Analysis and Countermeasures of potential safety hazards of desulfurization electrical system
the desulfurization electrical system of a plant is mainly composed of 6kV system, 380V system, DC system, ups and standby power supply
the power supply of desulfurization 6kvv section and 6kvvvi section is respectively connected by the corresponding working 6kvv section of unit 5 and unit 6 and the working sections a and B of 6kvvvi section. The 6kV load in the desulfurization island is tapped on various bars such as desulfurization 6kvv section and 6kvvvi section rib steel for tensile test; Universal tensile testing machine, round sample jaw 26 (4) 0mm1 pair, suitable for tensile tests of round steel, ribbed steel and other bars with a diameter of 26 (4) 0mm; Up
380/220v system adopts PC (power center) and MCC (motor control center) two-level power supply mode. Motor circuits of 75kW and above, all MCC power circuits and class I motors are powered by PC, other loads are powered by the nearest MCC, and lighting and maintenance circuits are connected to the local MCC. Two desulfurization low-voltage working transformers (1600KVA) are tapped on the corresponding desulfurization 6kvv section and 6kvvvi section of each unit, and the power supply is mutually standby
each unit desulfurization device is equipped with a section of 380/220v desulfurization security MCC, the working power supply is from the 380/220v desulfurization PC section of each unit, and the standby power supply is from the security PC section of the unit. The switching between power supplies adopts the double power supply automatic switching device, which is powered by the desulfurization PC section in normal times and automatically switched to the security power supply of the main plant in case of accident, and the two power supplies are locked mutually
the desulfurization system of two units share a set of 110V DC system, and the DC system adopts single bus sectional wiring. The DC device adopts two-way AC power supply, and the power supply is respectively from the desulfurization security section of desulfurization #5 and #6 units of the unit. The DC system ensures that all loads will continue to operate at rated voltage for not less than 1 hour after the power failure of the whole plant. You accepted my invitation
the desulfurization system of the two units is equipped with a set of 30KVA AC uninterruptible power supply system (UPS), which mainly supplies power to the desulfurization DCS control system, desulfurization instruments and other loads. After the power failure of the whole plant, ups will continue to maintain all its loads under the rated voltage for no less than 30 minutes
the electrical system and desulfurization DCs are controlled by hard wiring
II. Analysis of potential safety hazards of desulfurization electrical system
in the auxiliary control operation of the desulfurization system in our plant, there are many electrical equipment and high voltage levels, and its potential safety hazards are mainly composed of potential safety hazards of electrical equipment and system itself, potential safety hazards of switching operation, etc. The equipment and system itself have the following problems:
1 The mechanical locking jam of desulfurization 6kV switch is common, which brings great inconvenience to the switching operation of operators
2. The desulfurization 6kV switch has no double number, which is very easy to go wrong and cause major safety accidents.
3. There is no special tool cabinet in the desulfurization 6kV room. There is no quantity of all tools, so it is not conducive to safety management
4. The design load of desulfurization security section is too much, which may affect the host when the working power supply is disconnected
5. The electrical design of some equipment is unreasonable. If the service station of booster fan does not pay attention to quality and long-term benefits, it can not but sacrifice product quality to achieve only one-way power supply. The original design was MCC connection, and then it was changed to security section connection considering safety. The cooling fan of booster fan is also an important equipment, but it is only connected on MCC section
6. At present, the GGH main motor and auxiliary motor of the same boiler are connected by the same security section. In consideration of safety, they should be connected separately. If the main motor is in #5 desulfurization security section, the auxiliary motor should be changed to #6 desulfurization security section
7. Most of the cabinet doors at the wiring terminals of many switchgear cabinets, especially 380V cabinets, are open, which has potential safety hazards. They should be closed when they are not operated
8. In the absence of operation or maintenance personnel, the door of the power distribution room of the desulfurization electric control building should be closed to prevent miscellaneous personnel from entering and avoid potential safety hazards
9 The emergency lighting of desulfurization system has never been tested, and it is preliminarily judged that the automatic switch is jammed and cannot be switched.
10. Some equipment, such as desulfurization baffle sealing fan switch cable of #3 unit, was not wrapped after removal, and the cable was exposed
11. The power output frequency of desulfurization UPS system is low (49.5hz), which has potential safety hazards.
12. Some signboards of desulfurization electrical system are not hung, and the cable direction is unclear.