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The motor analysis tool is used to calculate an operating motor’s power input, energy consumption, and mechanical power output from the information on the motor's nameplate and live reading data, which is measured while the motor is operating.

The tool is best used when a live reading has been obtained of the motor at a moment in time that accurately reflects its average loading.

To start off, enter a description of the motor for identification.

Specifying where the motor is located can also help differentiate it from other motors at the same facility.

The first section we will start entering in data that we’ve collected is under motor nameplate data.

For motor power supply type, we will usually select three-phase AC power. This is the type of electrical power that is being fed into the motor, and industrial facilities usually run three-phase AC induction motors. You can also select single-phase AC or DC if needed.

For motor enclosure type, motors will either come as totally enclosed fan cooled or open drip proof. Usually you will see these as TEFC or ODP, respectively. This is used to determine the efficiency characteristics of the motor if the rated full-load efficiency of the motor cannot be found on its nameplate.

For drive type, this is the way the motor transfers its mechanical power to the process. A motor that has a direct drive will transmit pretty much 100% of its mechanical power. Any motor that is connected with any sort of belt drive will lose some of that mechanical power to belt friction, therefore reducing the overall system efficiency.

For the rest of the parameters that start with the word ‘rated’, these are values that can be obtained from the nameplate data that was collected from the motor. These rated values give us a general overview of how the motor should behave, but does not tell us anything about how much power is being consumed.

The rated horsepower gives us a general overview of how much power the motor can deliver.

The rated voltage is the voltage that the motor is designed to run on, and is usually 460 or 480 V at most industrial facilities.

The rated full load amperage is the current that the motor will draw at its full load operating point. A motor operates at its full load when it produces its rated horsepower.

The rated full load speed is the speed that the motor will run at full load, and is usually 3600, 1800, or 1200 RPM.

The rated full load efficiency is the input to output efficiency of the motor when running at full load.

The rated full load power factor is the power factor the motor exhibits at full load.

Again, these values do not tell us anything about how much power is being consumed, but gives us an overview on what the motor was designed to do.

Let’s say you couldn’t find the rated full load efficiency or rated full load power factor. The tool provides two sheets that have charts to estimate those missing values. These sheets are based on previously measured motors and may or may not accurately estimate your motor’s efficiency and power factor, so using these values will likely reduce the accuracy of the calculations.

To find an estimated full load efficiency value, go to the efficiency sheet and find the value associated with the motor’s enclosure type, rated full load speed, and rated horsepower. Take this value and enter it into the tool.

To find an estimated full load power factor, go to the power factor sheet and find the value associated with the motor’s rated full load speed and rated horsepower. Take this value and enter it into the tool.

With all the nameplate data entered, let’s move onto the measured data section. If we can obtain a live reading of the motor, this is the most accurate way of determining the power input/output and energy consumption of the motor. With a power quality analyzer, two values will be recorded from the reading: the RMS voltage and the RMS amperage. Entering these values into the tool will give us the most accurate representation of the motor’s operation, because it lets us know what the actual voltage supplied to the motor is and at what load is the motor running at.

Under operational data, these two parameters determine the motor’s energy consumption. Total operation hours will be the number of hours the motor runs in a year.

Load factor is used to find how much the motor is loaded if a live reading is not possible. This parameter is used when the load of the motor can only be estimated from anecdotal information from the facility or other sources. This parameter will be overridden if live reading values are entered. In this case rather than leaving the parameter blank, find the actual load factor by dividing the actual power input by the rated full load power input.

Finally, once all the necessary data is entered into the tool, we will see the resulting values for electrical power input, electrical energy consumption, and mechanical power output of the motor. Note that the mechanical power output of the motor is the power after losses from the drive, so not the power at the shaft of the motor.