# fridge serge, I used clamp meter, and...

Registered Users Posts: 5
Hello

I just recieved a 220v 1200Watt Pure Sine wave inverter.

I would like some help learning about serge power.

I used my clamp meter and while compressor is running it is using 0.5A @ 220volt

so that would be 110watts?? it is a large fridge 525 Liter stainless frost free fridge.
I looked close at the compressor it is a 1HP compressor.

can you explain if the fridge is running on low power or something?

Thankyou
Shaun

some other applicnecs I tested

Plasma TV - 0.5-1A @ 220v...
Yamaha HIFI Reciever - 0.1-0.4A upto high volume

• Solar Expert Posts: 5,433 ✭✭✭✭
Re: fridge serge, I used clamp meter, and...

Volts X Amps = Watts

Double the volts/halve the amps=same watts.

So your .5 amps @220v=1[email protected]

Remember starting current (surge) can be as much as 10 times that depending on model and design etc.

110 watts running watts doesn't sound out of the ball park depending on the fridge. A good energy star fridge will burn between .5-1.5 kwh/day.

Tony
Re: fridge serge, I used clamp meter, and...

Welcome to the forum Shaun,
I used my clamp meter and while compressor is running it is using 0.5A @ 220volt

so that would be 110watts?? it is a large fridge 525 Liter stainless frost free fridge.
I looked close at the compressor it is a 1HP compressor.

Sort of...

Watts=Volts*Amps*Power Factor

Power Factor (for motors) is based on the "angle" between the voltage and current. It is sort of like the difference between pulling straight on a rope attached to a car, vs standing off to the side an pulling the rope. Since you are off angle when standing on the side, you have to pull harder to make the car move just a fast vs standing in front and pulling.

Power Factor = 1.0 for resistance heaters and power factor corrected equipment... PF can be as low as 0.5 to 0.6 for motors.

Here is more than you will ever want to know about Power Factor and AC power.

VA=Volt*Amps=Volts*Amps

VA is used to rate Inverters, Transformers and such where the amount of current is important in itself.

To measure the angle you need special equipment to measure both the voltage and current at the same time so that you know the angle, volts, and amperage.

It sounds like you are outside North America--so you cannot use the "Kill-A-Watt" meter that we use (about the best device out there for measuring watts, VA, and PF for the price).

For your location, you may find a Kill-A-Watt meter designed for your electrical system (here is one for the UK).

Most inverters are rated at maximum VA (Volt*Amp) ratings--so your measurement is still valid and useful.

Are you sure about the 1 HP rating? At 110 Watts, that is more like 0.1 or 1/10 HP. Perhaps the HP rating is something else--I would be a bit surprised to see a sealed refrigeration compressor rated in Horse Power.
can you explain if the fridge is running on low power or something?
For a modern family sized refrigerator or freezer, 110 watts to run the motor is probably normal. New energy efficient refrigerators use smaller compressors that run longer vs the older units which had larger compressors that did not run as often.

If this is a frost free / self defrosting design, you will probably find that it some times takes around 500 watts to melt the ice on the evaporator coils.

Somebody here tested running a frost free fridge with the auto defrost heaters disabled and the unit iced up pretty quickly (within a day or so--??? if I remember correctly).

Starting surge for any motor/compressor can demand high current--around 5-10x is not unusual. To accurately measure starting surge currents--you need a special meter (or o'scope) to capture the true value.
some other appliances I tested

Plasma TV - 0.5-1A @ 220v...
Yamaha HIFI Reciever - 0.1-0.4A upto high volume
The big plasma and LCD TV's are frequently not very energy efficient when on. However, they do draw less power when off vs the old picture tube type TVs.

For older stereos (and other devices), the standby power can be quite high. My two year old washer drier are pretty energy efficient (natural gas for drier). Only 250 Watt*Hours per load (0.25 kWhr). However, about 1/2 of the power they use is when they are "off" (electronics still draw 10 watts when turned off).

You may find for some appliances (cable box, DVR's, etc.) that you can save significant power by putting them on their own power switch so you can turn them off (really off) when not being used.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Registered Users Posts: 5
Re: fridge serge, I used clamp meter, and...

UPDATE...

I am stupid.. hahah i read wrong.. it was 1 PH! not 1HP!

1 phase!
I read the sticker ont he back, it says 190 MAX watts
so i think the coils are around the fridge and tthat melts the ice!
because the fridge is about 2 inches from inside to outside walls! either coils ro insulation!

