Previous in Forum: Bucket Elevator Sensors in Cement Plant   Next in Forum: Help with designing a Load Cell with DMS
Close
Close
Close
38 comments
Power-User
Engineering Fields - Electrical Engineering - New Member Engineering Fields - Power Engineering - New Member

Join Date: Mar 2012
Location: the sandbox
Posts: 340
Good Answers: 6

Three Window Air Conditioners Catch on Fire

05/23/2015 7:56 AM

3 of our window air conditioners caught on fire. We "believe" the compressor motor went bad, and the start capacitor burst and started the fire. 2 of the 3 "allegedly" has AFCI as required by NEC 440.65. So maybe the AFCI failed? or the AFCI was too slow to stop the fire from starting?

Solutions? I was thinking of a simple thermal cutout I could wire into the input power for the HVAC, and as NEC 440.52A2 requires, I would co-locate it right next to the start capacitor. Any part recommendations for this? Something simple please!

__________________
BSEE but always learning
Register to Reply
Pathfinder Tags: fire window air conditioners
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Guru

Join Date: Sep 2012
Location: Iowa, USA
Posts: 577
Good Answers: 50
#1

Re: Three Window air conditioners catch on fire

05/23/2015 8:47 AM

Three identical failures of compressor failure, which then causes capacitor failure, and then the oil ignites, does not appear that the design was validated by any underwriter/safety compliance organization.

Did someone mess with the design and bypass the motor protection current tripping device? To me the only common mode possibility is the maintenance personnel.

Arc Fault Circuit Interrupt detects arcing, I bet the current flow though a failed capacitor looks like a low resistance behavior current path, and does not trigger the breaker.

__________________
ignator -
Register to Reply
Guru
Popular Science - Cosmology - New Member Technical Fields - Technical Writing - New Member Engineering Fields - Energy Engineering - New Member Engineering Fields - Electrical Engineering - New Member Engineering Fields - Control Engineering - New Member Engineering Fields - Electromechanical Engineering - Old Member, New Association

Join Date: Apr 2008
Location: Lexington, KY
Posts: 1640
Good Answers: 72
#28
In reply to #1

Re: Three Window air conditioners catch on fire

05/27/2015 2:31 PM

The title sent me off down a lonely road.... I thought it was going to be some kind of joke like, "Three guys walk into a bar....

__________________
A great troubleshooting tip...."When you eliminate the impossible, whatever remains, however improbable, must be the truth." Sir Arthur Conan Doyle
Register to Reply Off Topic (Score 5)
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 14331
Good Answers: 161
#29
In reply to #28

Re: Three Window air conditioners catch on fire

05/27/2015 4:33 PM

No...that would three window washers catch on fire.

Three window washers walk into a bar....

__________________
If it ain't broke, don't fix it. Just build a better one.
Register to Reply Off Topic (Score 5)
Power-User
Engineering Fields - Electrical Engineering - New Member Engineering Fields - Power Engineering - New Member

Join Date: Mar 2012
Location: the sandbox
Posts: 340
Good Answers: 6
#2

Re: Three Window air conditioners catch on fire

05/23/2015 9:53 AM

motor cirucit protection (branch circuit breaker) is installed, anything internal to the window unit would be intact before the fires, our maintenance stafff is unlikely to be active or creative enough to take apart window units and bypass what is internal to them

__________________
BSEE but always learning
Register to Reply
Power-User
Engineering Fields - Electrical Engineering - New Member Engineering Fields - Power Engineering - New Member

Join Date: Mar 2012
Location: the sandbox
Posts: 340
Good Answers: 6
#3

Re: Three Window air conditioners catch on fire

05/23/2015 9:56 AM

so what i need is a 1-piece thermal trip device, I cut the input power, wire in this device, power is immediately cut when temperature exceeds 60 degrees C, for example.

__________________
BSEE but always learning
Register to Reply
Guru

Join Date: Feb 2008
Location: Large hole formally occupied by furry woodland creature.
Posts: 3385
Good Answers: 97
#4

Re: Three Window air conditioners catch on fire

05/23/2015 10:33 AM

Sounds like a line voltage problem.

