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What is the symbol for rectifier, what is a rectifier, what does it do, and what does it do

What is the symbol for rectifier, what is a rectifier, what does it do, and what does it do

August 04 , 2023 0

Rectifiers are devices that convert alternating current to direct current and can be used to power devices and detect radio signals. Rectifiers can be made from vacuum tubes, pilot tubes, solid-state silicon diodes, mercury arcs, etc. What is the symbol for rectifier? We will explain in detail below - joinwinchips

What is the symbol for rectifier?

The text symbol for rectifiers is TB, and the old standard can be used to indicate rectifiers with U.

Rectifier principle

In two basic types of rectifiers based on high-power diodes or thyristors, the high-voltage AC power from the grid is converted into DC power by a transformer

Diode rectifiers

The simplest of all rectifier types is the diode rectifier. In its simplest form, the diode rectifier does not provide any kind of means of controlling the output current and voltage values. In order to be suitable for industrial processes, the output values must be

controllable within a certain range. This control can be accomplished by applying a mechanical so-called on-load tap converter. As a typical case the on-load tap converter controls the input AC voltage at the primary side of the rectifier transformer and is therefore

also able to control the DC value of the output within a certain range.

Thyristor Rectifiers

Very close in design to the diode rectifier is the thyristor rectifier. Because the electrical parameters of the thyristor rectifier are controllable, there is no need for an on-load tap changer or saturation reactor.

Because the thyristor rectifier contains no moving parts, maintenance of the thyristor rectifier system is reduced. One advantage noted is the faster regulation of Lichtenmall thyristor rectifiers compared to diode rectifiers. During steps in the process characteristic the

thyristor rectifier is often regulated so quickly that overcurrents can be avoided. The result is that the overload capacity of a thyristor system can be designed to be smaller than that of a diode system.

Role of rectifiers

The function of a general rectifier is to convert alternating current to direct current, the so-called AC-DC conversion.

Rectification is generally required to multiply the voltage, so the multiplier rectifier is more varied, common to the simple multiplier rectifier circuits, half-wave multiplier rectifier circuits, Shinkel multiplier rectifier circuits and symmetrical multiplier rectifier circuits and

so on.

Principle of rectifier transformer

The principle of rectifier transformer is the same as that of ordinary transformer. Transformer is made according to the principle of electromagnetic induction, a kind of equipment to change the AC voltage. Transformers generally have a primary and secondary two

mutually independent windings, these two windings share a core. Transformer primary winding connected to the AC power supply, in the winding flow through the alternating current generates magnetic potential, so in the closed core there is alternating magnetic

flux. Primary and secondary windings cut the magnetic lines of force, in the secondary can be induced the same frequency of alternating current. The primary and secondary windings of a transformer have a turns ratio equal to the voltage ratio. For example, the

primary winding of a transformer is 440 and the secondary is 220. The primary input voltage is 220V in the secondary of the transformer will be able to get 110V output voltage Some transformers can have more than one secondary winding and taps, so that you can

get more than one output voltage!

Characteristics of rectifier transformers

Rectifiers and rectifiers to form rectifier equipment in order to obtain DC power from the AC power source transformer. Rectifier is the most commonly used DC power source in modern industrial enterprises, widely used in DC power transmission, power traction, steel

rolling, electroplating, electrolysis and other fields.

The primary side of the rectifier transformer is connected to the AC power system, called the network side, and the secondary side is connected to the rectifier, called the valve side. The structure principle of rectifier transformer and ordinary transformer is the same,

but because of its load rectifier and general load is different and has the following characteristics.

(1) the rectifier arms take turns to conduct in a cycle, the conduction time accounts for only a part of a cycle, so the current waveform flowing through the rectifier arm is not sinusoidal, but close to the intermittent rectangular wave, the original and secondary

windings in the current waveform are also non-sinusoidal. The figure shows the current waveform of three-phase bridge Y/Y connection. With thyristor rectification, the larger the hysteresis angle of the current undulation steeper, the current in the harmonic

components are more, which will make the eddy current losses increase. As the conductive time of the secondary winding accounts for only part of a cycle, the rectifier transformer utilization is reduced. Compared with the ordinary transformer, under the same

conditions, the rectifier transformer volume and weight are larger.

