The utility model relates to a bus power supply quick protection cabinet
backdrop
There are many main causes of shock, including lightning strikes, voltage fluctuations of the external network and short circuit fault, as well as human factors such as unbalanced load starting and plant power switching. According to statistics, the voltage drop caused by lightning strikes accounts for more than 60%. Because of the chance and unpredictability of voltage sag, it can be said that voltage sag is inevitable. The phenomenon caused by external power grid, internal failure and other reasons will affect the reliability of power grid power supply, resulting in sensitive loads such as a large number of contactors, frequency converters, PLC, various digital equipment tripping or damage, and easy to cause computer information loss, crash, which may lead to the interruption of process production, causing significant economic losses to enterprises. It even affects the safe and stable operation of enterprises.
According to the existing protection configuration, when a ground fault occurs, the detection time of the protection device is about 60ms, the circuit breaker trip time of the conventional spring operating mechanism is 60ms, and the voltage dip duration is at least 120ms. Although the duration of the voltage dip is short, the consequences are very serious, and the specific hazards are as follows:
When the voltage drops below 70% of the rated value, when the duration is more than 1 cycle, the contactor will trip causing a large area of power failure for the user, for a class of users, the loss caused by sudden power failure is very huge.
When the voltage is reduced to less than 50%, the motor loses magnetism, and the motor starts repeatedly when the voltage recovers, especially for users with more high-voltage motors, many motors accelerate at the same time, causing a great impact on the power grid, and in severe cases, causing power grid outage.
For programmable controller (PLC), when the voltage is lower than 50%, PLC will stop working; Some I/0 devices, when the voltage is less than 90%, the duration of only a few cycles will be cut. This will lead to the use of PLC production line operation interruption, resulting in significant economic losses.
Voltage dip can cause server breakdown and data loss, which has a significant impact on information security.
Considering that the voltage sag problem has brought serious power safety risks to the power grid and enterprise users, Nanjing Guogao Electric Automation Co., Ltd. developed FBVP series of busbar voltage current limiting protection equipment based on rapid fault detection and rapid mechanical switch, which mainly solves the problem of shimmying caused by short circuit fault of branch lines in the area. Detection time is less than 5ms, quickly break the fast mechanical switch, input impedance, limit short circuit current, stabilize the voltage drop of the upper bus, so as to ensure the voltage stability of all the upper bus lines, stable voltage of at least 90%, shorten the duration of power grid shaking, reduce the power grid, enterprise important load power supply interruption and shutdown possibility, Provide stable and reliable power supply for enterprise production.
Scheme content
This series of products mainly solve the problem of voltage dip caused by short circuit of the line, the existing solution has a long detection time, the circuit breaker equipment has a long opening and closing time, resulting in a long voltage dip, and the important load on the grid has the risk of shutdown.
Bus quick protection equipment can be configured in feeder branches prone to short circuit fault. When a temporary short circuit fault occurs on the feeder side, resulting in a sharp drop in the bus voltage, the parent protection equipment will quickly identify the line fault, the parent protection device will send tripping instructions to the fast switch, the current limiting reactor will be put in, and the fault current will be limited. The bus voltage will be maintained at more than 90% of the rated voltage, so as to achieve the protection of the upper bus voltage. When the lower-level fault is removed, the parent device overlaps and the system returns to normal operation. When the lower fault cannot be cleared normally, the backup conventional circuit breaker in the mother cabinet will trip to isolate the fault point.