__________________
CRTL-Z
Register to Reply Score 1 for Good Answer
2
Guru

Join Date: Mar 2007
Location: at the beach in Florida
Posts: 31292
Good Answers: 1733
#5

Re: Three Window air conditioners catch on fire

05/23/2015 12:22 PM

This sounds like defective components having catastrophic failure, not likely to be saved by thermal cutout...I would contact the manufacturer and confront them with the evidence and request replacement or fix at their expense...including any damages caused by defective component failure....You need to get to the bottom of the problem before attempting any alteration, which could have unintended consequences...including making you the one to blame...

__________________
Break a sweat everyday doing something you enjoy
Register to Reply Good Answer (Score 2)
Guru
Engineering Fields - Power Engineering - New Member

Join Date: May 2007
Location: NYC metropolitan area.
Posts: 3231
Good Answers: 444
#6

Re: Three Window air conditioners catch on fire

05/23/2015 2:12 PM

C'mon, three suspicious fires in the same time period? Either you have a severe persistent overvoltage (but why didn't more equipment fail), or a pyromaniac on the loose.

__________________
“Tell me and I forget. Teach me and I remember. Involve me and I learn.” Ben Franklin.
Register to Reply
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 14331
Good Answers: 161
#25
In reply to #6

Re: Three Window air conditioners catch on fire

05/26/2015 3:07 PM

Usually it is low line voltage that leads to failures (electrical over heat) of high wattage 120VAC or 220VAC (EU) appliances. Apparently, there is a power gen problem (local grid overload due to high heat) in your sandbox. Check with them, and request voltage records (open records in the U.S.) if they allow that where you live.

You probably had all three of the AC units on separate breakers, and these were probably breakers that were too large for the load to the AC units. I.E.- if the normal voltage supply would operate the full load of the AC at 15 amps, then use a 20 amp breaker circuit, not a 30 amp one. The undervoltage stayed there long enough to overheat components, cause high current draw, extreme phase angle.

__________________
If it ain't broke, don't fix it. Just build a better one.
Register to Reply
Guru

Join Date: Feb 2011
Posts: 7045
Good Answers: 206
#7

Re: Three Window air conditioners catch on fire

05/23/2015 7:27 PM

I'd fix your line voltage first

Register to Reply
Power-User
Engineering Fields - Control Engineering - Control Engineering Technical Fields - Education - Industrial Training Engineering Fields - Manufacturing Engineering - Manufacturing Training Engineering Fields - Electrical Engineering - Electrical engineering Training Engineering Fields - Instrumentation Engineering - Instrumentation Engineering United States - Member - New Member Engineering Fields - Energy Engineering - Become part of the larger group, change your world.

Join Date: Apr 2005
Location: St. Louis, MO. USA
Posts: 269
Good Answers: 1
#8

Re: Three Window air conditioners catch on fire

05/23/2015 8:13 PM

Where all 3 the same brand? What was the time between failures?

__________________
AB PLC Training onsite, On-Line, training software and more. BIN95.com
Register to Reply
Power-User
Engineering Fields - Electrical Engineering - New Member Engineering Fields - Power Engineering - New Member

Join Date: Mar 2012
Location: the sandbox
Posts: 340
Good Answers: 6
#9

Re: Three Window Air Conditioners Catch on Fire

05/24/2015 4:37 AM

they were all LG brand 2 ton units. model W24. I will research line voltage if that was a problem. Elec dept says 2 out of 3 had AFCIs installed and breakers were UL and to code, and breakers did trip, but too late to prevent a fire. As ignator said, maintenance dept had a role in this, but mainly that maintenance was virtually non- existent except for cleaning filters, and units were 8+ years old in a very dusty mid-east desert. Yes, I should write LG, and i will, with supervisor's permission of course. My overall opinion is even if breakers were to code, they did not prevent 3 fires, so "something" should have been done differently. And SolarEagle is right, I dont want to do unauthorized alterations to a manufacturer's design, and share blame for failures when i wasn't on the job........but otherwise a thermal relay (IEEE # 49) or a failure to start relay seems like a good idea ???

__________________
BSEE but always learning
Register to Reply
Guru

Join Date: Feb 2008
Location: Large hole formally occupied by furry woodland creature.
Posts: 3385
Good Answers: 97
#11
In reply to #9

Re: Three Window Air Conditioners Catch on Fire

05/24/2015 8:07 AM

Be sure to monitor line voltage at maximum worst case load.

