Three Phase Wattmeter
Table of Contents
To gauge the power of a three phase circuit, a three-phase wattmeter is employed. Three phase Wattmeter combine the two separate Wattmeters into a single assembly. The spindle that holds their moving coils is the same. Two components comprise the Three-Phase Wattmeter. The pressure coil and current coil are combined to form the single element. While the pressure coils are the moving coil of the Wattmeter, the current coils are thought of as the fixed coil.
Working Principle of Three Phase Wattmeter
It operates on the tenet that when a conductor carrying current is placed in a magnetic field, a torque develops on the conductor. When the measuring power goes through the rotating coils, the coil develops torque. The torque is a kind of mechanical force that has the ability to cause an object to be deflected in a circular motion. The torque grows on both elements in a three-phase Wattmeter. Each element’s torque value is inversely correlated with the amount of power passing through it. The torque on each individual Wattmeter is added together to create the three-phase Wattmeter’s overall torque.
Let’s use mathematical expressions to better understand this.
Take into account that the power that flows through that element is P1, and the deflecting torque that develops on coil one is D1. Similarly, D2 represents the torque that develops on coil 2 and P2 represents the power that travels through coil 2.
The total amount of torque that the coil generates is expressed as
Connections of three-phase Wattmeter
Consider the two Wattmeters in the circuit. Both Wattmeters’ current coils are connected across any two phases, such as R and Y. Both Wattmeters’ pressure coils are connected across the third phase, designated by the letter B. So The accuracy of the Three-Phase Wattmeter’s components will be impacted by mutual interference. The phenomenon in which the fields of two elements interact with one another is known as mutual interference. The laminated iron shield is positioned between the components in a three-phase Wattmeter. The iron shield lessens the elements’ mutual effect.
The Weston method can be used to offset the mutual effect. The Weston method makes use of movable resistors. So This resistor corrects the mutual interference that develops between the three phase wattmeter’s components.