Measurement and Instrumentation - Induction Type Instruments solve two methods
1 Answer
Induction-type instruments are a type of electrical measuring instrument that work on the principle of electromagnetic induction. They are commonly used to measure AC (alternating current) quantities, and they operate based on the interaction between the magnetic field produced by the current being measured and the magnetic field produced by a coil within the instrument. There are primarily two methods for measuring electrical quantities using induction-type instruments: the Ammeter method and the Voltmeter method.
Ammeter Method:
In this method, an induction-type instrument is used as an ammeter to measure the current flowing through a circuit. The instrument is connected in series with the circuit whose current is to be measured. The current passing through the circuit also passes through the coil of the instrument. The magnetic field generated by the current interacts with the magnetic field of the coil, causing a torque to be exerted on the moving system of the instrument. This torque causes the pointer of the instrument to deflect on a scale, indicating the value of the current.
Voltmeter Method:
In this method, the induction-type instrument is used as a voltmeter to measure the voltage across a component or circuit. The instrument is connected in parallel with the component or circuit whose voltage is to be measured. The coil of the instrument is connected in parallel with a high-value resistor, which is often referred to as a series multiplier or a voltage multiplier. When voltage is applied across the resistor and the coil, a current flows through them. The magnetic field produced by this current interacts with the magnetic field of the coil, causing the moving system of the instrument to deflect. The deflection is proportional to the voltage being measured.
Both methods rely on the principle of electromagnetic induction, where the interaction between magnetic fields generates a force or torque that causes the moving system of the instrument to deflect. The degree of deflection is directly proportional to the electrical quantity being measured (current or voltage). However, it's important to note that induction-type instruments are typically used for measuring AC quantities because they are inherently suited to respond to rapidly changing magnetic fields, which are characteristic of alternating currents. For DC measurements, other types of instruments, such as moving coil or moving iron instruments, are more commonly used due to their better accuracy and performance with direct current.
Ammeter Method:
In this method, an induction-type instrument is used as an ammeter to measure the current flowing through a circuit. The instrument is connected in series with the circuit whose current is to be measured. The current passing through the circuit also passes through the coil of the instrument. The magnetic field generated by the current interacts with the magnetic field of the coil, causing a torque to be exerted on the moving system of the instrument. This torque causes the pointer of the instrument to deflect on a scale, indicating the value of the current.
Voltmeter Method:
In this method, the induction-type instrument is used as a voltmeter to measure the voltage across a component or circuit. The instrument is connected in parallel with the component or circuit whose voltage is to be measured. The coil of the instrument is connected in parallel with a high-value resistor, which is often referred to as a series multiplier or a voltage multiplier. When voltage is applied across the resistor and the coil, a current flows through them. The magnetic field produced by this current interacts with the magnetic field of the coil, causing the moving system of the instrument to deflect. The deflection is proportional to the voltage being measured.
Both methods rely on the principle of electromagnetic induction, where the interaction between magnetic fields generates a force or torque that causes the moving system of the instrument to deflect. The degree of deflection is directly proportional to the electrical quantity being measured (current or voltage). However, it's important to note that induction-type instruments are typically used for measuring AC quantities because they are inherently suited to respond to rapidly changing magnetic fields, which are characteristic of alternating currents. For DC measurements, other types of instruments, such as moving coil or moving iron instruments, are more commonly used due to their better accuracy and performance with direct current.