# What is Unit of power, Watt, kWh and kVAh

Power is basic necessity and life can not be imagined without power. As power is essential part of our life, we use power to run our machines like Television, Refrigerator, Fans, Air conditioners, Lights, Geyser, mixture grinder and list goes on and on. For using power we need to pay electricity bill, for household application electricity is generally billed on monthly basis. At a specific day of every month someone from electricity department visit out home and takes reading and share bill of the month. In the electricity bill it is mentioned that cercent unit of power is consumed for the month and for that certain unit of power billing is done. For many people power and electricity seems to be same and are unable to differentiate between power and electricity. Let us understand both in very simple language.

### What is Electricity and Power

Electricity is the presence and flow of electric charge, eg electrical energy flows from one place to another in the form of electron though copper wire, With the use of electricity we can transmit electrical energy from one place to another place to perform necessary work. Electricity are sometimes also referred as electrical energy but it is not true as electricity is the transmission medium for electrical energy not energy itself.

Power is the measurement of electrical energy. and it is the amount of energy transferred per unit of time. Power is measured in Watt and watt is joule per second. It has both energy and time units for measurement. Therefore

Power = Energy / Time Ie Power = Joule / Sec ; Power = Watt

### Unit of Power kWh

For Electricity billing for household application kilowatt-hour is commonly used measurement unit, Kilowatt- hour for power consumption means 3600 Kilo Joules of electrical energy.

The running cost of any appliance is calculated by multiplying power consumption of appliance and operating hours of equipment. Eg Suppose We are using Electic heater for 1.5 Kw for 5 Hrs daily it will consume 1.5X 5 = 7kWh of power consumption. Simillarly if it is operated for 30 Days in a month total power consumption of electric heater shall be 7 X 30 = 210kWh, Simillary power consumption of each appliance can be calculated to estimate monthly power consumption. Power cost is multiplied with power consumption to get monthly bill of a house.

### What is kWh and kVAh ?

Power consumption in residential application is measured in kWh, while for industrial application it is measured in kVAh. kVAh is the most prefered unit of power consumption by utility / electricity companies in industries as major load in industrial application is inductive and requires reactive power in addition oto active power requirement. Active power is consumed by the load to perform work like lighting heating or motion. While reactive power is consumed for generation electromagnetic field to run electrical motors. Reactive power consumption for resistive load is NIL as no electromagnetic field is required for its operation.

If power billing is on active energy kWh, cost of supplying reactive power is beared by utility company. In case of power billing on reactive power kVAh user has take burden of maintaining power factor , for detail on power factor click here, kVAh billing is cheaper than kWh billing due to scope of user to maintain power factor, Utilities companies also provides incentive and penalty charges for maintaining power factor as per limit suggested by utilities company.

### How Energy consumption is estimated ?

Energy consumption is estimated based on power consumption of Appliances or electrical equipment. We can easily get detail of power consumption of appliances being used in our house, For fixed load like Tubelight, Water heater etc,Operating hour multiplied by the rated power consumption of appliance shall be estimated energy consumption for the equipment.

For variable load appliances power consumption varies based on electrical load like inverter air conditioner, Refrigerator with inverter compressor. In this type of equipment estimation of power consumption is difficult, Estimation of power in this category of appliances can be done with the historic power consumption pattern.