The design work of 436 and the first item is as follows: civil engineering carries out equipment basic design; process, automation, power supply, waterway, heating and ventilation design work. Subsequently, the basic drawings of the equipment were sent to the site one after another, such as: air separation tower foundation, air compressor foundation, oxygen and nitrogen compressor foundation, air cooling tower foundation drawings, etc., from large to small. 46 civil construction units began construction equipment foundation.
At the same time, the design of 416 and the first item is: civil construction platform, trench, pipe network support, embedded parts, opening and opening, workshop wall design. Process, automation, power supply, waterway, heating and ventilation design work has been more than half, followed by civil construction platform, trench, bracket and other drawings. The 456 field equipment foundation has been constructed and the installation unit began to install the equipment. Such as: air compressor, oxygen and nitrogen pressure machine, air separation tower, expander, air cooling tower, water pump, freezer and so on. Electric and instrument control began to install such as: electric control cabinet, instrument panel, transformer. At the same time, the installation and production work of the spherical tank is carried out. At the same time as the fifth work, the construction of the workshop wall, doors and windows, trenches, pipe network and pipe supports shall be carried out.
4B6 and the fifth item are simultaneously crossed to carry out the pipeline laying of the process, the instrument, the cable trough and the threading pipe. First, air compressor, pre-cooling, purification, air separation tower system, liquid oxygen emission system process, instrumentation, power supply pipeline laying. Then, the process pipeline is pressed, purged, equipment commissioned, pipeline painted, bare cold and so on.
426 and the second item simultaneously carry out the oxygen and nitrogen press system; the liquid oxygen storage vaporization filling system; the ball tank area system; the pipe laying of the pipe network inside and outside the station; the pressing, flaw detection, purging, equipment debugging, pipeline painting, etc. jobs. 4806 performs the overall linkage with load test, and sends oxygen and nitrogen to the user.
4886 and the 80th item are simultaneously laid in the station area. When the purity and output of oxygen and nitrogen products reach the design standard, the entire oxygen station has the conditions for completion acceptance. The whole project began to work on the construction drawing design from August 8, 2008. On August 10, 2008, the civil construction broke ground, and the equipment installation began on January 1, 00. On February 85, 00, all the Page2 metallurgical power was installed. The wiring is correct. Everything is fine after the device is put into operation.
The cause analysis of the accident was confirmed by on-site inspection to confirm that the cause of the accident was that when the 456 line cabinet was rebuilt and installed, the 20007 current transformer was in the shape of a ring, and there was no attention to the polarity problem when the busbar was set, resulting in the pole of the differential protection. The wrong connection is as shown.
Figure Differential protection wiring polarity diagram But under normal load, why does differential protection not work? Because under normal load conditions, the load current is 8009 and then converted to the secondary side 417007908, 800 load current after 20007 current transformer is converted It is 8007200079, which is far less than the operating current AB980 of the differential relay setting, and therefore does not operate. However, in the case of an accident, such as short circuit faults in oxygen production, experience calculation, three-phase short-circuit current CDE913CFG9H18H3, so in the case of short circuit, the total current is H18HI8009188H.
K2L should respond to the secondary circuit adjustment test of differential protection in our annual equipment inspection. In the routine maintenance work, the secondary circuit of differential protection should be inspected regularly to ensure the safe operation of the equipment.
Brush Machine Components,Brush Machine Accessories,Brush Machine Parts,Brush Machine Spare Parts
Yangzhou Haixing CNC Brush Machine Co., Ltd. , http://www.brushmachine.nl