Voltmeter, principle, types, applications

Voltmeter definition:

A voltmeter is a device that calculates the voltage, or electrical potential difference, between two points in an electrical circuit.

Working/Principle:

The working principle of a voltmeter is based on measuring the voltage using a known resistance and applying Ohm's law.

The basic principle:
A voltmeter is connected in parallel with the component or circuit whose voltage is being measured. It has a high resistance, usually on the order of one megaohm (MΩ) or higher. This high resistance causes the current flowing through the voltmeter to be negligible compared to the current flowing through the circuit being measured. As a result, the voltmeter does not significantly affect the performance or accuracy of the circuit.

Ohm's law:

According to Ohm's law, a component or circuit's voltage (V) is equal to its current (I) flow times its resistance (R), which is expressed as a multiplication factor. Mathematically, this can be expressed as follows:

V = I * R

A voltmeter uses this principle to measure voltage.

Measuring procedure:

When a voltmeter is connected in parallel to a component or circuit, the voltage at its terminals can be equal to the voltage across the component or circuit being measured. Since the resistance of the voltmeter is known and constant, the current flowing through the voltmeter can be determined using Ohm's law.
By measuring the current flowing through a voltmeter, the voltage can be calculated using the formula V = I * R. The display or scale of the voltmeter shows the value of the voltage based on the current flowing through it and the known resistance.

It is important to select the correct voltage range on your voltmeter to ensure accurate readings. Different voltmeters can have multiple voltage ranges to accommodate a wide variety of voltage levels.

Thus, the working principle of a voltmeter involves connecting it in parallel to the component or circuit being measured, using the well-known high resistance, and applying Ohm's law to calculate the voltage based on the current flowing through the voltmeter flows.

Types of voltmetr:

There are roughly two types of voltmeters: analog voltmeters and digital voltmeters. Each type has its own characteristics and applications.

1)Analog voltmeters:
Analog voltmeters use mechanical mechanisms and a moving pointer to indicate the voltage level. They usually have a scale on which an arrow moves to indicate the voltage measurement. Analog voltmeters are based on the principle of electromagnetic induction.

There are two common types of analog voltmeters:

Moving Coil Voltmeter (MCV):

MCVs use a coil of wire suspended in a magnetic field. As current flows through the coil, it experiences torque and rotates. The rotation of the coil is proportional to the measured voltage and this movement is mechanically linked to the arrow indicating the voltage value on the scale.

Moving Iron Voltmeter (MIV):

The MIV uses a piece of moving iron that is attracted to a stationary coil that carries the current to be measured. The force of attraction between the moving piece of iron and the coil is proportional to the measured voltage and this force is converted into a mechanical movement that moves the pointer on the scale.

Analog voltmeters are known for their smooth needle movement and ease of interpreting trends or fluctuations. However, they usually have lower accuracy and limited resolution than digital voltmeters.

2)Digital voltmeters:

Digital voltmeters convert analog voltage into a digital representation for display. They provide a digital readout of the voltage value, making them easy to read and interpret. Digital voltmeters are based on digital circuitry and often include an analog-to-digital converter (ADC) to convert an analog voltage to a digital signal.
There are two common types of digital voltmeters:

Linear type digital voltmeter (R-DVM):

R-DVMs measure the time it takes for a voltage ramp to reach the measured voltage. This measurement time is then converted into a digital value and displayed. R-DVMs are relatively simple and inexpensive, but may have limited accuracy and speed.

Integrator-Type Digital Voltmeter (I-DVM):

I-DVMs integrate the voltage measured over a fixed period of time using an integrating capacitor. The integrated value is then converted to a digital value and displayed. I-DVMs generally offer higher accuracy and better resolution than R-DVMs, but can be more complex and expensive.

Digital voltmeters have advantages such as greater accuracy, a larger measuring range and additional functions such as the possibility of autorange and data logging.

In general, both analog and digital voltmeters have their advantages and are used in different applications depending on the accuracy required, the measurement range and the specific needs of the measurement task.

Applications:

Voltmeters are widely used in various applications for measuring and monitoring voltage levels. Here are some common uses for voltmeters:

Circuit Testing and Troubleshooting:

Voltmeters are essential tools for testing and troubleshooting electrical circuits. They help identify power surges, bad connections, and other electrical problems. By measuring the voltage at various points in a circuit, technicians can locate and diagnose problems.

Power Systems:

Voltmeters are used to measure and monitor voltage levels in power systems. They are critical for maintaining desired voltage levels, ensuring proper operation of electrical equipment and preventing damage to sensitive devices. Voltmeters are used in power distribution systems, substations and switchboards.

Electronics and electrical engineering:

In electronic circuits, voltmeters are used to measure voltage across components such as resistors, capacitors, and integrated circuits. They help engineers and technicians analyze circuit behavior, verify circuit performance, and ensure components operate within specified voltage ranges.

Battery Test:

Voltmeters are used to measure the voltage of batteries. They help determine the state of charge and evaluate the condition of batteries in a variety of applications, such as automotive, marine and renewable energy.

Quality control and calibration:

Voltmeters are used in manufacturing and quality control processes to ensure the accuracy and reliability of electrical equipment. They are calibrated and used as reference instruments to verify the operation of other voltmeters and electrical measuring equipment.

Research and Development:

Voltmeters are widely used in research and development related to electrical measurements. They help scientists and researchers analyze voltage fluctuations, study electrical phenomena and characterize electrical systems.

Education and Training:

Voltmeters are the most important tools in the teaching and learning of electrical engineering. They are used in laboratories and educational institutions to teach students about the principles of voltage measurement, electrical circuits, and troubleshooting techniques.

In general, voltmeters play a vital role in various industries, including electronics, power systems, manufacturing, research, and education. They provide important information about voltage levels, ensure accurate measurements, efficient troubleshooting and efficient maintenance of electrical systems and devices.