Auto Electrical Wire also named Automotive Electrical Wire is a general term for the wires used to connect all electrical equipment circles in automobiles. It includes low-voltage wires for lighting, alarms, indications, and other auxiliary electrical equipment connections; motor wires and battery connection wires for power supply, starting system and grounding wire; high-voltage ignition wire used for ignition system and other three categories.
Car electrical cable are commonly consumables for maintenance, and the sales and supply are large every year.
Motor wires, battery connection wires and grounding wires are actually low-voltage wires, but the current they pass through is often as much as 500-1000 amperes. The long wire cross-sectional area is much larger than other general low-voltage. There are 25, 35, 50, 70 mm2 and other specifications. The cross-sectional area of high-voltage ignition wire is very small, because the current passing through is very small so the voltage is very high, generally above 15,000 volts. Other low-voltage lines are divided into 1, 1.5, 2.5. 3, 4, 6, etc. according to the size of the working current required by the electrical equipment. Therefore, in the various circuits of the car, All three types of wires perform their own special tasks.
In the use of general specification low-voltage cables, it is very important to select a wire with a suitable cross-sectional area according to the operating current required by the electrical equipment. It is not only related to the normal running but also an effective saving measure (saving gold copper). Practice has proved that the selection of wires with too large cross-sectional area will result in waste;if it is too small, power supply will be insufficient, which will affect the inherent performance .For the motor wire of the power system, because of the large amount of copper used, more attention should be paid.
The selection of wire standard cross-sectional area (mm2) is based on the heating condition under the running current. Even in summer, the temperature near the engine can be as high as 70~90P, but the wire here should not exceed 10°C due to the current rise. For passing current is small, considering the need for the wire itself to have sufficient strength, its cross-sectional area should not be less than 0.5 mm2,. Table 15.56 for the allowable load current values of the for various copper core low-voltage lines Table 15-57 is the recommended value of the cross-sectional area of the main circuit conductors of the 12-volt automotive system.
As above mentioned, also whether it is suitable for use, we should check the wire voltage drop. No matter it is a single-wire system (using the frame as the return conductor ), or two-wire systems (using wires as loop wires, which are more common in spool trucks or buses with aluminum or wooden carriages) require the total max voltage drop of the entire vehicle circuit (excluding contact resistance) is 0.8v; when the generator is rated the max wire voltage drop is 0.3V: when the starter is braking the maximum voltage drop is 0.5V. As if the cross-sectional area is too small, the temperature rise of the wire will increase, and its resistance will also increase, no doubt the voltage drop will increase and the power supply will be insufficient.
Low Voltage Wire
There are two types of auto low-voltage cables, including motor cables. One is QVR with polyvinyl chloride jacket,the other is QFR type sheath of polyvinyl-butyronitrile compound. Both have good cold resistance, flexibility and certain oil resistance, non-flammability.While the QF type is softer and has a soft rubber feel. Both have good cold resistance, flexibility and certain oil resistance, non-flammability, while the QF type is softer and has a rubbery soft feel.
In recent years, due to the increasing number of electrical equipment used in automobiles, in order to facilitate installation and maintenance, the low-voltage cable with a single sheath color in the past has been replaced by a low-voltage cable with two colors of main color and auxiliary color. It is called two-color wire. According to our country’s JB/2-116-75 standard, except low-voltage wire with a cross-section more than 4 mm2 still use single color, cross-section area below 4 mm2 all use two-color wires. At the same time, it is stipulated that the main two-color color in the same power system should be the same as single color. If there is a branch through equipment, the auxiliary color should be selected from left to right as shown in Table above. The single black wire is specified as a grounding wire dedicated to electrical equipment.