Measurement and Instrumentation - Induction Wattmeters , construction and its working
1 Answer
An induction wattmeter is an electrical instrument used to measure the power (wattage) of an AC circuit. It operates on the principle of electromagnetic induction and is commonly used to measure power in high-voltage and high-current systems. The construction and working of an induction wattmeter can be understood as follows:
Construction:
An induction wattmeter consists of two main parts: the stationary coil assembly and the moving coil assembly.
Stationary Coil Assembly:
The stationary coil assembly is connected in series with the load (the circuit whose power is to be measured).
It typically consists of two coils wound on a common core, referred to as the current coil and the potential coil.
The current coil is connected in series with the load current, while the potential coil is connected across the load voltage.
These coils are wound in such a way that they create magnetic fields proportional to the current and voltage in the circuit.
Moving Coil Assembly:
The moving coil assembly is free to rotate and is mounted on a spindle.
It is located within the magnetic fields produced by the stationary coils.
The moving coil carries a pointer that indicates the measurement on a calibrated scale.
Working:
The working principle of an induction wattmeter is based on the interaction between the magnetic fields generated by the current and potential coils and the magnetic field in which the moving coil is situated. Here's how it works:
Current Coil Action:
The current coil carries the load current and produces a magnetic field proportional to the current passing through it.
This magnetic field interacts with the magnetic field of the potential coil, causing a torque to develop on the moving coil.
The torque on the moving coil is proportional to the product of the current in the current coil and the current in the potential coil.
Potential Coil Action:
The potential coil is connected across the load voltage and generates a magnetic field proportional to the voltage across the load.
The interaction between the magnetic field of the potential coil and the magnetic field of the current coil also contributes to the torque acting on the moving coil.
Total Torque and Measurement:
The combination of the torques produced by the current and potential coils causes the moving coil to rotate.
The rotation of the moving coil is opposed by a controlling spring that maintains the balance.
The angle of rotation of the moving coil is proportional to the power being measured, i.e., the product of current and voltage.
The calibrated scale attached to the moving coil assembly provides readings in watts directly.
In summary, an induction wattmeter measures AC power by utilizing the interaction between the magnetic fields produced by the load current and voltage. The torques generated by these magnetic fields cause a moving coil to rotate, and the angle of rotation corresponds to the power being measured. The instrument provides a direct reading of power consumption on its calibrated scale.
Construction:
An induction wattmeter consists of two main parts: the stationary coil assembly and the moving coil assembly.
Stationary Coil Assembly:
The stationary coil assembly is connected in series with the load (the circuit whose power is to be measured).
It typically consists of two coils wound on a common core, referred to as the current coil and the potential coil.
The current coil is connected in series with the load current, while the potential coil is connected across the load voltage.
These coils are wound in such a way that they create magnetic fields proportional to the current and voltage in the circuit.
Moving Coil Assembly:
The moving coil assembly is free to rotate and is mounted on a spindle.
It is located within the magnetic fields produced by the stationary coils.
The moving coil carries a pointer that indicates the measurement on a calibrated scale.
Working:
The working principle of an induction wattmeter is based on the interaction between the magnetic fields generated by the current and potential coils and the magnetic field in which the moving coil is situated. Here's how it works:
Current Coil Action:
The current coil carries the load current and produces a magnetic field proportional to the current passing through it.
This magnetic field interacts with the magnetic field of the potential coil, causing a torque to develop on the moving coil.
The torque on the moving coil is proportional to the product of the current in the current coil and the current in the potential coil.
Potential Coil Action:
The potential coil is connected across the load voltage and generates a magnetic field proportional to the voltage across the load.
The interaction between the magnetic field of the potential coil and the magnetic field of the current coil also contributes to the torque acting on the moving coil.
Total Torque and Measurement:
The combination of the torques produced by the current and potential coils causes the moving coil to rotate.
The rotation of the moving coil is opposed by a controlling spring that maintains the balance.
The angle of rotation of the moving coil is proportional to the power being measured, i.e., the product of current and voltage.
The calibrated scale attached to the moving coil assembly provides readings in watts directly.
In summary, an induction wattmeter measures AC power by utilizing the interaction between the magnetic fields produced by the load current and voltage. The torques generated by these magnetic fields cause a moving coil to rotate, and the angle of rotation corresponds to the power being measured. The instrument provides a direct reading of power consumption on its calibrated scale.