Mrt Detector - China

Fig.

3 LMA Magnetic bridge circuit

MTC testing method based on model considers testing to process and testing instrument to be system.

According to the designated importation of tested object and the testing instrument itself (namely, fore experience knowledge) and the data gained with many experiments (namely, later experience knowledge) self-particular mathematical model of testing instrument setup.

Through data processing with relative calculus, it may get accurate overall descriptor on the testing results of the tested object.

2 - The available bases and existing problems for electrical elevator testing wire rope

2.1 Bases

According to “The safety Norm for the Electrical Elevator Manufacture and Assemblage” (State standard GB7588)

Shanghai formulate the local standard for “The safety Norm for the Electrical Elevator Maintenance” (OB31/193) specially:

Reporting as unserviceable stipulation for electrical elevator wire rope.

a) The wire rope arise from broken ply;

b)The active diameter that created by the abrasion loss or corrosion of single wire in the wire rope is 90% of the original diameter at that time.

;

c) It is stipulated that a hank of span length for wire rope (namely, a pitch) attain the following form broken wire number at that time.

；

Reporting as unserviceable single wire broken wire number form

Wire rope assurance coefficient

n When it is within a pitch existing following broken wire rope number the wire rope must be discarded as useless promptly The abrasion loss or corrosion of wire rope surface attain the percentage (%) of the original wire rope diameter 0 10% 15% 20% 25 30%

0—10 16 13 12 11 9 8

10—12 18 15 13 12 10 9

12—14 20 17 15 14 12 10

14—16 22 18 16 15 13 11 Fig.

4　Magnetizing characteristic curve for wire rope

Independent single piece of wire rope testing can acquire the satisfactory results with choosing the permanent magnets of the proper number, utilizing the fork form pole terminal, according to the structure of the wire rope, or adopting single of multi circuit excitation in the radial direction.

As shown Fig 4 - With regard to 6×19 round strand wire rope of structure, at that time, the intensity of magnetization for the wire rope is 3-4×103 A/M.

So long as you try to make it at the moment when the wire rope passing through the sensor to attain the magnetizing approaching saturated zone, you can get the satisfactory result.

According to experience we know the permanent magnets in the sensor would provide enough intensity exciting field and can make the intercity of magnetization attaining 4~5×103 A/M concentrically in the wire rope testing for electrical elevator.

There fore, adopt magnets paralleling, circumference equal distribution, multipoint polar pillar installation, thus form compound exciting, circuit.

The polar pillar arrangement of magnets must be avoided, the closing of magnetic

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