ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING car starter
Encyclopedia of radio electronics and electrical engineering / Automobile. Electronic devices The use of a starting device will be especially useful for car enthusiasts who operate the car in the winter season, as it extends the battery life and also allows you to start a cold car in winter without problems, even if the battery is not fully charged. It is known from experience that at sub-zero temperatures, the battery reduces its return by 25 ... 40%. And if it is not yet fully charged, it will not be able to provide the initial current of 200 A required to start the engine. This current is consumed by the starter at the initial moment of spinning the engine shaft (the rated current consumption of the starter is about 80 A, but at the time of starting it is much more).
The simplest calculations show that in order for the starting device to work effectively when connected in parallel with the battery, it must provide a current of at least 100 A at a voltage of 10 ... 14 V. In this case, the rated power of the used network transformer T1 (Fig. 4.1) must be at least 800 watts. As you know, the rated operating power of the transformer depends on the cross-sectional area of the magnetic circuit (iron) at the location of the windings.
Rice. 4.1. Starter circuit The starting device circuit itself is quite simple, but requires the correct manufacture of a network transformer. It is convenient to use toroidal iron from any LATRA for it - this results in the minimum dimensions and weight of the device. The perimeter of the iron section can be from 230 to 280 mm (it differs for different types of autotransformers).
Before winding the windings, it is necessary to round off the sharp edges on the edges of the magnetic circuit with a file, after which we wrap it with varnished cloth or fiberglass.
The primary winding of the transformer contains approximately 260 ... 290 turns of PEV-2 wire with a diameter of 1,5 ... 2,0 mm (the wire can be of any type with varnish insulation). The winding is distributed evenly in three layers, with interlayer insulation. After completing the primary winding, the transformer must be connected to the network and the no-load current must be measured. It should be 200...380 mA. In this case, there will be optimal conditions for transforming power into a secondary circuit. If the current is less, part of the turns must be unwound, if more, wind up until the specified value is obtained. It should be borne in mind that the relationship between the inductive reactance (and hence the current in the primary winding) and the number of turns is quadratic - even a slight change in the number of turns will lead to a significant change in the current of the primary winding.
When the transformer is in idle mode, there should be no heating. The heating of the winding indicates the presence of interturn short circuits or the punching and closing of part of the winding through the magnetic circuit. In this case, the winding will have to be done again.
The secondary winding is wound with insulated stranded copper wire with a cross section of at least 6 sq. mm (for example, PVKV type with rubber insulation) and contains two windings of 15 ... 18 turns. The secondary windings are wound simultaneously (with two wires), which makes it easy to obtain their symmetry - the same voltage in both windings, which should be in the range of 12 ... 13,8 V at a nominal mains voltage of 220 V. It is better to measure the voltage in the secondary winding temporarily connected to the terminals X2, X5 load resistor with a resistance of 10 ... XNUMX Ohm.
The connection of rectifier diodes shown in the diagram makes it possible to use the metal elements of the body of the starting device not only for mounting diodes, but also as a heat sink without dielectric spacers ("plus" of the diode is connected to the mounting nut).
To connect the starting device in parallel with the battery, the connecting wires must be insulated and stranded (preferably copper), with a cross section of at least 10 square meters. mm (not to be confused with diameter). At the ends of the wire, after tinning, the connecting tips are soldered.
The contacts of the switch S1 must be rated for a current of at least 5 A, for example, type ТЗ. Publication: cxem.net
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