How does wattmeter work

In simple words, a wattmeter is used for measuring the watts in the circuit. The internal construction of a wattmeter is such that it consists of two cols. One of the coil is in series and the other is connected in parallel. The coil that is connected in series with the circuit is known as the current coil and the one that is connected in parallel with the circuit is known as the voltage coil.

These coils are named according to the convention because the current of the circuit passes through the current coil and the voltage is dropped across the potential coil, also named as the voltage coil. The needle that is supposed to move on the marked scale to indicate the amount of power is also attached to the potential coil. The reason for this is that the potential coil is allowed to move whereas the current coil is kept fixed. When the current passes through the current coil, it creates an electromagnetic field around the coil.

The strength of this electromagnetic field is directly proportional to the amount of current passing through it. How it Works: Voltage Relay.

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How Electronic Timers Work. What Is Pull in Voltage? A dynamometer wattmeter reads both ac and dc powers Advantages of dynamometer wattmeter: It can be used to measure power in dc as well as ac circuits. It provides accurate readings. As both coils are air-cored it is free from hysteresis and eddy current losses. The scale is uniform Disadvantages of dynamometer wattmeter: As the coils are air-cored, the magnetic fields created are not strong. This requires more turns in moving coil and hence increased power loss.

The torque weight ratio is small. It will be affected by stray magnetic field. At low power factors the inductance of pressure coil introduces serious error. So a compensation is mandatory. It is costlier than an induction instrument of the same ratings. Wattmeter on DC circuits: For d. Simply by multiplying V and I the power can then be calculated.

Wattmeter Reading Errors Types of wattmeters You might have landed in this page since you might have searched how wattmeter works As a special case reactive power can be measured in a 3-ph balanced circuit by using a single wattmeter. A wattmeter can certainly be used to measure power in a DC circuit, provided it is rated for the current and voltage and for direct current many wattmeters contain transformers or induction motors and can only work on AC. Power factor is not an issue in DC power circuits.

Power consumption is measured by calculating it over time, using at least one complete cycle. On average it consumes 30W calculation: 0. Electric power is defined as the electric work done or electric energy dissipated per unit time. It is measured in Joules per second, i. In case of DC circuits, electric power is the product of voltage times the current. The wattmeter is an instrument for measuring the electric active power or the average of the rate of flow of electrical energy in watts of any given circuit.

Electromagnetic wattmeters are used for measurement of utility frequency and audio frequency power; other types are required for radio frequency measurements.

If there is a reactive load inductive or capacitive the power factor is less than 1 which mean there is some power loses.