When the world doesn't understand energy and power

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The discussion centers on a worksite office experiencing flickering lights when a coffee maker is used, likely due to high inrush current and voltage sag from a long extension cord. Suggestions include using an NTC thermistor to limit inrush current, though safety and technical expertise are considerations. The use of a heavier gauge extension cord is recommended to reduce voltage drop, with options like 8 or 6 AWG being discussed. Participants also suggest testing the voltage drop when the coffee maker is turned on and considering a separate circuit for the coffee maker to alleviate the issue. Overall, addressing the power supply setup is crucial for resolving the flickering lights problem.
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Maybe you guys can help me figure out what I'm looking for...

I have a worksite office that runs off an extension cord. The coffee maker pulls enough power when it turns on that it flickers the light. I am looking for an AC equivalent to a DC inductor. Basically I would like a device that when the coffee maker asks power, it slowly ramps to full power over a couple seconds.

My crude solution was to run a 12v battery with an inverter and a charger to isolate it from the system, but that seems like a lot of work and expense.

Thanks
 
fpjeepy said:
The coffee maker pulls enough power when it turns on that it flickers the light.
That seems weird to me. I wouldn't expect the input to the coffee maker to have a high inrush current. What model is it?
fpjeepy said:
I have a worksite office that runs off an extension cord.
If you plug it directly into the wall socket with no extension cord, the flicker doesn't happen? What type of cord is it, and how long is it?
fpjeepy said:
Basically I would like a device that when the coffee maker asks power, it slowly ramps to full power over a couple seconds.
One such device is an NTC (negative temperature coefficient) thermistor. We use them to limit inrush through relays to capacitive loads (to keep the relays from getting fried by the high inrush current). But unless you know what you're doing electronics-wise, that probably isn't a solution for you.

https://product.tdk.com/en/products...c-limiter/technote/img/apn-ntc-limiter_01.png
1571165925808.png
 
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berkeman said:
That seems weird to me. I wouldn't expect the input to the coffee maker to have a high inrush current. What model is it?

If you plug it directly into the wall socket with no extension cord, the flicker doesn't happen? What type of cord is it, and how long is it?

One such device is an NTC (negative temperature coefficient) thermistor. We use them to limit inrush through relays to capacitive loads (to keep the relays from getting fried by the high inrush current). But unless you know what you're doing electronics-wise, that probably isn't a solution for you.

https://product.tdk.com/en/products...c-limiter/technote/img/apn-ntc-limiter_01.png
View attachment 251176
Mainstays 512841 $10 from Walmart

There is a long 10 or 12 gauge cord that runs to the shed. Inside I have a few lighter cords and power strips that it is running though. I haven't tried moving it around to see if the power strips are causing the issue.

I'm not an electrician, but at this point my options are; leave the coffee pot 50 yards away on a different circuit exposed to construction dust etc, drink cold coffee, or makeshift something cause I can't deal with the lights anymore. [sips cold coffee] $2 NTC thermistor on Amazon sounds like a cheaper option than my battery idea.
 
This pdf contains the owner's manual. This excerpt allows an extension cord with some restrictions.
If an extension cord is used:
-The marked electrical rating of the extension cord should be at least as great as the electrical rating of the appliance.
-If the appliance is of the grounded type, the extension cord should be a grounding 3-wire cord;

.Polarized plug• This appliance has a polarized plug (one blade is wider than the other). To reduce the risk of electric shock

No mention of power strips but adding lighter extension cords to the heavy likely exceeds the specs. I own a similar non-Walmart inexpensive coffee pot from Target. My owner manual prohibits extension cords. Mine has a two-prong polarized plug 110V AC.

Idea for one or two coffee drinkers: plug the coffee pot directly in the "main shed", brew and transfer to a thermos carafe for your remote work area. Unplug and clean pot for next use.

Some inexpensive coffee pots come with a stainless steel thermos carafe that you carry away after brewing, presuming you are the primary coffee brewer.
 
fpjeepy said:
$2 NTC thermistor on Amazon sounds like a cheaper option than my battery idea.
Yeah, but I haven't found any that are pre-packaged as a module so far. You would need something that had safety agency markings on it to be sure it was safe. The suckers get pretty hot too, so you have to be careful about thermal management in their applications.
fpjeepy said:
The coffee maker pulls enough power when it turns on that it flickers the light.
And maybe I misunderstood -- do you mean that the lights flicker the whole time the coffee pot is on (heating and/or brewing)? Or just briefly when you turn it on?

Since you say you're fed up with the "flickering lights", now I'm guessing that they flicker the whole time the pot is on, due to voltage sag caused by the long distribution cord...?

Also, are the lights incandescent, flourescent, or some other type?
 
berkeman said:
I wouldn't expect the input to the coffee maker to have a high inrush current.
It happens when the heating element is still cold and has low resistance.

'AC inrush current limiter' is common in DIN rail version, but rare as 'plug' or any other easy to use form. I could find some, but it is rare. Also not really cheap. Maybe a beefier extension cord would be cheaper.

link1
http://www.ameritron.com/Product.php?productid=ICP-120
 
fpjeepy said:
Maybe you guys can help me figure out what I'm looking for...

I have a worksite office that runs off an extension cord. The coffee maker pulls enough power when it turns on that it flickers the light. I am looking for an AC equivalent to a DC inductor. Basically I would like a device that when the coffee maker asks power, it slowly ramps to full power over a couple seconds.

My crude solution was to run a 12v battery with an inverter and a charger to isolate it from the system, but that seems like a lot of work and expense.

Thanks
Can you borrow a voltmeter from someone at the worksite, or enlist their aid for a couple of minutes?

Measure voltage at the coffeepot outlet with the pot turned off.
While continuing to measure voltage, turn the pot on and observe how much the voltage droops.

If it drops a lot, then a larger AWG extension cord may do the trick, but 50 yards (150 feet) is a long run, and it depends on how many amps the other loads pull. The coffeemaker alone is 900W (7.5 amps at 120V). An 8 AWG extension cord may be enough, but a 6 AWG extension might be necessary.

Problem is, I don't know if 6 AWG extensions are commercially available with a 120V/20A plug and receptacle.
 
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fpjeepy said:
There is a long 10 or 12 gauge cord that runs to the shed. Inside I have a few lighter cords and power strips that it is running though. I haven't tried moving it around to see if the power strips are causing the issue.

You are running an office - off of a single long extension cord? -- That is the problem. How long? What are the other loads in your office.

Can you run a separate cord for the Coffee maker?
 
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Windadct said:
Can you run a separate cord for the Coffee maker?
This is absolutely the easiest solution if you can do it. I bet the coffee maker won't care about a some undervoltage ...just be sure the cord doesn't overheat (you could test a short version of the same gauge to be sure before you get the long one...how big is the appliance cord to coffee maker?) Even better if you can plug it into another circuit.
 
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