The current passing in the conductor has a certain electromotive force. When it becomes necessary to determine its value on a separately selected section of the circuit, a voltage meter is used. The unit of measurement is considered to be a volt, and the device is called a voltmeter. This apparatus is widely used in industry, research and everyday life.
Content
- Classification and principle of operation
-
Types of voltage meters
- Connection and specifications
Classification and principle of operation
To better understand what kind of device is used to measure voltage and why it is called that, it is worth turning to physics. By definition, it is a force that acts on electrons and makes them move in one or different directions. The unit of measurement is volts.
Voltmeters are used by people in various fields of activity. There are many varieties and modifications of this device. Depending on design features and field of application, devices for measuring electrical voltage are classified according to three main parameters:
- Operating principle. Electromechanical and electronic.
- Appointment. DC and AC, pulse and phase-sensitive, as well as selective and universal.
- Design and application. Stationary, portable and panel board.
The principle of operation of electromechanical voltmeters is based on a change in the magnetic field. The current flows through the winding, which creates an electromagnetic field. As a result of this, the arrow, mounted on the axle with a permanent magnet, deflects and shows the value of the electromotive force (EMF).
Electronic devices can also have an arrow. The housing contains an AC-to-DC converter, and the pointer deflection occurs under the action of a voltage detector.
Digital meters display information on a liquid crystal display. Their work is based on a microcircuit and a signal converter.
Types of voltage meters
A voltmeter for measuring voltage in a DC circuit is marked B2. It is used as a tester for wiring and electrical appliances.
If you have to deal with alternating current, the device is marked B3. It has a compact rectifier and signal amplifier.
Pulse (B4) is designed to measure disturbances in the mains. Allows you to find a place in the chain with a weak contact.
Phase (B5) determines the quadrature components of the first harmonic. It is not used in everyday life due to its lack of demand.
Selective (B6) is large and resembles a radio receiver. It can distinguish the frequency of the signal.
The universal voltmeter (V7) is a device for measuring voltage in any type of electrical network.
Portable models (tester, multimeter) are small stand-alone devices equipped with electrodes.
Stationary voltmeters are large and heavy instruments, often built into equipment. Used in production to control the operation of the electrical system.
Shield devices are more simple. They are integrated into household electrical appliancesand also used on vehicles as sensors.
Connection and specifications
To make an adequate measurement, the voltmeter must be connected to the required section of the circuit through a serial connection. Portable meters are connected using electrodes or special clothespins. When taking readings from a power source, the electrodes are connected directly to the terminals.
Before connecting, it is worth defining:
- order of magnitude of voltage;
- polarity;
- the nature and type of current;
- measurement mode (on a universal voltmeter).
Before you buy or start using a voltmeter, it is useful to evaluate its effectiveness. You need to determine your needs and choose the required voltage meter.
Technical indicators are assessed according to the following parameters:
-
Internal resistance. The higher this indicator, the more accurately it measures voltage. - Range. As a rule, devices are supplied with a universal range, which is enough for any ordinary consumer. However, for scientific and highly specialized purposes, devices designed to accurately measure very small quantities may be needed. In production, you have to deal with a voltage of hundreds of kilowatts, which also requires highly specialized voltmeters.
- The error of indicators.
- AC frequency range.
Having dealt with the question of what device the voltage is measured with, it is worth recalling the safety measures. Electric current can seriously injure and even kill a person. If high voltage readings are being taken, do not touch the wires with bare parts of the body. Wear protective gloves on your hands.