(2) ordinary transformer primary and secondary power is equal (ignoring losses) transformer capacity is the original winding (or secondary winding) capacity. But for rectifier transformer, the original, vice winding power may be equal, may not be equal (when the

original, vice current waveforms are different at the same time, such as half-wave rectifier), so the capacity of rectifier transformer is the original, vice side of the apparent power of the average, known as the equivalent capacity, i.e., S1 for the original side of the

apparent power, S2 for the vice side of apparent power

(3) compared with ordinary transformers, rectifier transformer ability to withstand short-circuit electric power must strictly meet the requirements. Therefore how to make the product has short-circuit dynamic stability, is an important topic in the design, manufacturing

Electrochemical industry

---- This is the application of rectifier transformers the most industries, electrolysis of non-ferrous metal compounds to produce aluminum, magnesium, copper and other metals; electrolysis of table salt to produce chlor-alkali, electrolysis of water to produce hydrogen and oxygen

DC power supply for traction

---- is used in the DC power grid of mine or city electric locomotive. Due to the valve side connected to the overhead line, short-circuit faults are more, DC load changes in large spokes, the motorcycle often start, resulting in varying degrees of short-term overload. For this reason, the temperature rise limit and current density of these transformers are low. The impedance is about 30% larger than that of the corresponding power transformer.

DC power supplies for transmission

---- are mainly used to supply DC motors in power transmissions, such as the armature and excitation of rolling mills.

DC Transmission

---- The voltage of this type of rectifier transformer is generally above 110kV, and the capacity is in the tens of thousands of kVA. Need to pay special attention to the ground insulation of AC and DC superposition problems.

In addition, there are electroplating or electroprocessing DC power supply, excitation DC power supply, charging and electrostatic dust removal DC power supply.

Reasons for using rectifier transformers

Application of rectifier transformer most of the chemical industry, high-power rectifier is also the secondary voltage is low, the current is very large, and therefore very large, so they are similar in many ways with the furnace transformer, that is, the structure of the

previously described characteristics of the point, the rectifier transformer also has the same. Rectifier transformer is the biggest feature of the secondary current is not sinusoidal alternating current, due to the subsequent rectifier components of the unidirectional

conduction characteristics, the phase line is no longer at the same time, the flow of the load current but the soft current conductive, unidirectional pulsating current by the filtering device into a DC current, rectifier transformer's secondary voltage, current is not only

connected to the group with the capacity of the connection, such as the commonly used three-phase bridge rectifier line, double inverse with balanced reactor rectifier line For the same DC output voltage, current required rectifier transformer secondary voltage and

current is not the same, so the rectifier transformer parameter calculation is based on the premise of the rectifier line, the general parameter calculation is from the secondary side to the primary side of the projection.

As the rectifier winding current is non-sinusoidal contains many high harmonics, in order to reduce the harmonic pollution of the grid, in order to improve the power factor, must improve the rectifier pulse number, which can be solved by the method of phase shifting.

The purpose of phase shifting is to make the rectifier transformer secondary winding of the same name between the end line voltage has a phase shift

Phase shifting method of rectifier transformer

The simplest method of phase shifting is to use two windings on the secondary side that are quantitatively and angularly coupled, which can double the number of pulses in the rectifier.

For high-power rectifier equipment, the need for pulse wave number is also more, the pulse wave number of 18, 24, 36, etc. Increasing application of this must be set in the primary side of the rectifier transformer phase-shifting winding to phase shift. There are three

types of phase shifting windings connected to the main winding, namely zigzag, hexagonal and extended triangle.

Rectifier transformers used in the electrochemical industry have a much wider regulating range than furnace transformers. For chemical salt electrolysis the regulating range is usually 55% - 105%, for aluminum electrolysis the regulating range is usually 5% - 105%.

Commonly used regulators such as electric furnace transformers have variable flux regulator, series transformer regulator and autotransformer regulator. In addition, due to the characteristics of the rectifier element, the valve side of the rectifier can be directly

controlled in the rectifier furnace silicon rectifier element conduction phase angle, you can smoothly adjust the average value of the rectifier voltage, this regulator is known as phase-controlled voltage regulation. Realization of phase-controlled voltage regulation, one

is the use of crystal valve tube two is the use of self-saturated reactor, self-saturated reactor is basically composed of a core and two windings, one is the work winding, which is connected in series between the secondary winding of the rectifier transformer and the

rectifier, the flow of current through the load, and the other is the DC control winding is provided by the other DC power DC current, the main principle of the use of ferromagnetic materials, nonlinear The main principle is to utilize the nonlinear change of

ferromagnetic material, so that the working winding reactance value has a great change. Adjustment of DC control current, you can adjust the phase control angle, thus adjusting the average rectifier voltage.