Classification of Electrical Measuring Instruments [Complete Guide]

This is the second article based on the electrical instruments- classification of electrical measuring instruments.

Before this article, I shared an electrical measuring Instrument covering all different instruments and their uses.

The main functions of the measuring instrument are indicating, recording, detecting, controlling, and testing the electrical units. These instruments are available in analog or digital form.

Mostly, analog meters are used in the electrical laboratory for practical studies. And digital meters are mostly used for commercial, industrial, and various other purposes.

Let’s study, what are the different types of electrical measuring instruments.

Classification of Electrical Measuring Instruments

On the basis of the electrical and electronic study, measuring instruments are classified into different categories with different perspectives.

I am describing each classified electrical measuring instrument, by one-by-one.

Classification according to the Electrical Quantity

As per the Electrical Quantities, instruments are broadly classified into two parts.

1. Absolute Instrument
2. Secondary Instrument

Explanation as,

1. Absolute Instrument

This instrument gives the value of the electrical quantity to measure in terms of the constant and its deflection. This instrument is known as ‘Absolute Instrument’.

It is also called a Primary Instrument or Indirect Instrument. These instruments are not required to compare with the standard values.

Example: Tangent Galvanometer is the best example of an absolute instrument. It is used for detecting and displaying an electric current unit.

These types of instruments are rarely used for commercial purposes.

2. Secondary Instrument

The instrument gives the value of the quantity to be measured directly into the deflection. This instrument is known as ‘Secondary Instrument’.

It is also called as Direct Instruments.

These instrument values are required to compare with absolute instruments or the standard values of the instruments.

The secondary instrument is classified into two-part,

• Deflection Instrument
• Null Deflection Instrument

Example: Ammeter, Voltmeter, Wattmeter, etc are examples of secondary instruments.

Classification according to the Nature of the Operation

The instrument can also be classified based on the nature of the operation. They majorly fall into the secondary instrument.

This instrument is divided into four major parts.

1. Indicating Instrument
2. Recording Instrument
3. Integrating Instrument
4. Null Deflection instrument

Shortly describe as,

1. Indicating Instrument

The Indicating Instrument displays only the value of the electrical quantities per time of measurement.

This instrument gives the reading only when connected to the electrical supply. Otherwise, it goes to the zero position.

Example: Ammeters, Voltmeters, Wattmeters, etc are examples of the indicating instrument.

2. Recording Instrument

The Recording Instrument displays and records the reading of the electrical quantities at per time of measurement.

This instrument is generally used in the Generating Station and Substation.

Example: ECG, and X-Rays are examples of recording instruments.

3. Integrating Instrument

The Integrating Instrument displays, record, and add the numerical value of the reading of the electrical quantities per time of measurement.

Example: Energy meter, and Ampere-hour meter are examples of the integrating instrument.

4. Null Deflection Instrument

The Null Deflection Instrument shows the reading of the electrical quantities without the deflection angle at per time of measurement.

Example: The potentiometer is an example of a null deflection instrument.

Classification according to the Electrical Supply

This classification is based on the alternating current (AC) and direct current (DC)types of an electrical sources.

1. AC Instrument
2. DC Instrument

1. AC Instrument

The AC Instrument is connected to the AC supply. Further, they are classified into two parts…

• Single Phase AC Instrument
• Three Phase AC Instrument

Example: Moving Instrument [M.I.], Induction Instrument, Electrostatic Instrument, dynamometer Instrument, and Electrostatic Instrument are examples of the AC Instruments.

2. DC Instrument

The instrument is connected with the DC supply.

Example: ‘Permanent Magnet Moving Coil Instruments’ is the best example of the DC instrument.

Classification according to the Effect

Due to the various magnetic effects, electromagnetic induction effects, electrostatic effects, thermal effects, chemical effects, etc., there are more chances to get the application or system damaged.

So, multiple types of instruments are used to measure and compare unknown quantities with the standard value. These instruments protect the device.

The classification is as follows.

1. Moving Coil Instruments
2. Moving Iron Instruments
3. Induction Instruments
4. Electrostatic Instruments
5. Electrolytic Instruments
6. Hot Wire Instruments

Classification according to Moving Coil [M.C.]  Instrument

The Moving Coil Instrument is classified into two parts.

1. Permanent Magnet Moving Coil [PMMC] instrument
2. Electrodynamic or Dynamometer types instrument

Classification according to Moving Iron [M.I.] Instrument

The Moving Iron Instrument is classified into two parts.

1. Attraction type M.I. instrument
2. Repulsion type M.I. instrument

Classification according to an Electrical Application

In daily routine, multiple instruments are used for multiple purposes. Instruments work on AC or DC electrical sources as per the appliance’s use.

Here is the list of the most popular and widely used instruments.

1. Ammeter
2. Voltmeter
3. Ohmmeter
4. Multimeter
5. Wattmeter
6. Fluxmeter
7. LCR meter
8. Oscilloscope
9. Vectorscope
10. Synchroscope
11. Galvanometer
12. Energymeter
13. Tachometer
14. Speedometer
15. Frequency meter
16. Capacitance meter
17. Power factor meter
18. Ampere-hour meter
19. Live leakage detector
20. Earth leakage detector
21. Phase sequence detector
22. Insulation fault-detecting instrument
23. Megger, etc.

These instruments are used for commercial, industrial, practical, and many more purposes. They are manufactured by the topmost electrical companies.

There is also one more type of instrument called a multimeter.

What is a Multimeter?

A multimeter is a popular type of electrical measuring instrument. Like its name, it works like an ammeter, voltmeter, and ohmmeter to measure current, voltage, and resistance respectively.

The multimeter is available in two different forms, like-

1. Analog type Multimeter
2. Digital type Multimeter

In this advanced technology, both types of meters are needful as per requirement.

What are the advantages of a digital multimeter over an analog multimeter?

The analog type of multimeter shows the continuous signal. It detects and displays the electrical reading by using the moving pointer.

Whereas, the digital type of multimeter shows the discrete signal. And it measures and displays the numeric measuring unit or value.

So, a digital multimeter (DMM) gives a more accurate, fast response, and readable digital output over an analog multimeter.

A digital meter is also called as ‘Smart Meter ‘ or ‘Advance Meter’.

With this single smart meter, you can measure multiple units. Instead of buying separate meters to measure current, voltage, resistance, and so on, you buy digital a multimeter.

Similarly, the LCR meter is a type of multimeter that measures the inductance (L), capacitance (C), and resistance (R).

From this study, we conclude that measurements and instruments are the most essential term in electrical, electronics, mechanical, and other related fields.

These types of instruments in instrumentation work as protective devices and are helpful for building electrical and electronic projects.

That’s all about types of measuring instruments in electrical and mechanical.

Read more related Articles:

• Analog signal vs Digital signal
• Analog multimeter vs Digital multimeter
• Voltmeter vs Potentiometer
• Ammeter vs Voltmeter
• Pros & Cons of digital multimeter
• Digital pulse oximeter
• Different types of Sensors

If you have any queries or points to discuss regarding different types of measuring instruments, write in the comment.

Thanks for Reading!

Dipali Chaudhari

I have completed master in Electrical Power System. I work and write technical tutorials on the PLC, MATLAB programming, and Electrical on DipsLab.com portal.

Sharing my knowledge on this blog makes me happy.  And sometimes I delve in Python programming.