Types of Electrical Measuring Instruments | Absolute and secondary instruments

Types of Electrical Measuring Instruments: A Comprehensive Guide

Electrical measuring instruments are essential tools used in various industries and applications to quantify and monitor electrical parameters accurately. These instruments enable engineers, technicians, and electricians to measure voltage, current, resistance, power, and other electrical characteristics. Understanding the different types of electrical measuring instruments is crucial for safe and efficient electrical system operation and maintenance. In this article, we will explore some of the most common types of electrical measuring instruments.

1. Voltmeter:

• Function: Measures voltage (potential difference) between two points in an electrical circuit.
• Types: Analog voltmeters, digital voltmeters (DVM), and multimeters with voltage measurement capability.
• Applications: Used for troubleshooting, circuit testing, and monitoring voltage levels in electrical systems.

2. Ammeter:

• Function: Measures electric current in a circuit.
• Types: Analog ammeters and digital ammeters.
• Applications: Essential for monitoring and maintaining current levels within specified limits in various electrical systems.

3. Ohmmeter:

• Function: Measures electrical resistance or impedance.
• Types: Analog ohmmeters and digital ohmmeters.
• Applications: Used to test the integrity of electrical components, identify faulty wiring, and measure resistance in circuits.

4. Wattmeter:

• Function: Measures electrical power in both AC and DC circuits.
• Types: Analog and digital wattmeters.
• Applications: Crucial for determining power consumption, efficiency analysis, and billing in commercial and industrial settings.

5. Power Factor Meter:

• Function: Measures the power factor in AC circuits.
• Types: Analog and digital power factor meters.
• Applications: Helps assess the efficiency of power usage and optimize power factor correction.

6. Frequency Meter:

• Function: Measures the frequency of an AC signal.
• Types: Analog and digital frequency meters.
• Applications: Used in applications where precise frequency control is necessary, such as power generation and distribution systems.

7. Oscilloscope:

• Function: Displays voltage waveforms as a function of time.
• Types: Analog and digital oscilloscopes.
• Applications: Essential for analyzing and troubleshooting complex electrical and electronic systems, including signal characterization and diagnosis of faults.

8. Clamp Meter:

• Function: Measures current by clamping around a conductor without disconnecting the circuit.
• Types: Analog and digital clamp meters.
• Applications: Ideal for measuring current in hard-to-reach or live circuits, such as in HVAC and electrical maintenance.

9. Insulation Resistance Tester:

• Function: Measures the insulation resistance of electrical insulation materials.
• Types: Handheld and benchtop models.
• Applications: Used to assess the insulation quality of wires, cables, and electrical equipment to prevent electrical breakdowns.

10. Earth Ground Tester:

• Function: Measures the resistance of an earth ground electrode or grounding system.
• Types: Stake-type testers, clamp-on testers, and digital testers.
• Applications: Ensures the effectiveness of grounding systems, crucial for safety in electrical installations.

In conclusion, electrical measuring instruments play a vital role in electrical engineering, maintenance, and troubleshooting. Choosing the right instrument for a specific task is essential for accurate measurements and the safe operation of electrical systems. Whether you are a professional electrician, engineer, or simply someone interested in electrical systems, understanding the various types of electrical measuring instruments is a valuable asset.

Electronic measuring  instruments 

In this article, we will discuss only types of electrical measuring instruments. Electrical methods of indicating the output of the detectors are more Rapid than mechanical methods. It is unfortunate that an electrical system normally depends upon a mechanical meter movement as an indicating device. This mechanical movement has some inertia and therefore these instruments have a limited-time response.

The various electrical instruments may, in a very broad sense, be divided into (i) Absolute Instruments and (ii) Secondary Instruments.

Absolute and secondary instruments

Absolute Instruments

are those which give the value of the quantity to be measured, in terms of the constants of the instrument and their deflection only. No previous calibration or comparison is necessary in their case. An example of such an instrument is a tangent galvanometer, which gives the value of current, in terms of the tangent of deflection produced by the current, the radius and number of turns of wire used, and the horizontal component of the earth’s field. 

Secondary Instruments 

are those, in which the value of electrical quantity to be measured can be determined from the deflection of the instruments, only when they have been pre-calibrated by comparison with an absolute instrument. Without calibration, the deflection of such instruments is meaningless. It is the secondary instruments, that are most generally used in everyday work; the use of the absolute instruments being merely confined within laboratories, as standardizing instruments.

What is the difference between absolute and secondary instruments?

The differences between absolute and secondary instruments are tabulated below.