Personal connections are included in the all-electricchain and are very responsible elements. From the state of the electrical contact connections depends on trouble-free operation of electrical equipment and wiring.
This important transition magnitude of the contact resistance.
In the circuit, the point of contacttwo or more conductors creates electrical contact transition, or a conductive connection through which a current flows from one part to another. By simply applying the contacting surface of the connected conductors makes good contact. The actual contact area is several times less than the entire contact surface, so that confirmation can be seen with a microscope.
Due to the small contact area of the contactcompound gives a very significant resistance to the passage of current from one surface to another, and the transition called contact resistance. Needless priori contact transfer resistance greater than the resistance of the continuous conductor of the same shape and size.
Factors affecting the value of transitional resistance
The resistance of the contact zone does not depend on the size ofcontact surfaces and determined pressure force or contact pressure force. Called contact pressing force with which a contact surface acting on the other. In general, on the size and strength of pressing forces of the contact material will depend on the total area of contact. The number of contact in their contact always grows when pressed.
At low pressure, the plasticcontact deformation, and the tops of the projections are crushed and then, with increasing pressure, more and more new terms come into contact. As a result, the pressure must be large enough to provide a small contact resistance, but also should not give rise to plastic deformation in metal contact, leading to its destruction.
Transient resistance largelyIt depends on the oxidation of contact surfaces of connected conductors. Regardless of conductor material, oxide film creates a larger electrical resistance.
Intensity conductors oxidation depends on the contact temperature, and it is faster than the more transfer resistance.
Very highly susceptible to oxidation aluminum conductors. For example, formed on the air of the oxide film has a resistivity of 1012 ohm * cm.
Since the properties of the compounds may contactchange. Only a new, well-crafted and stripped transitional contact may be the least likely transient contact resistance at a sufficient pressure.
When forming the contact connections are useddifferent ways of bonding conductors. For example, soldering, welding, crimping, mechanical connection by means of bolts, as well as bringing into contact with the elastic pressing means of springs.
In fact, in any method of connecting wiresYou can achieve consistently low contact resistance transition. It is important, at the same time, connect the wires strictly on technology and the use of each method for wiring the necessary tools and materials.
Contact connection electrochemically incompatible conductor is a contact of two oxides, which will have a high value of transitional resistance.
In order to reduce the transitional contactresistance to take into account all the above factors affecting its value and carry out appropriate types of conductors connecting contact materials and the conditions of their operation.