Precautions for the most popular microcomputer pro

2022-08-26
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Precautions for using microcomputer protection device

microcomputer based relay protection device has the advantages of multiple functions, good flexibility, automatic monitoring and so on. At present, it has been widely used in relay protection. In order to give full play to its function and ensure the safe operation of power system, the author believes that the following matters should be paid attention to when using microcomputer relay protection device and designing hydraulic universal testing machine

1 precautions in relay protection design

(1) designers must be familiar with the model, principle, scope of application, technical requirements and software version number of microcomputer protection device. Know the program version of line opposite side protection

(2) in the design process, the interference of strong current to weak current circuit must be considered. Strong current and weak current shall not share one cable. When arranging the terminal strip of the protection screen, the strong current and weak current terminals shall be separated only by the appearance of words to determine the order of documents

(3) in order to prevent the interference of AC current, AC voltage and DC circuit from entering and causing the abnormal operation of the microcomputer protection device, anti-interference capacitors are designed to be installed at the inlet of the protected AC and DC power supply, and shielded cables must be selected for the current, voltage and signal incoming lines of the protection device

2 precautions in the installation of microcomputer protection device

(1) open the box on site to check whether the design of the protection device meets the requirements of "Four Unifications", and check whether there are strong and weak current circuits inside the device

(2) the wiring of the lead-in device terminal on the screen should be far away from the wires of the DC operation circuit and the wires of the high-frequency input (output) circuit, and must not be bundled together. The weak signal line shall be far away from the wire with strong interference, and the distance between all exposed live devices on the screen and the screen board shall be greater than 3 mm

(3) when laying cables, make full use of the shielding effect of natural shielding. If necessary, a special shielding wire or copper bar parallel to the protective cable can be set, and both ends of the shielding layer can be reliably grounded. Never use the simultaneous grounding of both ends of the spare core of the cable as an anti-interference method. In order to prevent the influence of high voltage, lightning, etc. on the storage capacity of the protection and the same amount of power as the traditional battery, the cable laying path for protection should be as far away from the high-voltage bus and the entry point of high-frequency current (such as the entry point of lightning arrester) as possible, and should be layered with the power cable

(4) the protective device box must be reliably connected to the special grounding copper bar set up by the protective screen with copper screws, and then the copper bar is connected to the grounding body of the control room

3 precautions during commissioning of microcomputer protection device

(1) confirm the protection before the human body touches the microcomputer protection. 1. Maintenance of the host of digital electronic tensile testing machine: the device box has been reliably grounded. The human body must discharge at the same grounding point as the grounding body of the protective device box. It is best that the human body is connected to the grounding body during the whole commissioning process

(2) during commissioning, the shells of all AC power testers (such as frequency signal generator and oscilloscope) must be grounded at the same grounding point as the protection device

(3) never plug in or unplug the plug-in during the test. Only after the power supply is disconnected can a special plug-in device be used to plug in or unplug the plug-in

(4) when the chip must be replaced during debugging, use a special puller to prevent human body from directly contacting the chip (anti-static damage). In case of component damage, the plug-in is generally replaced directly, and the plug-in is returned to the manufacturer for maintenance, without electric soldering iron as far as possible

(5) the power supply of the test device is directly connected from the terminal strip of the screen, not directly connected to the protection device

(6) since the protection may be interfered by high-energy radiation equipment during operation, the wireless signal sent by the radio interphone shall be used for interference test on the protection during commissioning, and no abnormality is allowed during the test

4 precautions for the operation of microcomputer protection device

(1) it is strictly forbidden for others to bring UV equipment into the control room to prevent UV from erasing the microcomputer protection chip program or causing the protection program to make mistakes

(2) in order to avoid human interference, operators should prevent others from using high-energy radiation equipment (such as walkie talkie) in the control room

(3) when the program version of microcomputer protection device needs to be upgraded, the protection on both sides of the line (mainly high-frequency protection) must be upgraded before it can be put into operation

(4) when the relay protection personnel input the fixed value of microcomputer protection, work inside the device, or work in the AC current, AC voltage, switching value input and output circuits used by the device, they must apply for stopping the whole set of microcomputer protection device

(5) the signal sent by the device should not be kept for a long time to prevent the central signal light plate circuit (strong current) from connecting to the protection weak current circuit and burning the components

(zhenghuafeng)

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