refrigerator damage from ST head???

[M61hops]

Hey cschuerm, where was the condenser on the fridges that died?  Were they underneath and cooled by a fan, or mounted on the back and cooled by convection air flow?  The condensers that are down under and fan cooled clog with pet hair, lint and dust surprisingly fast and cause the compressor to run much hotter than they were designed for.  Some of the new energy efficent fridges seem like the compressors are in reality too small for the job and I've seen a few die at low hours.  Maybe the THD issiue added to a compressor that is already running too hot could be the problem  ??  I just would not expect that an ST head could hurt a refrigerator, but now I'll keep an eye on mine if I start to run long hours  !                              Leland

[PaulMoffenger]

Perhaps some of the "Off Gridders" could offer some insight or statistics on ST power and appliance life vs. failure?

Paul

[jzeeff]

You should be able to put a Kill-a-watt on it with utility power and with ST power and see if there is any KWH or KVA difference.  If it heats up more, it has to draw more power (or do less work).

[jzeeff]

Other inductive loads (vs the generator) could also cause problems by creating harmonics and surges.   

I've concluded that one really needs to use a surge suppressor - if you disconnect the generator and you have inductive loads running, these loads become generators and they aren't limited to normal voltages - so you can get some big voltage spikes.

[SHIPCHIEF]

You shouldn't have to have an oscilloscope to use an ST head 
When we had our big blackout in 2007, my governor wasn't good. I had a lot of Frequency / voltage excursions during that 5 days.
My 1970's vintage Yamaha stereo receiver/amp crapped out. Could have been time for it to go, could have been high or low voltage. Could have been 'dirty power'.
I'm looking at a 15 Kw LIMA 12 wire for sale locally. It's more expensive 'used & ugly' than my ST-12 was new. I guess you get what you pay for sometimes.

[cujet]

Consider that the ST waveform is not the only power quality issue.

The combustion event on the listeroid causes the generator head RPM to be unsteady at about an 11HZ freq. This is a major factor in my power problems.

Chris

[SHIPCHIEF]

I wonder if we can assign risk catagories?

1) That shouldn't be a problem with:
Electric range/oven
Electric water heater
Incandescent light bulbs
Universal motors (hand drill, electric lawn mower)
portable plug in heaters and hair driers.
OTL start induction motors

2) Less forgiving on;
Condenser start induction motors

3) Problematic with:
Microwave oven
Inverters

How about synchronous motors like old fashioned electric clocks?
Just a thought...

[Tom]

Our high efficiency Kenmore has lived through a winter and a half of 6/1 - st5 power with out a glitch. It has also been run for many hours from an Onan RV generator and a Tract SW2512 inverter.

[mobile_bob]

i think we may be using the rule of small numbers to dictate our reactions

without knowing what is happening to kill the old fridges its hard to point a finger at the st head for sure?

or maybe we shouldn't gage all st heads because of one installation that has killed 3 fridge's

we don't even know but what it might be something else, a bad breaker? that has a voltage drop across it at
higher amperages and drops the voltage? not impossible
maybe even a bad wall socket that can't deliver the needed amps for startup without a large voltage drop?
wouldn't be the first time that has happened i bet.

maybe even a loose connection in the st head to the ouput cable? maybe a weak leg? maybe a weak ground/neutral?

point being maybe a full analysis is in order before we blame it on the st head?

it just seems like alot of folks use the st head without major issues, like killing major appliances
one would think this problem if it is the fault of the st head, would have come up at least a few times here
with all the folks using the darned things?

maybe a load test needs to be done on the st head in question, with another appliance using the same wall receptical
that is somewhere near the same amp draw as the starting current of a typical refer motor on startup? using a voltmeter
to watch and see if there is a large drop, brownout condition or some other wierd anomoly?

maybe in the end it is just a bad st head, thats possible, there certainly are bad first world heads being reported on the net.
from a few kva to several 100's of kva. so that might be the problem?

it just seems odd that the OP was the unlucky one to have 3 fridges fail on st power in a narrow timespan
nobody is that unlucky and just had 3 fridges that died of old age like dominoes falling.

perhaps a killawatt meter is fast enough to catch the event when the fridge is starting, i would give it a try
to see if the volts drop below ~108vac while the fridge is starting (fridge usually take a couple seconds to start
so i would think the killawatt would respond quick enough, or use an analog meter to measure the voltage at the receptical)

if the voltage drops to far, i would be backing up the system and looking next to the breaker that supplies the fridge and see
if the volts drop coming out, if so i would move to the input side to see if it drops if not you got your problem a bad breaker
if it still drops you gotta backup further and keep testing.

at some point you will be back at the head,

if the volts stay upwards of 110 or better during startup, and the frequency doesn't collapse (which it couldnt and still maintain
voltage) then maybe we gotta look at harmonic content causing heating?

hell i don't know!

but i wanna know!

as i am sure most folks here want to know, so here is an opportunity to get to the bottom of this issue before it costs others
damage to appliances, especially if it is something we can learn from and do something proactive about it.

seems like a reasonable approach?

bob g

[xyzer]

I had a power outage once and it killed the fridge, fax machines, Satellite receiver....and so on....It took awhile to figure out what it killed! After a week soft ice cream was my first clue...the TV didn't take long to figure out. My new rule if the grid flickers run for the main!  Maybe they were already dying when you transferred?! Lots of outages ....why so many?........Around here the score is ST $0.00 Grid $1800.00 ..... just internet thoughts.......
Dave   

