- Design and operation principle
- Application area
Design and operation principle
First of all, let's talk about what this circuit element consists of and how it works. In the diagrams, the designation of the throttle is as follows:
The appearance of the product can be as shown in the picture:
This is a coil made of wire wound on a core with a magnetic circuit, or without a housing in the case of high frequencies. Looks like a transformer with only one winding. A short excursion into physics, the current in the coil can not instantly change. Let's conduct a mental experiment - we have an alternating current source, an oscilloscope, a choke.
During the beginning of the half wave, we observe an increase in current with a delay, this is caused by the induction of magnetic flux in the core. There is a gradual increase in the current in the windings, when the signal goes to the decay from the AC source, we see the current drop in the throttle, again with some delay, since the magnetic field in the magnetic circuit continues to push the current in the coil and can not quickly change its direction. It turns out at some point the current from an external source counteracts the current induced by the magnetic core of the throttle. In AC circuits, the purpose of the throttle is to act as a limiter or inductive resistor.
For direct current, this circuit element is not a resistance or a regulating element. This effect is used for devices in electrical circuits where it is necessary to limit the current to the desired value, while avoiding excessive unwieldiness and heat generation.
An interesting explanation on this subject can also be viewed on video:
Scope of application
The throttle is designed to make our life brighter. Specifically in fluorescent lamps, it limits the current through the flask, to the desired value, avoiding its excessive magnification through the lamp.
Fluorescent lamp mainly consists of a throttle, a starter, a fluorescent lamp. In a nutshell, the description of the fluorescent lamp works as follows:
From the mains, the current passes through the choke to one of the filaments of the fluorescent lamp, then goes to the starter device, then to the second filament and goes to the mains. In a starter device, a plate of bimetal is heated by a glow discharge of gas, straightened by heat and closes the circuit. At this moment, the filaments begin to work, at the ends of the bulb, heating up the mercury vapor in the bulb of the fluorescent lamp. After a short period of time, the plate in the starter cools down and returns to its original position. During the break of the circuit, a sudden surge of voltage in the throttle occurs, a gas breakdown occurs in the bulb of the fluorescent lamp, and a glow discharge occurs, the bulb starts to shine, the operating lamp shunts the starter, turning it off from the circuit by a lower resistance.
In electronic circuits of modern economic fluorescent lamps there is also an element considered in the article, but because of higher frequencies it has miniature dimensions. And the principle of work and appointment remained the same.
Also the throttle is an obligatory element in the schemes of DRL lamps, sodium lamps of DNAT, metal halide lamps CDM.
In pulse power supplies in converter circuits, the purpose of the throttle is to block sudden surges from the transformer, skipping the smoothed voltage. Roughly speaking, in this case it plays the role of a filter.
In electrical networks they are also installed, but are called reactors. The purpose of the arc extinguishing reactor is to prevent the emergence of an independent arc during a single-phase short circuit to earth, as well as other reactors that somehow regulate or limit the magnitude of the current through them, specifically or in case of an emergency situation.
With the help of a throttle it is possible to improve a cheap or self-made welding machine by setting it in the secondary circuit. The welding transformer assembled with the throttle will cook no worse than the branded apparatuses, the arc will become even and will not tear, the seam will be uniformly poured.
Arc arcing will become much easier and the network voltage drop will have less effect on the appearance and burning of the arc. Even an amateur can quickly achieve good results in welding, doing all kinds of crafts at home.
Here we have considered the throttle device, the principle of operation and purpose. We hope that now you have completely figured out what this element of the scheme is for!
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