In the 21st century, with the rapid development of railway, the speed per hour is faster and faster, and the marshalling operation is more and more intensive, it is necessary to ensure the normal operation of electrical service system. How to ensure the correctness of cable identification by live cable identification instrument, we will discuss and explain this problem below. In the electrical service support, the fault and construction of signal cable shall be tested and identified quickly. If the identification is wrong, it will have a very serious impact and cause train accidents. So let's talk about the identification of electrical service system. 1ã Current situation and disadvantages of signal cable identification in telecommunication system target cable identification is required in field work such as emergency repair, relocation and replacement of signal cable. Since there is no suitable instrument, most of our signal cable maintainers use the following methods to identify. First, wait for the skylight point, and remove the signal cable sheath when the skylight point; Secondly, two core wires are selected as the identification wire, and the two core wires are also found at the end; Finally, use the blade to cut the skin of the selected two core wires for short connection, and use the external meter to measure whether the selected two core wires are short circuited at the end. If they are short circuited, it means that the identification is accurate, otherwise, the identification is wrong. However, there are many disadvantages in using this method for identification: 1. Generally, such work is rush repair, which must be completed in the skylight point. If it takes up the time in the skylight point for identification, the rush repair time will be greatly reduced, and some even need to apply for two skylight points to complete a work; 2. After the selected two core wires are short circuited, the two core wires found at the end may not correspond, resulting in wrong results; 3. The outer skin and copper shield of the cable shall be broken. After identification, this place shall be restored. In the future, this place is a joint and a potential fault point. 4. The most important thing is that this identification often produces wrong results, resulting in operation accidents. 2ã Current status of cable recognizer 1. Current status of identification equipment (identification and attached identification): status of identification 1: conventional cable recognizer is designed for power cable identification and is widely used in the power field. Whether imported or domestic, it has two service conditions: 1) it has high requirements for the loop resistance of the target cable, Generally, it shall not exceed 50 ohms. If it exceeds the range of this circuit resistance, the equipment will not work normally, which is beyond the range of equipment use; 2) Disconnect at least one end of the outer armor grounding (same as shielding grounding) at both ends of the target cable, so that the applied signal cannot return from the target cable. Therefore, this power cable identification instrument is not suitable for the identification of electrical signal cables. Identification status II. When promoting digital path tester, some manufacturers publicize that the equipment has identification function. In fact, when using the digital path tester to identify, if the receiver touches the identified cable, which signal is the strongest, that is the identified cable. This recognition method has a single judgment basis in recognition, only the signal size, no signal direction, and can not be used as the final judgment. Moreover, such equipment has great attenuation on the signal cable, and the identification of long-distance signal cable can not be done at all. 2. Conclusion: the use conditions of power cable identification instrument and digital path tester determine that these two types of equipment are not applicable to the signal cable of electrical service system. 1) For the signal cable of electric service. The cable is very long, with a length of more than 5km, and some can reach more than 20km; The wire core is very thin, generally 1mm Â² ï¼ The resistance is 23.5 Î© per kilometer, and the cable body resistance of more than two kilometers has reached the critical value of equipment test, so the loop resistance problem has become a hard wound of the conventional identification instrument. 2) In the electrical service system, it is very inconvenient to open the outer armor grounding (the same as shielding grounding) of the signal cable. The regulations of each Railway Bureau and railway line are inconsistent. Some cannot be opened, some must be opened in the skylight point, and must be restored before the end of the skylight point. Based on the above two points, the conventional cable identifier and Pathfinder can not meet the requirements of signal cable identification of railway electrical service system. 3ã During the test of railway signaling cable identifier, the requirements for loop resistance can reach 1000 Î©, and there is no requirement for armored grounding or ungrounded of the target cable. The utility model solves the difficult problem of identifying the signaling cable. The railway communication cable is specially designed and can be used online. It has the characteristics of micro power transmitting signal, has no crosstalk and interference to the data transmission of adjacent cables, and accurately finds out the required cable. The size double jaw configuration can not only identify the cable, but also identify the wire pair in the cable. Color large screen LCD, live voice prompt, friendly intelligent man-machine interface, and its unique intelligent orientation can indicate the signal direction, which makes the operation simple and practical. It is especially suitable for field use. Even untrained personnel can use it quickly. Through live measurement, it is not necessary to apply for night skylight time to cut off and repair cables. Workers in the front-line electrical service workshop can measure during the day, including when high-speed rail / Bullet train passes, which improves the timeliness and operability of detection.