In order to prevent electrical misoperation, the composition, working principle, installation points and wiring principle of the high-voltage live display device are analyzed. Combined with practical engineering applications, the application of high-voltage live display devices is discussed, and the use of high-voltage live display devices with electromagnetic locks, microcomputer five-proof equipment, and the application of electrical locks are mainly discussed. Based on work experience, relevant suggestions were put forward.
The high-voltage charged display device is a device that can transmit the signal of whether the high-voltage charged body is charged or not to the light-emitting or sound element, and display or lock the high-voltage switch equipment at the same time. High-voltage live display devices have been widely used in substations. This article discusses the design and application of high-voltage live display devices based on actual engineering.
1 High voltage live display device
1.1 Composition of the device
The high-voltage live display device is used to indicate the live status of high-voltage equipment and forcibly lock related equipment (grounding switch, switch cabinet door, net door, etc.). It is one of the important measures to ensure physical health. It includes two parts: sensor and display, as shown in the figure. 1 shown.
The sensor can be used in conjunction with various types of high-voltage switchgear, isolating switch, grounding switch, etc.; the display is divided into a prompt display and a mandatory display. The former is used to prompt the live status of high-voltage live equipment, and serves as a reminder for error prevention and security. In addition to the prompt display function, the latter can also be used in conjunction with electromagnetic locks and other anti-misoperation locks to forcibly lock the switch cabinet operating handles and net doors, etc., to prevent live grounding of the switch, prevent accidental entry of the live interval, and improve switch equipment Anti-error performance. In addition, in order to facilitate the user's on-site dual power nuclear phase, some display panels are equipped with a phase test terminal, which also serves as a "nuclear phase".
The sensor is inductive, which uses the principle of electric field coupling between the high-voltage electric field and the sensor to perform non-contact detection beyond a certain distance. The device adopts split-phase control, flashing alarm when any phase is electrified, and output a forced lock signal. When the monitor loses control power, the monitor outputs a forced lock signal to maintain the locked state.
The display is a continuous operation mode, with flash display, sound alarm and self-checking functions, and can output a forced lock signal. When the device under test or the network is electrified, the "power" indicator of the display is on, the "A, B, C" three-phase indicator lights are flashing, the "operation" indicator is off, and a forced locking signal is output.
When the device under test or the network is not powered, the "power" indicator of the display is on, the "A, B, C" three-phase indicator is off, the "operation" indicator is on, and the lock signal is released at the same time, and the device can be operated. The display is equipped with a "self-check" function, which can automatically detect the function modules of the sensor and the display. When the device has any failure, the "operation" indicator will not light up, and always output a forced lock signal to maintain the locked state.
1.2 Installation and wiring principle of the device
In practical applications, high-voltage live display devices are mainly installed in line grounding knives, bus-bar grounding knives, bus-bar voltage-changing grounding knives, switch cabinets and other places that need to be locked to implement forced locking to prevent electrical misoperation.
The wiring principle of the inductive sensor is shown in Figure 2. The sensor should be installed directly in front of the charged body, without direct contact with the high-voltage charged body, and keep a certain distance. It receives electric field signals from high-voltage charged objects and transmits them to the display. Under certain reliable measures, live installation can generally be carried out.
In order to eliminate the high-frequency interference in the surrounding space, three single-core shielded wires (5 in Figure 2) are used for the three phases, and the high-frequency interference can be eliminated through a good grounding of the shielding layer, which overcomes the anti-interference of the early inductive high-voltage charged display Disadvantages of weak ability.
Refer to Table 1 for the installation distance reference data of the sensors installed on site (different manufacturers’ products vary). Note: When the monitor is installed, the height from the ground should be at a position where the indicator light of the charged monitor can be visually observed.
2 Field application
The high-voltage live display device can detect whether the equipment has electricity at a certain distance away from the live equipment, and usually cooperates with other anti-misoperation devices such as electromagnetic locks and microcomputer five-proof lockout devices to implement forced lockout.
2.1 Cooperating use of device and electromagnetic lock
The electromagnetic lock device is connected to the high voltage live display lock device through a lock input interface. It is forced to lock when the high voltage equipment is energized, and it is allowed to be manually unlocked when there is no power. The lock lever can block the operating hole, button or cabinet door to achieve its locking function, lock There is usually no interaction force relationship between the rod and the locked device. For example, when the cabinet door is locked, as shown in Figure 3, the closing function of the door still relies on the original lock. The electromagnetic lock device is installed on the door frame, and the locking rod blocks When the door is opened, the locking lever will have a powerful effect on the door only when it is illegally operated.
2. 2 device for electrical lockout
The high-voltage live display device can output a latching contact (moving and closing contact K, as shown in Figure 4) according to the live condition of the high-voltage equipment to the control circuit of the electrically operated equipment (such as the grounding switch). When the high-voltage equipment is energized, The contact K is disconnected and the control circuit is blocked and cannot be operated electrically. Only when the high-voltage equipment is without electricity, the contact K is closed to meet the operating conditions. This ensures that the equipment can be operated electrically only when the high-voltage equipment is not energized.
2.3 Cooperative use of the device and the microcomputer five-proof locking device
The high-voltage live display device is used in conjunction with the microcomputer five-proof device to jointly complete the electrical inspection operation when the grounding switch is closed on the line side or the temporary grounding wire is hung. When the line has electricity, the device outputs a latching contact to tell the microcomputer that the five-defense device line has electricity and cannot be operated. When the three phases of the circuit are not energized, the device allows the operation light to be on and the contacts are closed. At this time, the computer key is inserted into the electroscope to form a loop, so that the computer key detects that there is current, indicating that the circuit has no voltage and can be operated. As shown in Figure 5 below.
The application of the high-voltage live display device effectively avoids the occurrence of misoperation accidents and effectively ensures the power system. Here are a few suggestions:
(1) For the designer, the relevant requirements must be met during design, so that the products of different manufacturers are unified and compatible with each other.
(2) For users, it is important to summarize the problems that occur during the use of high-voltage live display devices. It is very important to check the quality of the product, and sensor failure is a common problem.
(3) During the indirect electrical test, if the high-voltage live display device is suspected to be faulty, it cannot be unlocked blindly, and the relevant unlocking regulations must be strictly followed.