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In order to ensure the safety of railway traffic and reduce manual operation, it is necessary to control railway electrical signals through automatic control system. Safety relay is the main product of railway signal relay and the main automatic control equipment for railway electrical signal control. This paper will discuss the safety relay of railway signal equipment to improve the operation efficiency of automatic control technology of railway signal equipment.
Keywords: automatic control technology of railway signal safety relay
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Railway is the main artery of China's national economy and plays an important role in promoting China's economic development. Especially in recent years, with the rapid development of China's economy and the continuous improvement of people's living standards, people have put forward higher requirements for the rapidity and safety of transportation. In order to ensure the safety and stability of railway transportation, the effective control of railway signal equipment failure has become one of the main keys to improve the safety factor, and it is also an important guarantee to ensure the safe and orderly operation of railways. Railway signal equipment is one of the main railway equipment, and its function is to play an important role in organizing and directing the safe operation of trains, improving the efficiency of train transportation, transmitting all kinds of transportation information and improving the working conditions of drivers. Its importance is self-evident. In order to ensure the safety of railway traffic and reduce manual operation, it is necessary to control railway electrical signals through automatic control system. Safety relay is the main product of railway signal relay and the main automatic control equipment for railway electrical signal control.
I. Overview of Safety Relay
Safety relay is a special relay for railway signal designed and produced by our country. It is a 24V DC series heavy elastic DC electromagnetic relay, which works by the return of heavy elastic force. Its basic structure is a ring relay. The structure consists of an electromagnetic system and a contact system, wherein the electromagnetic system comprises a coil, a fixed iron core, a yoke and a moving armature, and the contact system comprises a pull rod and a static and dynamic contact group. Principle of action: When a certain amount of current flows into the coil, electromagnetic attraction is generated due to electromagnetic action or induction, attracting the armature, which drives the contact system to change the state, thus reflecting the state of the input current. It can also be said: electricity → magnetism → force → action lever, F gravity >; F gravity is in a state of attraction. There are two types of safety relays: plug-in (with C in the model) and non-plug-in. In signal equipment, plug-in type is mostly used alone, and non-plug-in type is mostly used for box-type equipment with dust-proof shell.
Second, the application of relay in railway signal.
In railway communication signal, the selection of relay, the expression of relay name and the positioning of relay are very important, so as to be used in relay more safely and effectively.
1, relay selection principle. First of all, we should understand the principle, technical parameters, working conditions, structural and technological characteristics and specifications of the relay, as well as the coil resistance, the characteristics of the controlled circuit and the requirements for the relay to meet the basic requirements of each circuit. Secondly, we should understand the key technical performance of relay, especially the contact load, action time parameters, electromechanical life and so on. Especially when series relays are used in railway circuits, the number of series relays meets the voltage requirements. The current flowing through the relay contact should not be less than the working current of the circuit, and parallel technology should be adopted when it cannot meet the requirements. When the number of relay contacts is insufficient, especially when the circuit requirements cannot be met, a relay relay is set to reflect the working state of the main relay. When relay contacts are connected in series in the circuit, the contact resistance of the contacts meets the requirements of the circuit, and the principle is to better meet the normal operation of the circuit.
2. Description of relay. The name symbols of relays are generally named according to their main uses and functions, such as AJ for button relays and XJ for signal relays. Many relays will be used for the same function and function, and their names must be distinguished. Such as XLAJ, SLAJ, etc. XLA, which represents the route button relay of the descending station signal train, and STAJ, which represents the ascending button relay, must be marked with the name symbol of the same relay to avoid confusion with each other. In addition, the contact groups of the same relay should be distinguished by their numbers to prevent reuse.
3. Positioning of relay. There are two kinds of relays: up state and down state. Only one of these two states can be represented in the circuit diagram. The state of relay in the circuit diagram is called normal state or positioning state. In the railway signal system, the following principles should be followed to specify the positioning state. First, the positioning state of relay should be consistent with the positioning state of equipment, and the equipment state reflected in the signal layout is agreed as the positioning state of equipment. For example, the signal is usually in the off position; The switch is in the open position and the track circuit is in the idle position. Secondly, according to the principle of failure and safety, the falling state of relay is required to be the same as that of safety side of equipment. For example, the drop of signal relay should be consistent with the signal closing, and the drop of track relay should be consistent with the occupation of track circuit. In this way, when the circuit is disconnected, it can be guided to the safe side. In the circuit, as long as the relay is in the up position, its contacts and coils are represented by "↑", and as long as the relay is in the down position, its contacts and coils are represented by "↓". The third is the symbol of relay. For the coil, the positioning state arrow and the coil terminal number must be marked. The front contact and rear contact of relay are only marked with contact group number, and it is not necessary to mark the moving contact, front contact and rear contact number in detail.
Third, the maintenance and adjustment of safety relay
In the application of railway signal equipment, some problems will inevitably occur, so it is necessary to do a good job in the maintenance and adjustment of safety relays.
1, electromagnetic system maintenance. The overhaul of electromagnetic system includes the overhaul of coil and magnetic circuit, and the magnetic circuit also includes the cleaning of steel wire clamp, yoke, armature and magnetic system. When checking the coil, if the mechanical strength is not affected by damage, epoxy resin shed can be used to repair it. Suppose the coil leads have broken strands and false welding problems, and need to be re-welded. In the maintenance of magnetic circuit, it is necessary to check whether the armature is deformed and whether the armature is parallel to the surface of the iron core when working. At the same time, we should pay attention to the uniform guarantee of air gap to make it have good magnetic permeability. When the armature is twisted, it should be repaired on the workbench. Assuming that the armature blade is seriously worn, it should be repaired with a fine file. If it is not repaired well, it should be replaced in time.
2. Contact system maintenance. Maintenance of the contact system, including whether there are scars on the support piece and the contact piece, whether the coating is intact and whether the welding between the contact piece and the silver contact is firm. For the pull rod, insulated shaft and moving contact shaft, the pull rod should be installed straight and not deviate from a fixed angle. The deviation angle should be corrected.
3, adjust the magnetic circuit and contact system work. First, adjust the gap between the contact frame and the yoke. Assuming that the gap does not reach the standard of 4mm, it is necessary to take it out for repair and adjust the angle and installation height of the contact frame. After this step is completed, screw it, drill the hole again and fix the nail. Second, the angle of the armature, first take out the armature, measure the angle of the armature with a protractor, and determine the angle according to the gap value. Three, armature free fall, check with a feeler gauge. The armature stroke is the same as that of the rear contact, and the pressure of the rear contact needs to be measured by dynamometer. It also includes adjusting the initial pressure of back contact; Adjust the position of the rear contact and the clearance after moving; Adjust the contact uniformity of the contacts; The clearance distance between the lower stop and the counterweight is 0.3 mm ~ lmm, which should be adjusted. And electrical characteristic test.
refer to
[1] Longfan. Thoughts on Railway Signal Engineering Construction [J]. Management and Technology of Small and Medium-sized Enterprises, 20 1 1(4).
[2] Ching Ching Chang. Design and Research of Railway Signal Equipment Fault Diagnosis Expert System [J]. Enterprise Technology Development.2016 (09)
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