Classification of Power Electronic Devices for Stainless Steel Cable Joints
Motivation provides different polarity, different voltage, different frequency, different phase sequence of the supply voltage of the purpose, in order to control the motor starting and stopping, steering and speed.
Power electronic devices according to their characteristics can be divided into two branches: First, the thyristor as the representative of the semi-control device; Second, the new variety of full-controlled devices, such as power transistor (GTR), can turn off the thyristor (GTO ), A power field effect transistor (power MOS-FET), an insulated gate bipolar transistor (IGBT), and the like.
As the semi-controlled thyristor device can only control its opening, can not control its turn off, so in the composition of the inverter circuit is more difficult, there are lines of complex, low reliability shortcomings. Currently in the DC motor speed control system is still in use, almost all other areas of the use of full control devices.
Full-controlled power electronic devices according to its structure and working mechanism is divided into three types: bipolar, unipolar and hybrid.
Bipolar device refers to the device inside the electronic and hole two carriers at the same time involved in conductive devices, common GTR, GTO, etc., such devices are characterized by large capacity, but the operating frequency is low, and there are two Sub-breakdown phenomenon and other weaknesses.
Unipolar device refers to the device only one carrier, that is, only the majority of carriers involved in conductive devices, the typical representative of the power MOSFET, the device operating frequency is high, no secondary breakdown phenomenon, but the current capacity Not like bipolar type.
Hybrid device refers to the bipolar type and unipolar device integration and integration, both the advantages of both, the most promising. IGBT is a typical representative, in addition to multi-functional intelligent power integrated circuits.
Stainless steel cable bridge common four major types of failure
The first type of failure: the entire cable was blown or a phase was blown, such failure caused by the power distribution cabinet on the relay action, the cable damage in the fault is quite serious.
The second type of fault: the cable phase is short-circuit, the same, such failure caused by the distribution cabinet current relay and voltage relay are action, the cable is damaged in the fault point is also very serious
The third type of fault: cable bridge only one phase of the circuit, the current relay action, the fault point of damage is lighter but more obvious. It may be that the phase current is too large or is caused by cable quality.
The fourth type of fault: cable internal short circuit, the appearance of no trace, such failures are generally due to the cable quality is relatively rare.
The stainless steel cable bridge can be used as an independent erection of the bridge within the building. It can also be attached to various structures and corridors. It should be characterized by simple structure, beautiful appearance, flexible configuration and convenient maintenance. All parts are Need to be galvanized, installed in the building outside the bridge.
Stainless steel cable bridge is divided into trough, tray and ladder-type, mesh and other structures, by the bracket, arm and installation accessories and other components.
Stainless steel cable bridge as a wiring project supporting a project, there is no special specification guide, a manufacturer of the lack of generic specifications of the program, therefore, the selection process should be based on weak system of each system cable type, the number of reasonable selection of applicable Bridge.
Stainless steel cable tray horizontal mounting bracket spacing: 1.5-3 meters, vertical mounting bracket spacing: not more than 2 meters;
The top of the cable bracket from the top of the shaft or the top of the floor is not less than 150-200mm, the bottom of the cable bracket bottom or the ground is not less than 50-100mm;
Metal pipe is not allowed to melt welding connection, galvanized and wall thickness of less than 2mm of the steel pipe shall not be welded pipe welding;
Under the outdoor floor laying steel pipe, buried depth should not be less than 0.7 meters, wall thickness should not be less than 2mm.
No design requirements, buried in the wall or concrete within the wire, the use of medium-sized catheter;
Through the flexible catheter and electrical equipment connected, the power equipment is not greater than: 0.8 meters, lighting equipment is not greater than: 1.2 meters.
Cable bridge for general industrial and mining enterprises indoor and outdoor overhead laying power cables, control cables, can also be used for telecommunications, radio and television departments in the indoor and outdoor erection.