Cost to Operate Motor

The maximum energy usage this motor will draw is 2.5 amp/hr. This will only happen if the motor is run continuously for an hour. If the motor is run for only a half hour then you will consume 1.25 amp/hr. Now there is a small caveat. Many motors will draw a higher amount of current during their start up. But typically this period of time does not last more than a few seconds and therefore not a significant portion of the cost.

What?

Energy usage is not measured in amp/hr, it is measured in kW-hrs or kVA-hrs.

Multiply the operating voltage of the motor times 2.5 and that will give you the power rating of the motor in VA.

Multiply the VA (or kVA) times the length of time the motor is running in hours and that will give you the energy the motor can consume in units of VA-hrs or kVA-hrs.

Power and energy used during startup will generally be higher.

<...amp/hr...>

Should that be "amp-hr"?

Yes, my technical inaccuracy. The amp/hr rate will only scale with energy if the voltage and the phase angle between voltage and current remain constant. But since most utilities do a very good job of keeping the voltage constant and these same utilities charge people the same regardless of the phase angle, I took the liberty to simplify for the OP.

thanks.

GA. You are the first one to consider the complete costs.

I am appalled by the First 7 answers! Each of them has some truth, but none of them really answers the original question!

Without a photograph of the entire nameplate, no one can be sure of the true meaning of the 2.5 Amps. It could be the nominal current rating of the motor at full load (most likely), but it could also be other values, such as locked rotor current.

The cost of operating the motor (separate from the cost of acquiring and disposing of the motor, as correctly mentioned by JRaef) depends on the current actually used by the motor (as correctly indicated by LynLynch), as well as the voltage and the time of day/night. Industrial electric rates commonly are higher at times of peak consumption and lower at other times.

The simple complete answer is that the cost of operation is the product of the actual average current with the actual average voltage and the time of operation and the electric rate. Current in Amperes * voltage in Volts = power in Watts. Power in Watts * time in hours = energy in Watt-hours. Since electric rates (in the USA) are normally specified in terms of $/kWh, there must be a conversion from W to kW included.

Assuming that this is a single phase 220V motor, a sample calculation could be:

Cost/day = (2.0A * 220V * 8hr/day)/1000 W/kW * 0.12$/kWh = (3520 Whr/day) /1000 W/kW * 0.12$/kWh= 3.52 kWhr/day * 0.12$/kWh= $0.42/day.

If it is a three-phase motor, it becomes significantly more complex...

Hi

Your motor taking current is 2.5Amps

If motor Voltage is 250v

HP is = I*V*Pf*Eff/746

= 2.5*250*0.9*0.85/746

= 0.75 HP

= 0.55 KW

if motor running for one hour the unit willbe 0.55KW/Hr

If motor Voltage is 440v

HP is = I*V*1.732*Pf*Eff/746

= 2.5*440*1.732*0.9*0.85/746

= 2HP

= 1.5KW

if motor running for one hour the unit willbe 1.5KW/Hr

Now u can calculate Hourly consumption

ALL ANSWERS ARE GOOD AND CONSIDERABLE BUT SOME OTHER FACTORS ARE IMPORTANT IS MOTOR 3PH ORE 1PH ? ENERGY RATE DIFFERS FROM MORNING TIME TO NIGHT. IT'S BETTER TO USE A KWH COUNTER WITH ALL CONSIDERATIONS LIKE MAINTENANCE AND.....

good greif guys.

Many motors and appliances have stickers, tags and even the energy star rating stickers that are way off from the motor or devices actual power use.

For $20, you can buy a device known as a kill-a-watt meter.

you plug this into your wall outlet, then plug your motor or device in operation into the kill-a-watt meter.

Then you look at the guage, or leave it plugged in this way, for 24 hours.

It will tell you the exact amount of electricity your device has used.

Manufacturer ratings of power draw are WAY off sometimes due to your designed usage, area temperature or humidity, motor wear and tear, or actual misrepresentation from the mfg.

The power consumption for a common box fan will fluctuate due to humidity or air temp the fan is moving.

The sticker or tag is just an average to guess by when designing/loading circuits and breakers and wire guage,etc.

Even new cars from the factory do not get the exact same mpg under identical operating conditions.

For instance, I think there is a file up at the yahoo refrigerator alternative group that shows the sticker rated electrical use for many new energy star refrigerators.

The stickers stated usage is way off, up and down, for many of the units, from their actual power usage. Some use almost twice what the sticker says, some use only half.