__________________
CRTL-Z
Register to Reply
Guru

Join Date: Sep 2012
Location: Iowa, USA
Posts: 577
Good Answers: 50
#17
In reply to #9

Re: Three Window Air Conditioners Catch on Fire

05/24/2015 11:04 PM

So the breakers did trip, but only after the capacitor started burning. Seems like initial failure drew enough current that the breakers did not see this as arcing current.

Would be interesting to see a photo of the burned capacitors. I'm guessing once they burned to where air exposure allowed arcing, is when the breakers tripped.

I'm assuming this is a permanent split capacitor motor, so this capacitor is a start/run capacitor, and always in the circuit.

Seems like Andy German's solution to replace all the capacitors in the existing units would be prudent. 3 identical failures is showing a statistical trend.

Capacitors are most likely failing in voltage breakdown. You could go to the next higher voltage rating if you have room for this larger volume capacitor. But the problem, as others commented, is quality of dielectric failing over time.

__________________
ignator -
Register to Reply
5
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#10

Re: Three Window Air Conditioners Catch on Fire

05/24/2015 6:11 AM

I would place money on it being capacitor failures, not motor, there seems to be a lot of these cap failures around the last few years, even on CR4....

Caps dry out (is what I say!!) and lose their capacity, till the motor cannot run. It then overheats and bursts into flames....difficult to decide which came first.....burning motor or dead cap.....

Optically, the cap may appear to be normal even though its value may have diminished....or its resistive value is very low, either way is bad....

May I suggest that at the earliest opportunity, the A/C units (if any) that you still have running, should have their start caps either simply replaced (my method!) or tested in some good proper manner......though I don't believe that a cap measuring meter will be good enough for true safety, but thats just my opinion only, a more knowledgeable mind here may disagree completely....follow their thoughts then....

Nowadays I would suggest that every 4 years or so, such caps should be replaced as a matter of course during maintenance, rather than waiting for a fire....

High quality caps are best. Best quality are usually "Run" caps, not start caps (as you probably need!), but you may have trouble finding a Run cap of the Start cap value.....possibly.

It may be a good idea to have some sort of "fire" sensor/alarm, in or over each unit whether new or old....basic safety.....to be tested regularly.....fire is not funny!!

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply Good Answer (Score 5)
Guru
Popular Science - Cosmology - Let's keep knowledge expanding Engineering Fields - Retired Engineers / Mentors -

Join Date: Dec 2006
Location: North America, Earth
Posts: 4384
Good Answers: 104
#13
In reply to #10

Re: Three Window Air Conditioners Catch on Fire

05/24/2015 12:14 PM

GA Andy.

"....or its resistive value is very low,"

You mean its parallel resistance is too low or its series resistance is too high. This cannot be tested with simple digital capacitance meters that are common in handheld multimeters today. It requires a capacitance meter that also measures conductance.

__________________
“I would rather have questions that can't be answered than answers that can't be questioned.” - Richard Feynman
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#14
In reply to #13

Re: Three Window Air Conditioners Catch on Fire

05/24/2015 1:09 PM

I meant that if you used a high voltage Ohmmeter, you would probably read a relatively low value, not good..

Usually, a good cap of any type has a very high DC resistance, at least megohms...though depending upon construction, some have a higher resistance than others....

But I am not an expert on high voltage un-polarised motor start caps, rather mostly the reverse (pun intended)....I know enough to be dangerous!! There are people here that understand them far better than I....

Being nosy, I usually check them with a cap meter and then simply go out any buy a new one no matter what the meter says..... I find they are often a long way away from the marked value....

Funnily enough, it often fixes the problem....

Some things make a single phase motor run hot (I am sure there are more!) :-

1) Too low a voltage definitely or even too high, but that seldom happens in my experience!

2) Centrifugal switch is always shorted

3) Start cap is too low in value - dried out, motor fails to turn. Probably a run cap too if fitted, but I have never had that problem.....thats just a wild guess.

4) Bad bearings - mechanical problems.

Some of the problems are affected by the actual mechanical load that the motor physically drives.....even if the motor itself turns freely.

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru

Join Date: May 2006
Location: Placerville, CA (38° 45N, 120° 47'W)
Posts: 6007
Good Answers: 243
#15
In reply to #10

Re: Three Window Air Conditioners Catch on Fire

05/24/2015 1:30 PM

GA!

It's amazing how they often make cheap capacitors recently.

Apple computer had a major problem with cheap Chinese capacitors in their 2003-2004 G5 series Mac computers, which have virtually all died by now. Fortunately, I'm not aware of them causing any fires, and they haven't had the problem in more recent models.

My Carrier brand A/C is 48 years old, and still operating fine on the original caps. I did replace the fan motor a few years back, but the compressor is original.

This last year I helped a friend repair a 70 year old table saw motor. The insulation on some of the wiring became so brittle that it fell off and shorted out. I fully expected to have to replace the flat-pack capacitor, but to my amazement it was and is fine!

Thus the only reason these caps are failing is poor construction and/or selecting values with inadequate tolerance for handling higher temperature, voltage surges, etc.

__________________
Teaching is a great experience, but there is no better teacher than experience.
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#16
In reply to #15

Re: Three Window Air Conditioners Catch on Fire

05/24/2015 4:22 PM

Wow, so old and still fine!

Like me!!

The modern capacitor crap is simply awful!!

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Power-User
Engineering Fields - Electrical Engineering - New Member Engineering Fields - Power Engineering - New Member

Join Date: Mar 2012
Location: the sandbox
Posts: 340
Good Answers: 6
#12

Re: Three Window Air Conditioners Catch on Fire

05/24/2015 8:47 AM

GA for Andy Germany, made me think to replace the existing wet caps, "filled with vegetable oil" with dry film caps of the same value, like this one here

http://datasheets.globalspec.com/ds/992/VossLighting/6488609C-7BA4-4A1C-A85C-91313F65C06F

which is almost exactly perfect, I need 60 μF, this one is 55 μF

__________________
BSEE but always learning
Register to Reply
2
Guru

Join Date: May 2006
Location: Placerville, CA (38° 45N, 120° 47'W)
Posts: 6007
Good Answers: 243
#18
In reply to #12

Re: Three Window Air Conditioners Catch on Fire

05/24/2015 11:41 PM

That capacitor has a 240 V rating. That's fine if these A/C units run on 120VAC, but nowhere near enough if they run on 220 or 240VAC. The voltage rating of the caps needs to be significantly higher than the line voltage. Remember that 120VAC RMS has a peak voltage of nearly 170V, and 220VAC RMS has a peak voltage of roughly 310V. You want considerable leeway for variations in voltage, so a capacitor for use on a 120V line should be rated at 200V or higher, and one for a 220V line should be rated at 350V or higher.

There is a fairly good chance that the reason these caps are failing is because the designers didn't take this into consideration.

I have no idea how the demands on a ballast lighting capacitor compare with those of a motor start or run capacitor, but I suspect the heat and vibration levels are significantly greater on a motor.

__________________
Teaching is a great experience, but there is no better teacher than experience.
Register to Reply Good Answer (Score 2)
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#20
In reply to #18

Re: Three Window Air Conditioners Catch on Fire

05/25/2015 2:32 AM

Over many years I have seen many designs in electrics and electronics fail just through the point you made in your post.

GA.

Even 600 volt SCRs and TRIACs will fail regularly here, as we found out, when used on European mains, instead of US mains, where they worked fine.

I once had a massive job of de-soldering dozens (eventually hundreds really!!) of them and replacing them with 1000 volt devices, that simply worked!!!

May 1981, my first few days on the job in Germany.....you don't need a local language to solder!!!

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 14331
Good Answers: 161
#31
In reply to #18

Re: Three Window Air Conditioners Catch on Fire

05/28/2015 9:35 AM

Here is the NERC study on FIDVR (fault-induced delayed voltage recovery):

http://www.nerc.com/docs/pc/tis/FIDV_R_Tech_Ref_V1-1_PC_Approved.pdf

Especially pay close attention to figure 1, that reveals the voltage-time response in a system relying on capacitor banks to correct phase lag, and undervoltage after a substation trip, etc. Note the longer-term behavior where the voltage is considerably under-voltage. This leads to things like refrigerators, AC units, and televisions burning out.

To catch any UL-approved equipment on fire, one must "try really hard" - meaning that undervoltage must exist due to local supply overload and undervoltage that persists for hours.

