much lighter in weight.
As to the problem.
I doubt that this is the problem, but if it was it would be serious. I would have the microwaved checked and make sure that it is not directly radiating RF and that affecting the floursecnet. A local applicance shop should be able to test it.
What I an guessing is that there is enough energy being "radiated" from the switching power supply (note that the caution about it might affect radio's and TV's) and that the flourscent has a electronic ballast and that there is just enough noise that it is getting "confused".
One thing is that we don't have any idea of how much noise the MW is putting out or how sensity the ballast is (or even if it is a switching ballast).
And we don't know if amount of noise that the MW is putting out is normal or if there is a defect in that unit.
Now as the fix here are a couple of possibilites.
First (after checking that the MW is not radiating RF) is to check the breaker pannel and make sure that all connections are clean and tight. You might re-set the breaker for both, specially the light as it has probably been in there a while. And the neutrals and ground. And if this is a sub-panel check the connects to the main at both ends.
If this does not fix the problem then try swapping the one or the other at the pannel so that if they where on the same hot leg they are now on a different one or if they where on different legs they are now on the same leg.
You can also make sure that all of the connections in the flourscent are good, specaily the grounds. And not only the connections to the power, but fromt he ballast to the light. And that that ballast is firming screweed in place as that is it's ground connection in many cases.
This next level of fixes are harder (or costlier).
Try swaping MW's. See if the appliance source will work with you and maybe try another unit of the same model or a differnt model with similar features. Maybe you can take a display model for a couple of hours to just check it out.
Change the ballast in the light. See if you can get one with a different brand, not that it may be bettter, but just have some different characteristics.
You might check with the ballast manufacture to see if this is a known problem.
You might also try to contact real Pansasonic technical support/engineering. Not "customer service". In fact I am sure that Pansonic would like to know about this.
But I am not sure to tell you how to contact them.
But interestingly about 8-10 years ago I was looking for a local distributor for a specific Panasonic CFL. I found all kinds of contacts on the web and it was real confusing as they where merging and unmerging departments and they kept transfering me from office to office and some people had outdated list of rep's etc. etc. I ended up talking from every one from regional VP's to wharehouse watchment, but in the end I found the name of a local source that could order the part for me.
Looking this time I found a couple of options.
http://www.panasonic.com/fcc/#
This talks about their FCC complain and has a am email contact that might help.
Go through this page and you will end up with several contact options, don't know if they will be help or not.
But if not, ask for a supervisor and tell them that you need to talk to someone in engineering with technical problem.
If you can't get anywhere that way start at the top.
http://finance.yahoo.com/q/pr?s=MC
Ask for the OFFIC of home appliance VP (unji Esaka,
Pres, #### Refrigeration Company; VP, #### Home Appliances Company).
Tell then that you have a problem with a MW and that you need to speak to some one that does engineering support on the MW.
"flicker agressively" as in at about 60 HZ?
If that is the case, Panasonic is being really cheesy and has a straight full wave rectifier in front of their inverter (probably a pulse width modulated full bridge supply).
What this does is pull a big spike out of the middle of the 60 Hz waveform, and can dim lights.
Europe has 5 year old limits on this (harmonic generation requirements on consumer electronics) , but the US still allows consumer electronics without PFC (power factor correction) circuits.
Panosonic is notorious for poor support. Have an inducton cooktop, literally had to take it apart and reverse engineer the controls to fix it after their wimpy mylar circuit board melted thru.
gentlemen,
I would like to thank you for your interest and responses.
Along what Junkhound said, microwaves are notorious for generating harmonics. Basically the unit only draws current when voltage is at it's peak. This causes flat topping (meaning the peak voltage drops and the voltage is no longer a sinusoid) which could cause your flickering. I'll check my sources at work too for you.
You may have to put the microwave on its own circuit. I would also complain to Panasonic about this.
After you check for radiation leaks, try turning the MW unit... it's possible the lamp ballast and the MW power supply are inductively coupled. Rotating or moving one of them will reduce the coupling.
Lets us know what you try and what works.
On the "strange problem" type of questions feedback is rare, but greatly adds to the collection knowledge base of Breaktime.
You could try making sure the MW and lights aren't on the same phase in your loadcenter, I've seen this when they share a neutral,also. An electrical contractor with a fluke scope meter can look at the harmonics at the cord connection but the dv/dt filters required to correct this aren't a cost effective solution...good luck
Double check all, or at least all you can get to, neutral and ground connections on both circuits. I would also check the hots just to be anal about it.
You might also try moving the light to the opposite phase within the breaker panel. Beware of any shared neutral situations.
Scion,
Stop using the Microwave immediatley until you have it checked for leaks. It may not be the problem, but a bad enough leak WILL cause flourescent lamps to flicker, even when they are not turned on. It is not worth the risk.
Bill Koustenis
Advanced Automotive Machine
Waldorf Md
I'm thinking there is a leak in the MW. The stray microwaves are exciting the gas in the flourescent tubes.
You get out of life what you put into it......minus taxes.
Marv