H3C MSR Series Troubleshooting Manual page 18

Ground resistance
Determine the ground resistance of the grounding strips according to the equipment room
environment requirements. For the central telecom equipment room, determine the ground
resistance according to YDJ26-89 (which requires the ground resistance to be smaller than 1Ω). For
non-central telecom equipment rooms, the ground resistance must be lower than 5Ω. For angle irons
hammered into the earth, the ground resistance can be relaxed appropriately to be smaller than 10Ω.
In an area with a higher ground resistance, reduce the ground resistance by using brine or resistance
reducing agent around the grounding conductor.
Commonly grounding devices
The interconnected devices must be commonly grounded and well grounded.
•
If the interconnected devices are both installed in a 19-inch cabinet, connect the grounding
cables of these devices to the grounding strip of the cabinet for common grounding.
•
If the interconnected devices are placed in the same equipment room and not far from each
other, you can join the grounding cables of the interconnected devices and then connect the
cables to the ground, as shown in
Figure 7 Common grounding for devices
•
If the interconnected devices are not in the same equipment room, make sure all
interconnected devices are well grounded.
Identifying whether the devices are commonly grounded well
As shown in
interconnected devices, and use the multimeter to measure the voltage and resistance between the
two grounding terminals.
•
If they are well grounded, the resistance between the two terminals quickly returns to zero and
the voltage is lower than 1V.
•
If they are not well grounded, the resistance between the two terminals is not zero or slowly
returns to zero, or the voltage is higher than 1V.
Figure 8, use the grounding cable to the lead out the grounding terminals of the
Figure 7.
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