The necessity of copper aluminum terminal application
Current-carrying wires for copper wires in the contact rail, rail material for steel, aluminium, connected to current-carrying conductor for aluminum, the two metal interface is easy to form the electrolyte in the damp environment, make the contact rail electric connection produces galvanic corrosion, affect the service life of the contact rail electric connection and power supply security hidden danger exists.
In addition, due to the modulus of elasticity of copper, aluminum and the difference in thermal expansion coefficient, after psychro-thermal cycles for many times, will expand contact of the gap between seam, increases the resistance of copper aluminum contact area. If the contact resistance increases, it could cause contact surface temperature, in the operation of the high temperature oxidation corrosion would have a vicious cycle, increase the quality of copper aluminum connecting further deterioration, resulting in high temperature contact point even welding, burning and other accidents, serious impact on the safety operation of the urban rail transit power supply system.
Device according to the electrical installation project busbar is code for construction and acceptance of the specific provision: bus and bus, bus and branch line, busbar and electrical terminals, the lap surface treatment shall meet the following requirements: copper and aluminum: in dry indoor, tin copper conductor shall be in China. Nearly 100% of indoor or outdoor air relative humidity, should use transition copper aluminum plate, copper side should be lining tin. Accordingly, copper and aluminum cable connection can be used copper aluminum connecting pipe, copper and aluminum cable wire connection can use copper and aluminum terminals, copper end should be lining tin, etc.
Combining the above analysis and related regulations, copper wires and aluminum in contact rail electric connection plate connection while the copper and aluminum terminals.