# What is an AC Power Measurement Meter and Its Working

In our day-to-day life, we consume electrical energy for various purposes such as for powering electrical appliances, gadgets, devices, machines, and so on. So, it is essential to measure the amount of power consumed to generate electricity bills which are usually done by energy meters. In general, AC power is measured using various techniques, here in this article let us discuss AC power measurement meter using PIC microcontroller.

## What is AC Power Measurement?

The electrical power can be AC power or DC power, energy meter is used for measuring power. There are various types of energy meters, which are classified as digital energy meter, electronic energy meter, wattmeter, three-phase energy meter, single-phase energy meter, AC power measurement meter, and so on.

The AC power is given by the product of RMS voltage value across the load, RMS current across the load, and power factor of the load. This can be represented as shown in the equation below. Now, AC power measurement can be defined as the measurement of voltage, measurement of current, and measurement of power factor. So, to measure power consumption using PIC microcontroller, it is essential to measure voltage using PIC microcontroller, measure current using PIC microcontroller, and measure power factor using PIC microcontroller.

### AC Voltage Measurement using PIC Microcontroller

The microcontrollers generally operated and manufactured to work with voltage ratings less than or equal to 5V. So, it is not possible to directly measure AC voltage greater than 230V by giving high input voltages to microcontrollers which may cause temporary or permanent damage to microcontrollers.

Hence, it is required to step down the high AC voltage around 230V to 5V for measuring voltage using microcontrollers. The AC voltage measurement using a PIC microcontroller can be done using a difference amplifier or potential transformer. The difference amplifier or potential transformer is used to step-down the voltage and then by using an analog to digital converter or rectifier, the voltage reading is displayed on the LCD display.

### AC Current Measurement using PIC Microcontroller

The PIC microcontroller can be used for measuring AC current with the help of difference amplifier, shunt resistor, and analog to digital converter. Shunt resistors are used as transducers for converting current into voltage as microcontrollers directly can not read current. Thus, the voltage across the shunt resistor can be measured using PIC microcontroller which is again converted into current using Ohm’s law. Thus, the measured AC current is displayed on the LCD display.

### Power Factor Measurement using PIC Microcontroller

The inductor & capacitor cause lagging & leading power factor, the current lags voltage by some angle & current leads voltage by some angle respectively. Thus, the power factor can be defined as the cosine of the angle between current and voltage and is given as To measure the power factor using a PIC microcontroller, the time difference between the voltage and current is determined using zero-crossing detection with the help of a microcontroller external interrupt pin. The interrupt is generated by whenever the voltage waveform’s zero crossings is detected and the internal timer of the microcontroller is used for measuring time. Similarly, whenever the current waveform interrupt is generated, then the timer stops counting and thus time difference is calculated.

This process repeated for a number of times (say 20 to 30) and the average value is taken for better results. Hence, the time difference is used to determine the phase angle difference between voltage and current. Thus, the power factor can be calculated using a PIC microcontroller.

Now, by substituting the values of voltage, current, power factor in the above power equation we can measure AC power. The meter used for measuring power factor can be called as power factor meter.

#### Solar Energy Measurement System Conveyed over RF using a PIC Microcontroller

The main aim of this project is solar energy measurement using multiple sensor data acquisitions. The project utilizes a solar panel that changes its direction according to sunlight. The solar panel parameters such as the intensity of light, temperature, voltage, and current are monitored and also sent to PC using RF.

The project block diagram shown in the above figure consists of various blocks, including solar panel, temperature sensor, light sensor, voltage sensor and current sensor interfaced with the PIC microcontroller. The sensors are used for measuring temperature, light, voltage, and current and is sent to the PC using RF, the same data is displayed over the LCD display.

The power supply block, RF transceiver, PC, max232, 555 timer, and buzzer blocks are connected as shown in the above block diagram. The solar energy measurement can be achieved by measuring factors such as temperature and light intensity that affect energy generation.

There are various types of meters that include power factor meter, digital energy meter, electronic energy meter, three-phase power measurement, energy meter reading over the internet, prepaid energy meter with GSM interface, programmable energy meter for electrical load survey.

Are you interested in designing electronics projects using the PIC microcontroller? Then, post your queries or ideas in the comments section below for technical help regarding project solutions.