Operation Environment Requirements. Layout of Equipment Room. Lightening Protection and Grounding Requirements, страница 10

The designed anti-earthquake intensity of the telecom equipment room must be one degree (Richter scale) higher than that for the common buildings. The equipment room building that cannot meet the requirement should be reinforced. When installing the OptiX optical transmission equipment, the following anti-earthquake measures should be taken.

n  Use steel framework for the cabinet of the OptiX OSN 9500. There are locking devices to fix the boards in the cabinet.

n  The cabinet is reinforced with slide rail on the top and supports at the bottom.

5.  Lightning protection

Chimneys, antennae or other things that are over 15m tall on the top of the equipment room building should be designed according to the lightning protection requirements for civil buildings.

Measures should be taken against direct flash and intrusion of lightning current. In the main high-rise transmission building, protective measures should be taken to prevent side lightning strokes, especially in frequent lightning areas. Therefore designers should take actual conditions into consideration and take appropriate measures. For example, connect the metal external window frame to the lightning protection wire; along the height of the building, place the lightning protection metal bands at a definite spacing on the outside wall, etc.

The main equipment-room building should be provided with the following lightning protection measures:

n  The building should be installed with lightning arrester nets or bands at the positions susceptible to lightning strokes. Lightning prevention wires or lightning rods should be installed on the top of chimneys and antennas that are protruding from the building. The cross-sectional area of the grounding wire of the lightning protection device should not be smaller than 2 mm2, while the space between the wires not larger than 30 m.

n  The grounding resistance of lightning protection grounding device for the telecom building should not be greater than 10 W.

n  Outdoor cables and metal pipes should be grounded before entering the building, and the outdoor overhead cables should be equipped with lightening protection devices at the inlet of the building.

n  It is suggested to use roof plates, beams and pillars made of reinforced concrete, and the reinforcement bar as the ground wires of lightening arresters.

In the past lightning protection grounding of the building was separate from the grounding for telecom system and power supply system, and a large distance was required between the grounding objects. However, the distance requirement is not satisfied due to small space of the building. In fact, they cannot be separated in most cases, so joint grounding system is recommended for the lightening protection grounding of the building. The joint grounding system shall connect the telecom BGND, PGND, lightning protection grounding of the building, and grounding of the power frequency AC power supply system. A high earth resistance of the joint grounding system is required. The earth resistance required by telecommunication is far lower than 10 W, and the grounding requirements for different telecom devices vary, so the resistance of the joint grounding system should be determined according to the minimum resistance required for the grounding device.

It is recommended to use steel bars in the walls and pillars of the building as ground wires for lightening protection. These wires should be electrically connected so as to equalize the electric potential in the building.