__________________
If it ain't broke, don't fix it. Just build a better one.
Register to Reply
Guru

Join Date: May 2006
Location: Placerville, CA (38° 45N, 120° 47'W)
Posts: 6007
Good Answers: 243
#32
In reply to #31

Re: Three Window Air Conditioners Catch on Fire

05/28/2015 3:43 PM

Unfortunately, that link brings up a solid black page, and the download won't open in any of my PDF viewers.

__________________
Teaching is a great experience, but there is no better teacher than experience.
Register to Reply
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 14331
Good Answers: 161
#33
In reply to #32

Re: Three Window Air Conditioners Catch on Fire

05/28/2015 4:38 PM

OK, I just checked link, and it worked fine for me. You may be using the Cavalier version of browser (Windoos -2.6).

__________________
If it ain't broke, don't fix it. Just build a better one.
Register to Reply
Guru

Join Date: May 2006
Location: Placerville, CA (38° 45N, 120° 47'W)
Posts: 6007
Good Answers: 243
#35
In reply to #33

Re: Three Window Air Conditioners Catch on Fire

05/28/2015 7:15 PM

Well that was strange! I commonly use Firefox (on a Mac) for CR4, because it has the toolbar, while Safari does not. I just tried your link in Safari, and it works fine! Just in case, I did go back and try Firefox again, and it still does not. In fact Firefox does present a message saying "This PDF may not display correctly", so Firefox can detect something awry.

From first glance, that's a really interesting article; I'll have to study it more...

Thanks!

__________________
Teaching is a great experience, but there is no better teacher than experience.
Register to Reply
Guru

Join Date: Feb 2008
Location: Large hole formally occupied by furry woodland creature.
Posts: 3385
Good Answers: 97
#34
In reply to #31

Re: Three Window Air Conditioners Catch on Fire

05/28/2015 5:24 PM

Great article! A key sentence from it:

"The mechanical torque of the compressor for these units tends to remain relatively constant for the first few seconds which makes the motors more prone to stalling."

"these units" to mean single phase a/c units. The exception is the scroll type compressor.

__________________
CRTL-Z
Register to Reply
Member

Join Date: Sep 2013
Posts: 8
#19

Re: Three Window Air Conditioners Catch on Fire

05/25/2015 1:50 AM

window acs are not rated for 24x7 use. have appropriate additional capacity with cyclic timer to avoid continuous working

Register to Reply
Associate

Join Date: Jan 2009
Posts: 32
Good Answers: 1
#21

Re: Three Window Air Conditioners Catch on Fire

05/25/2015 10:42 AM

AC compressor motors typically have an overload within the circuit. 'Klixon' is a common name in these parts.A simple bimetal disc that warps (or unwarps) upon reaching a designed temperature opening the circuit.When cooled to 'normal' temps the disc closes the circuit.

Maybe the 'Klixon' contacts became welded closed (high V & or I)

Any recent electrical work @ the facility? Maybe someone decided a 480 leg to ground would suffice for a 240 pair?? Or perhaps grabbed the 'stinger' ???

Someone's gonna get killed if this isn't immediately addressed-& I don't mean by posing a question to CR4.

Your posting here has declared your awareness of this situation.

Tada

Register to Reply Score 1 for Good Answer
Guru

Join Date: Oct 2014
Location: Hemet, Land of milk and honey.
Posts: 2366
Good Answers: 36
#22

Re: Three Window Air Conditioners Catch on Fire

05/25/2015 11:00 AM

From what I could find, the cap may be a, " 370v 45 ". Not enough info provided to be accurate.

Register to Reply
Guru
United States - Member - New Member Engineering Fields - Power Engineering - New Member

Join Date: Sep 2006
Location: California, USA, where the Godless live next door to God.
Posts: 4658
Good Answers: 796
#23

Re: Three Window Air Conditioners Catch on Fire

05/26/2015 1:52 AM

You seem hyper focused on the "failure" of the AFCI breakers. Note that AFCI does not mean All Fire circuit interrupters, they mean Arc Fault Circuit interrupter.If your motor overloaded or the caps failed WITHOUT causing an arc, the AFCI would not trip. It's not designed to.It is still a Thermal Magnetic Circuit Breakers, so if there is no direct short circuit, it is only the thermal trips that take it off line. If your capacitors failed, that's what I would expect to happen. The fact that they a) failed and b) caught on fire before a CB tripped is a serious problem WITH THE AC UNITS, but the circuit devices ahead of it were likely just doing their job.

