A power conductive electrode arm is an important part of an electric furnace. A good conductive cross arm should have the advantages of excellent conductivity, good processability, the long service life of all parts, convenient inspection and replacement of vulnerable parts, etc.
There are two kinds of power conductive electrode arms: copper steel composite arm and aluminum alloy arm. Recently, most of the domestic copper steel composite conductive cross arms have been replaced by aluminum alloy arms in Japan. Especially because the DC power supply has no skin effect, the copper steel composite plate conductive cross arm is not suitable. There are many advantages to using aluminum alloy conductive cross arms in DC electric arc furnaces. Due to its lightweight, the aluminum alloy arm further improves the speed and control performance of electrode lifting. Because vibration attenuation can improve the stability of the arc and increase the arc power, this is the reason to choose an aluminum alloy arm.
The conductive cross arm is a component of the electrode lifting mechanism of a modern electric arc furnace. The conductive cross arm cancels the conductive copper tube structure, so that the cross arm can be used as both a supporting part and a conductive part, simplifying the short net structure. In the arrangement, the two-phase conductive cross arms are symmetrically arranged relative to the middle phase conductive cross arms. The spacing should be as small as possible under the allowable conditions, which can reduce the structural size of the furnace, but it must also take into account the convenience of installation and adjustment of the column guide wheel, so the size cannot be too small. The elevation of the middle phase is based on the needs of the short network layout, and the value of its elevation dimension is obtained from the three-phase balance calculation of the short network.
1. Characteristics of Conductive Electrode Arm:
High power input improves production efficiency;
The impedance and reactance indexes are improved;
The arc has good symmetry and stability, and the pitch diameter is small, which reduces the consumption of refractory materials;
The electrode cross arm is rigid, and the electrode can be adjusted quickly without causing large system vibration;
Effective cooling and insulation of electrode cross arm;
The maintenance workload is reduced.
2. Composition of EAF Electrode Arm:
The conductive cross arm is composed of an electrode spray ring, electrode hoop, electrode chuck, electrode soot blower, electrode clamping system, cross arm body, water inlet pipe, water return pipe, oil inlet pipe, metal hose and water-cooling cable connecting plate.
3. Power Conductive Electrode Arm body:
3.1 Shape of Power Conductive Electrode Arm:
The conductive cross arm is generally a rectangular body with a height greater than width. There are two cooling methods: hollow sandwich water cooling and overall water cooling, and most of them are made of internal and external sandwich overall water cooling.
In the early days of the invention of the conductive cross arm, the inner and outer shapes of the hollow sandwich water-cooled conductive cross arm were designed into rectangles. Due to the existence of welds, water leakage often occurs under high temperature and strong water pressure, and under the action of frequent up and down irregular movement and vibration. Once there is internal water leakage, it is not only difficult to find the water leakage point, but also very difficult to repair even if the water leakage point is found. Moreover, there is a magnetic field inside the cross arm, which also leads to the seal of the electrode clamping cylinder installed inside the cross arm, which is easy to be damaged due to overheating due to eddy current. Later, the material was changed to solve the problems of oil leakage and eddy current, which not only greatly improves the service life, but also reduces the amount of maintenance.
The interior of the overall water-cooled conductive cross arm is full of cooling water. In order to make the cooling effect better, the cross arm is made into upper and lower compartments, and the cooling water enters from the lower layer and flows out from the upper layer.
3.2 Materials of Conductive Cross Arm:
The conductive cross arm is made of a copper steel composite plate: the outer layer is a copper plate and the inner layer is a steel plate, which is welded together by the explosion.
The outer part of the conductive cross arm is usually made into a rectangle, the outer copper plate is used for conducting electricity, and the inner steel plate is used as the support arm. Replace conductive copper pipe with copper plate. It can greatly increase the conductive area, greatly reduce the reactance and resistance value, and increase the active power by 3%-6%.