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Login to post Forums » Off-topic discussion » Losing time??

April 20, 2011 1:34 p.m. GrantMLS New Reader

OK This is weird - atleast I thnk it is..

We have a pretty new stove, and a very new microwave. Both where plugged in around 8 monthes ago when we finished with the kitchen remodle - plugged into the same outlet - It's wred along with 4 more outlets and into a single breaker.

My wife made cookies, and burnt them claming to set the timer on the stove for 20 minutes - but when it went off it was more like 35 minutes. We looked at the clock and it was about 3 hours 38 minutes off. Odd - then we noticed the microwave was about an hour and 15 minutes off.

I know I set both the mircowave and the stove to the same time. When the power goes out which hasn't happened n a long time - both flash 12:00 and do nothing till set.

I HIGHLY dout they take the 60hz pulse of the AC for the clocks - though knowing our power company I am sure it goess off phase but does anyone really use that for clocks?

What would make them go wrong?? (They are digital) ok enough typing..
April 20, 2011 2:16 p.m. DrBoost SuperDork

April Fools joke?
April 20, 2011 2:20 p.m. tuna55 Dork

I really really doubt they go far from 60Hz. Get a silly scope and check?
April 20, 2011 2:26 p.m. triumph5 Dork

Have you recently plugged something new into one of those 4 other outlets on the same breaker?

I do know that "brown outs" will effect appliances in some peculiar ways. Has the power company been in the neighborhood making upgrades or expanding services. New business in the area that requires lots of power--or neighbor?
April 20, 2011 2:29 p.m. bludroptop SuperDork

Dood! Climb in your oven, set the clock for 1998, buy stock in E-Bay!
April 20, 2011 2:33 p.m. GrantMLS New Reader

In reply to triumph5:

not that i am aware off - nothing new and havnt had a brown out. Nor have we had any issues with the mircowave cooking..
April 20, 2011 2:36 p.m. GrantMLS New Reader

In reply to bludroptop:

good plan.. or go back farther and buy a 510 and hide it someplace...
April 20, 2011 3:10 p.m. tuna55 Dork

GrantMLS wrote:

In reply to bludroptop:

good plan.. or go back farther and buy a 510 and hide it someplace...

Why a 510? Go get one of those crazy undesirable Hemi Cudas, or stop that guy from sawwing the wing off of his Dodge Daytona, or buy one of the Cobra Daytona Coupes that the old man was selling for the crazy high price of 5k.
April 20, 2011 3:29 p.m. GrantMLS New Reader

i guess thats my problem - i dont think big enough... sure be nice to have a few gallons of gas for 50 cents..
April 20, 2011 4:21 p.m. stuart in mn SuperDork

I assume the clocks on both appliances are digital? That would indicate they are most likely running off quartz crystals, and not 60hz from the wall outlet.

That doesn't mean they are necessarily going to be spot on (I have a clock radio that loses a few minutes a month for some reason) but they shouldn't be off by that much.
April 20, 2011 4:55 p.m. iceracer Dork

Have you checked the outlet voltage ?
April 20, 2011 5:37 p.m. Jay SuperDork

One time when I was a teenager I decided I wanted a 24h digital clock for my bedroom so I bought one on a family holiday in Germany and brought it back to Canada with me. It ran fine on half its rated voltage but sure enough took 50 seconds to count a minute. So apparently some cheap clocks do use the wall frequency for time keeping. I kept it in a box in the basement and forgot about it... until 10 years later when I moved over to Germany full-time. Works fine now. I still even have the box with the 5.99 DM price tag on it.

I seriously doubt the one in a major appliance would do that though, and losing 15 minutes over a 20 minute count sounds too extreme for just fluctuations in the net power frequency. I'd start checking your home wiring first.
April 21, 2011 9:21 a.m. GrantMLS New Reader

voltage was 112 ish..my scope is in my parents basement about 800 miles away so won't be able to look at that for a while. I reset both of them this AM to see how long it takes toget off track.

Basically its somthing to do other then finish the remodleing of the bathroom
April 21, 2011 11:52 a.m. cwh SuperDork

112 is real low for house voltage. Mine runs around 122 to 125. Something funky going on , but you already knew that.
April 21, 2011 12:11 p.m. tuna55 Dork

From Wiki:

Long-term stability and clock synchronization

Regulation of power system frequency for timekeeping accuracy was not commonplace until after 1926 and the invention of the electric clock driven by a synchronous motor. Network operators will regulate the daily average frequency so that clocks stay within a few seconds of correct time. In practice the nominal frequency is raised or lowered by a specific percentage to maintain synchronization. Over the course of a day, the average frequency is maintained at the nominal value within a few hundred parts per million.[18] In the synchronous grid of Continental Europe, the deviation between network phase time and UTC is calculated at 08:00 each day in a control center in Switzerland, and the target frequency is then adjusted by up to ±0.01 Hz (±0.02%) from 50 Hz as needed, to ensure a long-term frequency average of exactly 24×3600×50 cycles per day is maintained.[19] In North America, whenever the error exceeds 10 seconds for the east, 3 seconds for Texas, or 2 seconds for the west, a correction of ±0.02 Hz (0.033%) is applied. Time error corrections start and end either on the hour or on the half hour.[20][21] Real-time frequency meters for power generation in the United Kingdom are available online - an official National Grid one, and an unofficial one maintained by Dynamic Demand.[22] [23] Smaller power systems may not maintain frequency with the same degree of accuracy.
April 21, 2011 12:32 p.m. GrantMLS New Reader

I think I am going to have to buy a new fluke to get to the bottom of this.. yeah going to have to put off the bathtub install for a while..
April 21, 2011 12:48 p.m. Toyman01 SuperDork

The power company will fluctuate some. Usually not more the 2-3 hertz in either direction. I wouldn't think that would be enough to make the clocks wrong. That much load on one circuit I would guess voltage drop when everything is on. Get a multi-meter and check. You can probably get one that will check frequency as well. Unless you need to use it every day I wouldn't spend the money for a Fluke. HF has several that work pretty good. I use a Fluke at work and a HF at home.
April 21, 2011 12:58 p.m. Ian F SuperDork

cwh wrote:

112 is real low for house voltage. Mine runs around 122 to 125.

Not really. Residential voltage usually varies between 110 and 120, depending on the local utility, which is why most consumer electonics and appliances have 115V listed on the back with a +/- allowance. Anything above 120 is actually rather high.
April 21, 2011 1:00 p.m. TRoglodyte Reader

I thought I read once that a microwave is supposed to be on its own circuit breaker?
April 21, 2011 1:06 p.m. GrantMLS New Reader

1100 watts.. its on a 20 amp braker (so at 112v ~10amps). and correction - I was thinking of our old oven that was gas - the new ones ie Electric so its on its own 2 pole 50 amp breaker. so really the microwave is on its own.
April 21, 2011 1:19 p.m. Ian F SuperDork

It could be a bunch of different things: How old is the wiring? If it's aged and corroded to the point where it's addiing resistance, then it may cause electronic weirdness. Bad ground or neutral connection. Ditto.
April 21, 2011 2:27 p.m. Conquest351 Reader

My convection oven and regular oven do that. The convection oven is consistantly faster than the regular oven. I'll have to reset it about every 2-3 weeks, otherwise it's about 10-15 mins faster.
April 21, 2011 2:35 p.m. cwh SuperDork

Good idea to check your meter. I have a "good" meter from my installer days that shows my house voltage at 160. FUBAR.

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