A/C causing clocks to reset and lights to flicker

[ActionDave]

Jim, give me a call at the shop tomorrow if you get a minute.

That would be easier if you would post your phone number.

 

[hbiss]

191006-2225 EDT

hbiss:

Ran an experiment on an LED. With a 2% change in excitation of current which is the necessary way with an LED. I did not visually see a change in intensity even with a long pulse. This was a red LED. A full wave rectified signal was used.

By comparison the 15 W incandescent was noticeable with the 2% voltage change at my 60 mS duration.

.

Interesting. I believe some LEDs use a phosphor to produce the color and there may be an "afterglow"? Interesting also because you can tell when a vehicle uses LEDs for the turn signal and brake lights because of the instantaneous transition from on to off. Not like the ramp up and ramp down illumination from an incandescent. Quite noticeable.

-Hal

 

[gar]

191012-1254 EDT

hbiss:

My LEDs are non-phosphored plain old pilot light type red LEDs.

Some more experiments on 120 V 15 W incandescent flicker. This is a work bench test.

Two bulbs side by side. One on each phase. Load change on one phase about 10 A, a space heater.

Initially both voltages are within 0.2 V of each other. Loading one phase with about 10 A its voltage drops about 4 V, and the other phase increases about 2 V. The 4 V change is detectable, but probably not if you were not looking at the bulb, and expecting the change. Reading the newspaper you might not notice the change. Especially when the signal is not known exactly in time.

I give up. This website software is junk, and never should have been put online until it was debugged. It is constantly kicking off today, as well as many other times, and even though it saves my post as I am composing, it then sometimes destroys some of the saved post. The part that is destroyed has been known to have been saved because it has been previously reloaded.

.



​​​​​​​

 

[hillbilly1]

Since the voltage balance is good, and even with a 10 kva that a lot of poco’s use, I don’t think that load is abnormally high. I’m betting it’s on the hv side of the transformer, bad fuse holder, or line tap wasn’t tightened down most likely.

 

[Dennis Alwon]

I remember years ago hearing that it was better to have the conductor to the a/c as small as possible. They were saying that the smaller conductors would limit the amount of inrush current and thus less flickering. I am positive I read it on this forum. Am I really losing it that bad?

 

[readydave8]

Yes Dennis I remember reading that also, and suspect it was on this forum

 

[Russs57]

I'm with StarCat. I don't know when and why so many companies stop using start caps on residential AC's. I'd rather get the factory parts than a universal "hard start". Make sure you have an "anti-recycle" time delay.

For the cost of a cap, a TD relay, and a high and low pressure sensor you can greatly increase the life expectancy of your central AC (I also favor an expansion valve over a piston)....and you can run it with a much smaller generator.

For problems like this I like to divide and conquer. For example, if you disconnect POCO and a 7.5 KW portable generator runs the AC fine and the clocks don't reset chances are high your problems are exterior to the house. This assumes you can reliably recreate the problem.

 

[GoldDigger]

I'm with StarCat. I don't know when and why so many companies stop using start caps on residential AC's. I'd rather get the factory parts than a universal "hard start". Make sure you have an "anti-recycle" time delay.

For the cost of a cap, a TD relay, and a high and low pressure sensor you can greatly increase the life expectancy of your central AC (I also favor an expansion valve over a piston)....and you can run it with a much smaller generator.

For problems like this I like to divide and conquer. For example, if you disconnect POCO and a 7.5 KW portable generator runs the AC fine and the clocks don't reset chances are high your problems are exterior to the house. This assumes you can reliably recreate the problem.

If we are going to drift a bit into improving starting performance of residential A/Cs, among other things for generator operation, look into inverter driven mini-split A/C or heat pump units. Essentially a dedicated VFD in each unit.

 

[MAC702]

...you can greatly increase the life expectancy of your central AC (I also favor an expansion valve over a piston)...

The other things you mention increase life expectancy, yes, but the TXV increases efficiency AT THE RISK of life expectancy. I've only been repairing residential and light commercial ACs for about 10 years. In that time, I've never seen a piston go bad, but have had to replace maybe 50 TXV's, at substantial cost and downtime to the client.

 

[kwired]

I'm with StarCat. I don't know when and why so many companies stop using start caps on residential AC's. I'd rather get the factory parts than a universal "hard start". Make sure you have an "anti-recycle" time delay.

Not sure I have ever seen one with a start capacitor other than aftermarket hard start kits. They do not need nearly the starting torque if you ensure the pressure is equalized before starting, simple delay timer that costs $10 or less helps ensure that will happen.

I have seen start capacitors (and usually controlled by potential relay) on commercial refrigeration units but not on typical residential air conditioning units.

 

[MAC702]

...I don't know when and why so many companies stop using start caps on residential AC's. I'd rather get the factory parts than a universal "hard start".....

What few models I've seen that come with a start capacitor use the same "universal hard start" kits I can buy separately.

 

[RumRunner]

I'm with StarCat. I don't know when and why so many companies stop using start caps on residential AC's. I'd rather get the factory parts than a universal "hard start". Make sure you have an "anti-recycle" time delay.

For the cost of a cap, a TD relay, and a high and low pressure sensor you can greatly increase the life expectancy of your central AC (I also favor an expansion valve over a piston)....and you can run it with a much smaller generator.

For problems like this I like to divide and conquer. For example, if you disconnect POCO and a 7.5 KW portable generator runs the AC fine and the clocks don't reset chances are high your problems are exterior to the house. This assumes you can reliably recreate the problem.

For a residential size (minimum) A/C-- expansion valves are essential part of a functional refrigerated A/C system. The only time you can forgo expansion valves is when using a refrigeration unit designed for small units like portable coolers. This doesn’t need compressors like piston or rotary type.

These are units used by medical personnel for storing medication that needs to be at a certain temperature like vaccines for poor countries in hot climates.

You only need to put it on top of wood burning stove or even dried camel dung. No sh*t.

Another methodology for refrigeration is the absorption method. This also doesn’t need compressors. So, there is no noise or the associated flickering nuisance or the scourge of inrush current that would cause voltage sag in marginal power supply systems.

Absorption type units are mostly used in RVs where power is not always available to run compressors. I have one in my RV. . . it will run or either propane, electric (power grid) or solar inverter. With an array of deep cycle batteries it will run my fridge until the next sunlight. Draws less than 200 watts.

 

[MAC702]

My assumption was that he was referring to a thermostatic expansion valve (TXV) in lieu of a piston as the metering device for expanding the refrigerant into the evaporator. Yes, the refrigeration cycle on these types of machines must use something for metering. But it doesn't have to be a more efficient TXV. It can simply be a fixed orifice piston that will probably never fail.