I understand that about PF! same with switching PSW have good PF! reduces computers power usage!

so Size of compressor i am saying it is 1/8th - 1/4 HP

sorry for the error!
but can anyone confirm 10x 0.5A for surge power?
• Solar Expert Posts: 10,300 ✭✭✭✭
Re: fridge serge, I used clamp meter, and...

yes, it can get be that high. your refrigerator runs at 190w max, but try putting a 300w sine wave inverter on it and it will most likely not start.
• Solar Expert Posts: 5,433 ✭✭✭✭
Re: fridge serge, I used clamp meter, and...

Could even be higher momentarily.

T
• Solar Expert Posts: 472 ✭✭✭
Re: fridge serge, I used clamp meter, and...

Yep. I have run my fridge off a 1500W inverter. Pulls around 110W while running, and a whopping 1,100W for a few seconds at startup! Nothing like seeing that near-100A draw from my 12V battery bank when it starts...!

And I had forgotten about the heater elements, when during one test-run the compressor came on and ran a short while then stopped and it started drawing around 400W. Much consternation on my part, until I remembered.
• Registered Users Posts: 5
Re: fridge serge, I used clamp meter, and...

thanks for the welcomes!!!
thanks for the replys! you guys rock!

a last question...

My plan is to save electricity based on running Lights/TV/HIFI off of SOLAR!
so the inverter will be roughly
60-100watts for lighting @ night time!
120-220 watts for tv
20-50 watts for hifi

thats a total of 200-270 watts
running on the inverter
If the power blacks out and I use a relay to switch the fridge to INVERTER Wiring system will my inverter shut off or problems?

do you also think running the fridge of a Pure sine wave be any sort of problem? While testing I heard ticking fromt he compressor after shutting down the inverter!
• Solar Expert Posts: 1,399 ✭✭✭✭
Re: fridge serge, I used clamp meter, and...

Many newer (less then two-three years old) have variable speed compressors to improve average energy consumption. This can cause you to measure different run current depending on speed of compressor.

There are only two dominate manufacturers left for home refrig compressors. Both are Korean, one is Samsung, I don't recall the other.
Re: fridge serge, I used clamp meter, and...

Shaun,

Running your appliances from solar--you have to total up your Watt*Hours first (average use per day):

110Watts * 10 Hours = 1,100 Watt*Hours (TV)
50W * 4H = 200 Watt*Hours (Computer)
etc.:
================================
1,300 Watt*Hours of AC voltage per day (just making numbers up)

Then you need to estimate how much power you can receive from solar... The PV Watts website has some international locations too... Try Bangkok Thailand. Assume 1kW of solar panels (minimum PV Watts accepts), 0.52 Derating (system efficiency) for Off-Grid system, and defaults for the rest (fixed mount panels):
"Station Identification"
"City:","Bangkok"
"State:","THA"
"Lat (deg N):", 13.92
"Long (deg W):", 100.60
"Elev (m): ", 12
"Weather Data:","IWEC"

"PV System Specifications"
"DC Rating:"," 1.0 kW"
"DC to AC Derate Factor:"," 0.520"
"AC Rating:"," 0.5 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 13.9"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:","-99.0 baht/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value (baht)"
1, 5.28, 73, "N/A"
2, 5.61, 70, "N/A"
3, 6.09, 83, "N/A"
4, 5.51, 73, "N/A"
5, 4.84, 66, "N/A"
6, 4.81, 64, "N/A"
7, 4.56, 63, "N/A"
8, 4.23, 58, "N/A"
9, 4.63, 62, "N/A"
10, 4.58, 64, "N/A"
11, 5.20, 70, "N/A"
12, 5.23, 73, "N/A"
"Year", 5.04, 819, "N/A",

So, just in "round numbers" you will get around 60 kWhrs per month of electricity from 1kW of solar+batteries+inverter...

Or 60/30=2kWhrs per day; or 2,000 Watt*Hours per day.

Now run your numbers against the amount of solar panels you wish to purchase... (if your solar panels are less than 1,000 watts/1kW, just multiply the above numbers by the amount you want... ie. 460 watts of solar panels would be *0.46 (0.46 kW) the monthly/daily amount based on 1kW of panels.

Pure/True Sine Wave inverters are pretty much the same as utility grade power (assuming reputable mfg. and not a "MSW" Modified Square/Sine Wave inverter which is very hard on motors and transformers). But, you have to have a large enough inverter/battery bank to support your starting surges--which can be quite high.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset