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Thyristor power controllers (SCR power controllers) control power or voltage supplied to a load. Typical applications are generally found where power needs to be varied and ultimately converted into thermal energy. For example, the controllers are used in industrial furnace construction and in plastic processing.
Thyristor power controllers are operated with an alternating voltage in single-phase or three-phase. They are controlled by a controller and vary the activation time of the mains voltage for the load.
Where the operating conditions allow, the pulse group operation is recommended.[ by whom? ] Here, whole mains voltage shafts are switched to the load or blocked. For example, a controller requires 60% output (via a 4–20 mA signal, which corresponds to 0-100%). The thyristor power controller switches 60% of the solid waves to the load while blocking 40%. The operating mode is to be regarded as unproblematic. Only in the case of a too weakly designed network, it is possible for illuminating installations which are connected to the same network to have undesired luminance fluctuations (flicker effect). Some operating conditions require switching in each half-wave and thus very fast operation. Examples are control sections with very fast behavior or a required current limitation with low element resistance in the cold state. In this operating mode, the controller changes the phase angle α of the thyristor ignition timing. A half wave corresponds to 180 ° el. (electrical degree). The actuator can adjust the phase angle of 0 ° el. (maximum power) up to 180 ° el. (no power). In a 50 Hz mains the controller switches every 20 ms and shows very fast behavior. As a result of the voltage flanks during switch-on, disadvantages such as EMC interference potential or control voltage output also result in ohmic loads. This situation must be counteracted by means of line filters or the corresponding plant size with compensating systems.
The controllers change their on-off ratio due to the degree of regulation. With a required output of 50%, the controller would switch off a full wave and a full wave in the pulse group mode. Only in the light of this situation, changes in output voltage fluctuate during mains voltage fluctuations. In fact, the operators have a subordinate regulation. In the most complex case, they vary the output power proportionally to the degree of regulation. For mains voltage changes, the controllers react with the variation of the switch-on and switch-off ratio.
In addition to the current limitation, thyristor power controllers offer additional functionalities for monitoring and / or protecting the elements: Heating elements are often operated in parallel. The partial breakage monitoring signals the breakage of a heating element. The heating element can be replaced at the next plant shutdown. R-Control limits the temperature of temperature-sensitive heating elements. Most of the heating elements are thermistors, they increase the resistance with the temperature. At a maximum permissible temperature, the heating element has a defined resistance, which is defined on the actuator. The output power is limited by the actuator and the maximum permissible temperature is not exceeded.
A rectifier is an electrical device that converts alternating current (AC), which periodically reverses direction, to direct current (DC), which flows in only one direction. The reverse operation is performed by an inverter.
A thyristor is a solid-state semiconductor device with four layers of alternating P- and N-type materials used for high-power applications. It acts exclusively as a bistable switch, conducting when the gate receives a current trigger, and continuing to conduct until the voltage across the device is reverse-biased, or until the voltage is removed. There are two designs, differing in what triggers the conducting state. In a three-lead thyristor, a small current on its Gate lead controls the larger current of the Anode to Cathode path. In a two-lead thyristor, conduction begins when the potential difference between the Anode and Cathode themselves is sufficiently large.
A power supply is an electrical device that supplies electric power to an electrical load. The main purpose of a power supply is to convert electric current from a source to the correct voltage, current, and frequency to power the load. As a result, power supplies are sometimes referred to as electric power converters. Some power supplies are separate standalone pieces of equipment, while others are built into the load appliances that they power. Examples of the latter include power supplies found in desktop computers and consumer electronics devices. Other functions that power supplies may perform include limiting the current drawn by the load to safe levels, shutting off the current in the event of an electrical fault, power conditioning to prevent electronic noise or voltage surges on the input from reaching the load, power-factor correction, and storing energy so it can continue to power the load in the event of a temporary interruption in the source power.
A power inverter, inverter or invertor is a power electronic device or circuitry that changes direct current (DC) to alternating current (AC). The resulting AC frequency obtained depends on the particular device employed. Inverters do the opposite of rectifiers which were originally large electromechanical devices converting AC to DC.
A switched-mode power supply is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently.
A thermostat is a regulating device component which senses the temperature of a physical system and performs actions so that the system's temperature is maintained near a desired setpoint.
A DC-to-DC converter is an electronic circuit or electromechanical device that converts a source of direct current (DC) from one voltage level to another. It is a type of electric power converter. Power levels range from very low to very high.
A voltage regulator is a system designed to automatically maintain a constant voltage. A voltage regulator may use a simple feed-forward design or may include negative feedback. It may use an electromechanical mechanism, or electronic components. Depending on the design, it may be used to regulate one or more AC or DC voltages.
Power electronics is the application of electronics to the control and conversion of electric power.
A variable-frequency drive, variable-speed drives, AC drives, micro drives, inverter drives, or drives) is a type of AC motor drive that controls speed and torque by varying the frequency of the input electricity. Depending on its topology, it controls the associated voltage or current variation.
Electric heat tracing, heat tape or surface heating, is a system used to maintain or raise the temperature of pipes and vessels using heat tracing cables. Trace heating takes the form of an electrical heating element run in physical contact along the length of a pipe. The pipe is usually covered with thermal insulation to retain heat losses from the pipe. Heat generated by the element then maintains the temperature of the pipe. Trace heating may be used to protect pipes from freezing, to maintain a constant flow temperature in hot water systems, or to maintain process temperatures for piping that must transport substances that solidify at ambient temperatures. Electric trace heating cables are an alternative to steam trace heating where steam is unavailable or unwanted.
A low-dropout regulator is a DC linear voltage regulator that can regulate the output voltage even when the supply voltage is very close to the output voltage.
Phase-fired control (PFC), also called phase cutting or "phase angle control", is a method for power limiting, applied to AC voltages. It works by modulating a thyristor, SCR, triac, thyratron, or other such gated diode-like devices into and out of conduction at a predetermined phase of the applied waveform.
An induction heater is a key piece of equipment used in all forms of induction heating. Typically an induction heater operates at either medium frequency (MF) or radio frequency (RF) ranges.
The Amplitude adjusting enables the power control of electric loads, which are operated with AC voltage. A representative application is the heating control of industrial high temperature furnaces.
An infinite switch, simmerstat, energy regulator or infinite controller is a type of switch that allows variable power output of a heating element of an electric stove. It is called "infinite" because its average output is infinitely variable rather than being limited to a few switched levels. It uses a bi-metallic strip conductive connection across terminals that disconnects with increased temperature. As current passes through the bimetal connection, it will heat and deform, breaking the connection and turning off the power. After a short time, the bimetal will cool and reconnect. Infinite switches vary the average power delivered to a device by switching frequently between on and off states. They may be used for situations that are not sensitive to such changes, such as the resistive heating elements in electric stoves and kilns.
Voltage optimisation is a term given to the systematic controlled reduction in the voltages received by an energy consumer to reduce energy use, power demand and reactive power demand. While some voltage 'optimisation' devices have a fixed voltage adjustment, others electronically regulate the voltage automatically.
A voltage controller, also called an AC voltage controller or AC regulator is an electronic module based on either thyristors, triodes for alternating current, silicon-controlled rectifiers or insulated-gate bipolar transistors, which converts a fixed voltage, fixed frequency alternating current (AC) electrical input supply to obtain variable voltage in output delivered to a resistive load. This varied voltage output is used for dimming street lights, varying heating temperatures in homes or industry, speed control of fans and winding machines and many other applications, in a similar fashion to an autotransformer. Voltage controller modules come under the purview of power electronics. Because they are low-maintenance and very efficient, voltage controllers have largely replaced such modules as magnetic amplifiers and saturable reactors in industrial use.
This glossary of electrical and electronics engineering is a list of definitions of terms and concepts related specifically to electrical engineering and electronics engineering. For terms related to engineering in general, see Glossary of engineering.
This glossary of power electronics is a list of definitions of terms and concepts related to power electronics in general and power electronic capacitors in particular. For more definitions in electric engineering, see Glossary of electrical and electronics engineering. For terms related to engineering in general, see Glossary of engineering.