If you are interested in pursuing this further, do a search on the term "capacitor plague", a well known and documented problem that took place a few years ago in which an Asian capacitor mfr stole the "secret sauce" formula for the electrolyte from another, only to discover later that it was a fake. Unfortunately, the fake electrolyte made it into literally billions of capacitors and out into the marketplace for years before it was discovered, long after recalls could be effectively accomplished. The legacy continues to this day.

__________________
** All I every really wanted to be, was... A LUMBERJACK!.**
Register to Reply
Power-User
Engineering Fields - Electrical Engineering - New Member Engineering Fields - Power Engineering - New Member

Join Date: Mar 2012
Location: the sandbox
Posts: 340
Good Answers: 6
#24

Re: Three Window Air Conditioners Catch on Fire

05/26/2015 2:06 AM

Followup:

as part of the annual or semi-annnual PMs, the HVAC dept will now be doing two new things: 1. changing out the caps, and 2. megging out the compressor motors.

__________________
BSEE but always learning
Register to Reply
Guru
Popular Science - Weaponology - New Member Safety - ESD - New Member Hobbies - Fishing - New Member

Join Date: Sep 2006
Location: Near Frankfurt am Main, Germany. 50.390866N, 8.884827E
Posts: 17996
Good Answers: 200
#26
In reply to #24

Re: Three Window Air Conditioners Catch on Fire

05/26/2015 3:51 PM

Great moves, well done getting the implementation passed by your company.

__________________
"What others say about you reveals more about them, than it does you." Anon.
Register to Reply
Guru
Safety - Hazmat - New Member United States - US - Statue of Liberty - New Member Engineering Fields - Chemical Engineering - Old Hand

Join Date: Mar 2011
Location: Lubbock, Texas
Posts: 14331
Good Answers: 161
#27
In reply to #24

Re: Three Window Air Conditioners Catch on Fire

05/26/2015 4:08 PM

Maybe you should also install a line voltage reference, and record line voltage just to be smart.

__________________
If it ain't broke, don't fix it. Just build a better one.
Register to Reply
Power-User

Join Date: Jun 2010
Location: Kolkata, West Bengal, India
Posts: 172
Good Answers: 1
#36
In reply to #24

Re: Three Window Air Conditioners Catch on Fire

05/30/2015 1:54 PM

Also please measure presence of harmonics in the electrical line to avoid caps failure/burning.

Manindra.

__________________
Manindra
Register to Reply
Power-User
Engineering Fields - Electrical Engineering - New Member Engineering Fields - Power Engineering - New Member

Join Date: Mar 2012
Location: the sandbox
Posts: 340
Good Answers: 6
#30

Re: Three Window Air Conditioners Catch on Fire

05/28/2015 4:17 AM

Andy G, your right, the most amazing part is that HVAC cooperates with this solution, even tho it involves extra work for them

__________________
BSEE but always learning
Register to Reply
Power-User
Engineering Fields - Electrical Engineering - New Member Engineering Fields - Power Engineering - New Member

Join Date: Mar 2012
Location: the sandbox
Posts: 340
Good Answers: 6
#37

Re: Three Window Air Conditioners Catch on Fire

05/30/2015 9:57 PM

the latest: another one overheated, the room resident smelled something (almost) burning, and turned it off before there was an actual fire, so we will take it apart tomorrrow and i will post results here.

__________________
BSEE but always learning
Register to Reply
Guru

Join Date: Feb 2008
Location: Large hole formally occupied by furry woodland creature.
Posts: 3385
Good Answers: 97
#38
In reply to #37

Re: Three Window Air Conditioners Catch on Fire

05/31/2015 10:23 AM

Its getting too hot in here to think of anything but line voltage or conductor capacity. I'd use an exclamation point, but somebody used them all up.

__________________
CRTL-Z
Register to Reply
Register to Reply 38 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

1capybara (7); Andy Germany (5); BIN95 (1); dkwarner (4); Fredski (1); hrk (1); ignator (2); James Stewart (5); JRaef (1); manindra (1); Mr Fixit (1); NotUrOrdinaryJoe (1); RAMConsult (1); SolarEagle (1); StandardsGuy (1); tonyhemet (1); Unredundant (4)

Previous in Forum: Bucket Elevator Sensors in Cement Plant   Next in Forum: Help with designing a Load Cell with DMS

Advertisement