[M61hops]

I really doubt that there is anything about an ST head's power that could kill a fridge compressor  !  Maybe if the frequency dropped a lot and for a long time the start capacitor or overload switch could burn out.  Both are cheap and easy fixes!  Having the motor windings fail is a pretty rare occurrence, that's what the overload switch is there for, to protect the windings  ! It would nice to check the windings on all 3 compressors, I'd bet that at least 2 of the 3 motor windings are OK and probably all 3 are still good  !  There are many reasons that refrigerators stop keeping food cold but in my experience it is almost always something cheap and / or simple to fix and it is quite rare to find a failed compressor winding.  Windings do fail sometimes but in my experience somebody defrosting the freezer with a sharp object is a more common cause of death than failed windings in the compressor  : !  However, I've had 2 run windings fail open while I was working on a fridge  !  And once, after a power outage I happened to be sitting near my fridge when the grid came back on and my fridge started making a noise I've never heard before and the whole refrigerator started walking out of it's alcove  !!!  I jumped up and turned it off, I don't know what would have happened if I'd left it alone.  I puzzled over what could be going on and I'm still not sure what was happening.  I turned it back on after a minute or so and it worked fine and has for the last ten years.  Maybe was very low voltage  ?   My .03 worth!     Leland

[europachris]

Are you sure it's the compressors that are dead?  Most newer fridges such as yours are run by circuit boards that handle defrost timing, temperature control, icemaker filter replacement time, etc.  As are most consumer electronics, the boards are cheaply designed using the minimum quality to do the job.  It doesn't take much to kill them, even though the compressor and fans are usually pretty robust as long as the condenser is kept clean.  I keep a section of that fluffy blue roll filter media behind the intake grate at the bottom of our Kennmore side by side.  2/3 of the bottom is intake, the other 1/3 exhaust.  I remove the grate and vacuum the filter about once a month and with two English Cocker Spaniels, it is FULL.  At our previous home I wasn't smart enough to use the filter material, so I had to wheel out the fridge every 6 months and vacuum up enough fur and dust to make at least another complete dog. 

Conversely, I recall the old Whirlpool top freezer model I had growing up in the 70's where my Mom would take everything out of the freezer and put in a pan of hot water to thaw the ice quickly to defrost.  But, with no moving parts except the compressor, I bet that thing would still be going today, and the rear mounted condensers hardly ever required cleaning.  It was QUIET, too.

Now it seems everything is Chinese.  I bought a 8000 BTU A/C unit for our detached garage/shop the other weekend on sale.  Whirlpool - Made In China.  It's a nice unit - electronic control with remote, and the price was right $159.  But like most of the reviews I read on current A/C units, it's LOUD, even on low, and it's fan noise, not compressor noise.  On high it sounds like it's at takeoff power.  20 years ago I had a 6000 BTU Emerson "Quiet Kool" in my bedroom.  Made in the USA, naturally, and it indeed was quiet.  But I bet even back then it cost a lot more than $159 iin 1980's dollars.   Maybe not as efficient as new units, but with mechanical controls (reliable - easy to fix) it would be still going today.  But I digress.....

Related to this - I do notice that when I was running on generator power (Markon 2-pole 3.2kW brushless), motors such as ceiling fans hummed louder than usual, so even out of a quality generator head, the power isn't as clean as utility.  But 8 hours of gen power didn't seem to hurt the fridge or freezer and that was two summers ago.  Haven't needed the gen since.

Chris

[listeroil]

Are fridges not inductive loads that should be adjusted with a capicitor to get the correct PF reading whilst being run on a generator.

Mick

[Jim Mc]

Consider that the ST waveform is not the only power quality issue.

The combustion event on the listeroid causes the generator head RPM to be unsteady at about an 11HZ freq. This is a major factor in my power problems.

Chris

That's where I'd put my money.  The cyclic variation  in frequency (and voltage) will cause a similar variation in the current of an induction motor, and I could imagine how that would result in a  higher value of RMS (root mean square) current draw in a motor, even though the average current is the same as when powered from the mains.  The more I think this over, the more surprised I am that we've not seen this happen before...

[Wizard]

11hz do you mean periodic oscillation of frequency at that 11Hz?  With massive flywheels the oscillation should not be that big like 2 to 5hz spread around 60Hz even at that 11Hz.  Shouldn't be a problem, even that oscillation at 11Hz is not high frequency enough for a induction motor.  What is most sensitive is waveform quality.  Jagged waveforms from a ST is multiplies of frequencies added together even it is 60Hz.  Any spikes, sharp corners etc *are* noise and high frequency because of sharp transitions is what overheats and causes losses.

Had a particular SMPS design that it has POOR design that is overheating a diode and killing the bulk filter capacitor on the 13V, due to waveforms not smooth due to it's running in wrong spot based on IC and particular transformer.  When they changed the IC to different IC in the SMPS even kept same basic design of SMPS, overheating went away.  Irony of this, all other outputs like 60V, 135V, 18V capacitors unaffected!
Second irony is same SMPS had no problem in same chassis if guide plus module is not used therefore removes the need for medium power standby.

Cheers, Wizard