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ME60 Troubleshooting Guide V1.0 (VRPv8)

This document provides the maintenance guide of the device, including daily maintenance, emergence maintenance, and typical troubleshooting.
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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Grounding System Maintenance

Grounding System Maintenance

How to maintain the grounding system.

Checking the Grounding System

To maintain the grounding system, check the following:

  • The electrical contact between the metallic parts and the cabinet body. The metallic parts and the cabinet body must be well contacted. The contact points such as screw holes, guide lanes, and lifting ears must not be painted. Otherwise, bad electrical contact may occur.

  • The grounding terminals at the front and back doors and the side doors. These terminals must be well connected with the grounding wires.

  • The grounding buses of combined neighboring cabinets. If cabinets are combined, the neighboring cabinets must be connected by a grounding bus.

  • The yellow and green protecting ground cables. One end of a ground cable should connect the PGND grounding bus of the power distribution cabinet in the equipment room, and the other end connects the grounding terminal of the cabinet. The screws that fix the ground cable should not be loose.

Measuring the Grounding Resistance

The grounding resistance of a comprehensive communication building should be no more than 1 Ω; that of a common communication station, no more than 5 Ω; that of the place with high earth resistibility, no more than 10 Ω.

To measure the grounding resistance, use an earth resistance tester. Figure 2-1 shows the arrangement of the probes of an earth resistance tester.

Figure 2-1 Arrangement of probes of an earth resistance tester

  • If the distance between the current probe and the rim of a grounding net is d1 and the length of the maximum diagonal line of a grounding net is D: d1 is normally four to five times as much as D.

  • If the distance between the probe and the side of a grounding net is d2, then d2 is 50% to 60% of d1.

  • In measurement, move the voltage probe along the line connecting the grounding net and the current probe for three times; each movement is about 5% of d1. If the three resistance values are similar, it means that the grounding resistance is normal.

  • Position the current probe and the voltage probe in a manner that is perpendicular to the wires of a grounding net or underground metallic pipes.

  • Do not measure the grounding resistance right after a rain.

NOTE:

If you feel difficult to measure d1, you can take 2D instead of d1, D instead of d2, in a place where the earth resistibility is uniform. In a place where the resistibility is not uniform, you can take 3D instead of d1, 1.7D instead of d2 as the data.

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Updated: 2019-06-11

Document ID: EDOC1000175918

Views: 13662

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