Types of Meters

Introduction

Meters play a crucial role in electronic measurements and instrumentation. They are used to accurately measure various electrical quantities such as current, voltage, and power. In this topic, we will explore the different types of meters and their applications in electronic measurements.

DC Meters

DC Ammeter

A DC ammeter is used to measure the flow of direct current (DC) in a circuit. It is connected in series with the circuit under test and measures the current passing through it. There are two main types of DC ammeters:

1. Chopper Type DC Ammeter

The chopper type DC ammeter uses a chopper circuit to convert the DC current into a pulsating DC current. This pulsating current is then measured using a suitable measuring instrument. The chopper circuit helps in achieving high accuracy and stability in current measurement.

1. Solid-State DC Ammeter

The solid-state DC ammeter uses solid-state components such as transistors and operational amplifiers to measure the DC current. It offers high accuracy, fast response time, and low power consumption.

DC Voltmeter

A DC voltmeter is used to measure the voltage across a circuit or component. It is connected in parallel with the circuit under test and measures the voltage difference between its terminals. There are different types of DC voltmeters:

1. Rectifier Type DC Voltmeter

The rectifier type DC voltmeter uses a rectifier circuit to convert the AC voltage into a pulsating DC voltage. This pulsating voltage is then measured using a suitable measuring instrument. The rectifier circuit helps in achieving high accuracy and stability in voltage measurement.

1. Average Responding DC Voltmeter

The average responding DC voltmeter measures the average value of the rectified DC voltage. It is suitable for measuring steady DC voltages.

1. RMS Responding DC Voltmeter

The RMS responding DC voltmeter measures the root mean square (RMS) value of the rectified DC voltage. It is suitable for measuring both steady and varying DC voltages.

1. Peak Responding DC Voltmeter

The peak responding DC voltmeter measures the peak value of the rectified DC voltage. It is suitable for measuring peak voltages or transient voltages.

AC Meters

AC Ammeter

An AC ammeter is used to measure the flow of alternating current (AC) in a circuit. It is connected in series with the circuit under test and measures the current passing through it. There are different types of AC ammeters:

1. Moving Coil AC Ammeter

The moving coil AC ammeter uses a moving coil mechanism to measure the AC current. The coil is placed in a magnetic field and experiences a torque proportional to the current flowing through it. This torque causes the coil to move, and the deflection is proportional to the current.

1. Moving Iron AC Ammeter

The moving iron AC ammeter uses a moving iron mechanism to measure the AC current. The iron piece is attracted towards the magnetic field generated by the current flowing through it. The deflection of the iron piece is proportional to the current.

AC Voltmeter

An AC voltmeter is used to measure the voltage across a circuit or component. It is connected in parallel with the circuit under test and measures the voltage difference between its terminals. There are different types of AC voltmeters:

1. Moving Coil AC Voltmeter

The moving coil AC voltmeter uses a moving coil mechanism to measure the AC voltage. The coil is placed in a magnetic field and experiences a torque proportional to the voltage difference across it. This torque causes the coil to move, and the deflection is proportional to the voltage.

1. Moving Iron AC Voltmeter

The moving iron AC voltmeter uses a moving iron mechanism to measure the AC voltage. The iron piece is attracted towards the magnetic field generated by the voltage difference across it. The deflection of the iron piece is proportional to the voltage.

Multi-meters

A multi-meter, also known as a universal meter, is a versatile instrument that combines the functionalities of multiple meters into a single device. It can measure various electrical quantities such as current, voltage, resistance, and continuity. There are two main types of multi-meters:

1. Analog Multi-meter

An analog multi-meter uses a needle or pointer to indicate the measured quantity on a scale. It is based on the principle of moving coil or moving iron mechanisms. Analog multi-meters are simple to use and provide continuous measurement readings.

1. Digital Multi-meter

A digital multi-meter uses a digital display to indicate the measured quantity. It converts the analog electrical signals into digital form using an analog-to-digital converter (ADC). Digital multi-meters provide accurate measurement readings and additional features such as data logging and auto-ranging.

Power Meters

A power meter is used to measure the electrical power consumed or generated by a circuit or device. It combines the functionalities of a voltmeter and an ammeter to measure both voltage and current simultaneously. There are different types of power meters:

1. Bolometer

A bolometer is a type of power meter that measures the power by detecting the change in resistance of a temperature-sensitive element. The power dissipated in the element causes a change in its resistance, which is then measured.

1. Calorimeter

A calorimeter is a type of power meter that measures the power by measuring the heat generated or absorbed by a circuit or device. The heat is measured using a temperature-sensitive element, such as a thermocouple or a resistance thermometer.

Real-world Applications and Examples

Meters are widely used in various electronic measurement scenarios. Some examples of their applications include:

• Power generation: Meters are used to measure the power output of generators and turbines in power plants.
• Telecommunications: Meters are used to measure the signal strength and quality in communication systems.
• Electronics manufacturing: Meters are used to test and calibrate electronic components and devices during the manufacturing process.

Accurate measurements are essential in these industries to ensure the proper functioning and performance of electrical systems and devices.

Conclusion

Meters are fundamental instruments in electronic measurements and instrumentation. They play a crucial role in accurately measuring various electrical quantities. In this topic, we explored the different types of meters, including DC ammeters, DC voltmeters, AC ammeters, AC voltmeters, multi-meters, and power meters. We also discussed their operation principles, advantages, and disadvantages. Understanding the different types of meters and their applications is essential for anyone working in the field of electronic measurements and instrumentation.

Summary

Meters play a crucial role in electronic measurements and instrumentation. They are used to accurately measure various electrical quantities such as current, voltage, and power. In this topic, we explored the different types of meters, including DC ammeters, DC voltmeters, AC ammeters, AC voltmeters, multi-meters, and power meters. We discussed their operation principles, advantages, and disadvantages. Understanding the different types of meters and their applications is essential for anyone working in the field of electronic measurements and instrumentation.

Analogy

Imagine you are a chef in a restaurant. To prepare a delicious dish, you need to measure the ingredients accurately. Just like meters in electronic measurements, measuring cups and scales help you measure the right quantities of ingredients. Different types of meters, such as DC ammeters, DC voltmeters, AC ammeters, AC voltmeters, multi-meters, and power meters, are like different measuring tools in your kitchen. Each meter has its own purpose and measurement principles, just like each measuring tool in your kitchen serves a specific purpose.