eSpace IAD
Troubleshooting
3 Co mmon Troubleshooting Methods
Issue 02 (2012-02-29)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
91
Ground Bar Is Not Installed in the Equipment Room, but the Ground Electrode
Can Be Buried Nearby
When no ground bar is installed in the equipment room, and the ground electrode can be
buried nearby, use an angle steel or steel pipe not shorter than 0.5 m. Bury the angle steel or
steel pipe directly in the earth. The cross-sectional area of the angle steel should not be less
than L x W x H = 50 x 50 x 5 (mm
2
), and the steel pipe should not be thinner than 3.5 mm.
The material used should be steel plated with zinc. Weld the yellow -green PGND cable of the
device with the angle steel. Paint the surface of the welding point with anti-rustic paint. The
cross-sectional area of the PGND cable must not be less than 4 mm
2
, and the PGND cable
should be as short as possible. Do not wind the cable. See
Figure 3-24
Grounding diagram when the ground electrode can be buried nearby
Ground Impedance Requirements
The ground impedance of an equipment room is determined by the equipment room
environment. The ground impedance of a central equipment room must comply with standard
YDJ26-89 (less than 1 ohm); that of a common equipment room must be less than 5 ohms;
that of angle steel buried in the earth must be less than 10 ohms. In the area with high soil
impedance ratio, spray some salt water or impedance-reducing agents to the earth.
Table 3-8
Common device ground specifications
No.
Specifications
1
The design for ground must follow the principle of equal voltage and equal
electric potential. That is, the working ground and protection ground (including
the shielded ground and the lightning-proof ground of the cable distribution
frame) are jointly grounded in the same group of ground electrodes.
2
The cable tray, rack or shell, metal ventilation pipe, and metal door or window
in the equipment room must be grounded for protection.
3
The metal device parts that are neutral in normal conditions must be grounded
for protection.
4
The ground cable must be connected properly to the protection ground bar of
the equipment room.
