TB/T 2640-1995Structural Design for Fire Protection of Passenger Train (English PDF)

3.1 Terms

The following terms and definitions apply to this document.

3.1.1

Lightning electromagnetic impulse

3.1.13

Cable entrance earthing bar

A dedicated earthing bar connecting the cable steel jacket entering into the

machine room to the general earthing bar or ring grounding electrode at the

entrance.

3.1.14

Lightning equipotential bonding

To reduce the potential difference created by lightning current, a lightning

protection measure that connects the isolated conductive components

directly to the lightning protection system either directly or through a surge

protector.

3.1.15

Lightning protection device

Equipment used to limit lightning transient overvoltage AND to shunt

lightning surge currents.

3.1.16

SPD surge protective device

A lightning protection device to limit transient overvoltage AND to discharge

surge current, which contains at least one non-linear element.

Note 1. Surge protective device is also known as power protection cable,

lightning protection device, lightning protector, lightning arrester and so on.

Note 2. The surge protective device is divided into single port SPD and dual

port SPD.

3.1.17

Maximum continuous operating voltage

UC

The maximum AC voltage r.m.s. or dc voltage value that can be permanently

applied on the SPD of various protection modes.

3.1.18

3.1.23

Railway integrated earthing technology

A grounding system which connects the traction power supply, power supply,

signal and communication systems, buildings, road beds, platforms, bridges,

tunnels, sound barriers, etc., along the railway which require grounding

through the common earthing system.

3.1.24

Through-railway grounding wire

Grounding electrode laid along the railway to connect all kinds of equipment

and facilities, AND used as the auxiliary passage for the traction backflow.

3.2 Abbreviations

The following abbreviations apply to this standard.

CEEB. Cable Entrance Earthing Bar

EMC. Electro Magnetic Compatibility

ERP. Earthing Reference Point

LEMP. Lightning Electromagnetic impulse

LP. Lightning Protection

LPS. Lightning Protection System

LPZ. Lightning Protection Zone

PE. Protective Earthing

SPD. Surge Protection Device

SPM. Surge Protection Measure

a) External areas (the area outside the building in which the machine room

is directly exposed to the threat of thunder and lightning).

LPZ0. In this zone, the threat comes from an un-attenuated lightning

electromagnetic field. The system inside the machine room may suffer the

risk of all or part of the lightning surge current. LPZ0 is further divided into

the following two categories.

LPZ0A. Direct lightning non-protection zone, it is the space that can

withstand the direct lightning and the entire lightning electromagnetic field,

the internal system may suffer all the lightning surge current hazards.

LPZ0B. Direct lightning protection zone, it is a space that protects the direct

lightning BUT still can suffer all the lightning electromagnetic field. Internal

systems may suffer the hazards of some lightning surge currents.

b) Internal area (the area inside the building in which the machine room is

not directly exposed to the threat of thunder and lightning), there may be

multi-layer zoning.

LPZ1. The lightning surge current in this zone is limited by the on-boundary

shunt and SPD. Space shielding can attenuate lightning electromagnetic

field.

LPZ2... n. The lightning surge in the circuit is further shunted at the

boundary and limited by the SPD on the boundary, the lightning

electromagnetic field is further attenuated by the boundary space shielding.

4.5 The signal room shall be integrated into the machine room building

synthetical protection system. As for the signaling equipment in the interval and

station which is exposed to the lightning environment, it shall take the following

lightning protection measures.

a) The signaling equipment shall be placed in the chamber and box with the

shield grounded;

b) The cable shielding leading into the machine room shall be grounded;

c) Cable and equipment interface are reasonably equipped with SPD or other

lightning protection equipment;

d) The conventional arresting device is provided at the location where the

signaling equipment is concentrated, to include the signaling equipment

into the direct lightning protection scope.

5.1 Lightning risk factors of signaling equipment

The lightning risk of railway signaling equipment is related to the following

factors.

a) The meteorological conditions such as lightning parameters along the

railway line and the location of the station and machine room;

b) Topography and geology of the area where the protected building is

located;

c) Characteristics and surroundings of signal room buildings or groups of

buildings, structures (brick, reinforced concrete, steel frame, metal facade,

etc.), building dimensions (length, width, height and location distribution),

types of roofing materials, height of the adjacent building;

d) Distribution of electronic information system equipment on all floors in the

building;

e) The type, function and performance parameters (such as working

frequency, power, working level, transmission rate, characteristic

impedance, transmission medium and interface type) of the protected

equipment in the signal room, the structure of the communication network,

the electrical connection and signal transmission method between

different equipment, lightning withstanding capacity Uw at each port, etc.;

f) Power supply and distribution, AND the grounding type of power

distribution system.

The above factors shall be considered before taking the synthetical lightning

protection measures for railway signaling equipment.

5.2 Signal room location selection

5.2.1 When the signal room is set up separately, the signal r...

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