Intelligent field of surge protector solutions experts
The electromechanical system of expressway is characterized by many points, wide area and long lines. There are not only strong current equipment, but also a large number of monitoring, communication, sensing and other weak current equipment. There are often prominent equipment points in open areas, power lines often have to cross mountains, and transmission and control lines often cross complex geological layers. These are vulnerable to lightning strikes or lightning induction. Therefore, it is necessary to strengthen the lightning protection of electromechanical system of expressway.
The lightning protection of expressway electromechanical system is mainly divided into two parts
Direct lightning protection+lightning electromagnetic pulse protection, as follows:
1. Direct lightning protection
1.1 The electromechanical system shall be located in the direct lightning protection zone (LPZ0B). The height of the lightning rod of the second class lightning protection buildings (structures) shall be calculated and determined according to the 45m ball radius? When air termination net is used, the grid size shall not be greater than 10m × 10m or 12m × 8ｍ。 The height of lightning rod of Class III lightning protection buildings (structures) shall be calculated and determined according to 60m ball radius? When air termination net is used, the grid size shall not be greater than 20m × 20m or 24m × 16ｍ。 It is better to use metal rods, steel bars in columns or vertical metal frames as natural downlead. When there is no metal rods, steel bars in columns or vertical metal frames available, special downlead and grounding devices should be set up. The value of impulse grounding resistance should not be greater than 10 Ω. See Appendix C of GB50057-2010 for conversion of impulse grounding resistance and power frequency grounding resistance and determination of effective length of long-distance grounding
1.2 The steel structure of the toll shed should be used as the lightning arrester and downlead, and its foundation reinforcement mesh should be used as the common grounding device. The grounding resistance value should comply with the provisions of 4.3.6 in GB50057-2010, and should not be greater than the grounding resistance value determined according to personal safety.
The metal poles of lighting lamps and cameras in the toll plaza should be used as lightning rods, and the impact grounding resistance of the metal pole's foundation grounding should not be greater than 10 Ω. In the position where people pass or may stay, it is necessary to? Take the following measures to prevent step voltage, contact voltage and side flashover:
a) Anti step voltage shall meet one of the following requirements:
The resistivity of soil surface layer within 3m of downlead shall not be less than 50k Ω m. Or lay 5cm thick asphalt layer or 15cm thick gravel layer;
Use mesh grounding device to equalize the ground potential;
Use guardrails and warning signs to minimize the possibility of people entering the ground within 3m from the downlead.
b) The protection against contact voltage and side flashover shall comply with one of the following provisions:
The resistivity of surface layer within 3m of downlead shall not be less than 50k Ω m, or 5cm thick asphalt layer or 15cm thick gravel layer shall be laid;
Exposed downlead whose conductor is less than 2.7m above the ground is 1.2 ／ 50 μ S Insulating layer with impulse voltage of 100KV or cross-linked polyethylene layer with thickness of at least 3mm;
Use guardrails and warning signs to minimize the possibility of people contacting downlead.
1.3 The control room, communication room, substation and other buildings (structures) of reinforced concrete structure should be equipped with exposed lightning protection net. The reinforcement in the column is used as the natural downlead, and the foundation reinforcement net is used as the common grounding device. The grounding resistance shall comply with the provisions of 4.3.6 in GB50057-2010, and shall not be greater than the grounding resistance value determined according to personal safety.
1.4 The lightning protection grounding of the lightning arrester installed on the top of the toll shed shall be connected with the foundation grounding of the toll plaza to form a common grounding system.
2. Lightning electromagnetic pulse protection
a) Equipotential bonding
b) Magnetic shielding
c) Isolation interface
d) Surge protective device (SPD)
2.1 Lightning protection measures for electromechanical system along the line
2.1.1 Lightning protection of monitoring system
Class D SPD is set at the power incoming terminal of the distribution box in the monitoring center (sub center) room.
The incoming line terminal of the distribution box of the field monitoring equipment along the line, Class B SPD shall be set in the strong lightning area and the multi lightning area, Class C SPD shall be set in the medium lightning area, and Class D SPD shall be set in the less lightning area.
At the incoming line end of Ethernet signal interface or data signal interface or video signal interface of various outfield monitoring equipment, Class E SPD shall be set in strong lightning area and multi lightning area, and Class F SPD shall be set in medium lightning area and few lightning area.
2.1.2 Lightning protection of toll system
The general incoming line terminal of the power supply room of the toll station, the outgoing line terminal of the outdoor monitoring equipment of the power supply room, the outgoing line terminal of the charging UPS power supply of the power supply room, the incoming line terminal of the distribution box in the toll plaza, the incoming line terminal of the camera power supply in the toll plaza, the strong lightning area and the heavy lightning area are equipped with Class B SPDs, the medium lightning area is equipped with Class C SPDs, and the low lightning area is equipped with Class D SPDs.
Class D SPD shall be set at the incoming line terminal of industrial personal computer power supply and toll metering power supply in the toll lane.
Class E SPD shall be set at the data signal incoming terminal of the weighing equipment of the toll collection system, the data signal incoming terminal of the ETC fee amount display, the camera Ethernet or video control signal incoming terminal of the toll plaza, the heavy and heavy thunderstorm areas, and Class F SPD shall be set at the medium and low thunderstorm areas.
Lightning protection of communication system
Class D SPD is set at the incoming line end of power supply in the communication machine room.
At the incoming line end of the equipment of Ethernet signal interface, Class E SPD shall be set in strong lightning area and multi lightning area, and Class F SPD shall be set in medium lightning area and few lightning area.
2.1.2 Lightning protection of power supply and distribution system
Manage the low-voltage incoming terminals of the general (sub) center power distribution room, toll station power distribution room, service area power distribution room, parking area power distribution room or various box type substations, set Class A SPD in the strong lightning area and the multi lightning area, set Class C SPD in the medium lightning area, and set Class D SPD in the less lightning area.
Class D SPD is set at the power incoming terminal of the capacitance compensation cabinet.
2.2 Lightning protection measures for tunnel electromechanical system
2.2.1 Lightning protection of monitoring system
The incoming line terminal of the power supply of the outdoor monitoring equipment distribution box outside the tunnel and the first monitoring distribution box inside the tunnel, the Class B SPD, the Class C SPD and the Class D SPD are set in the strong lightning area and the multi lightning area. Class D SPD is set at the power inlet end of the second and subsequent monitoring distribution box in the tunnel.
At the incoming line end of Ethernet signal interface or data signal interface or video signal interface of various outfield monitoring equipment, Class E SPD shall be set in strong lightning area and multi lightning area, and Class F SPD shall be set in medium lightning area and few lightning area.
2.2.2 Lightning protection of power supply and distribution system
Class B SPD is set at the low-voltage incoming line terminal of the incoming line cabinet, dual power distribution cabinet and the incoming line cabinet of the tunnel buried transformer in the tunnel substation, in the strong lightning area and the multi lightning area, Class C SPD is set in the medium lightning area, and Class D SPD is set in the less lightning area.
At the inlet and outlet terminals of UPS cabinet and EPS cabinet in the tunnel substation, Category B SPD is set in the strong lightning area and the multi lightning area, Category C SPD is set in the medium lightning area, and Category D SPD is set in the less lightning area.
Class D SPD is set at the incoming line end of the capacitance compensation cabinet of the tunnel substation.
At the inlet end of the first distribution box (cabinet) and control cabinet in the tunnel, Class B SPD is set in the strong lightning area and the heavily mined area, Class C SPD is set in the moderately mined area, and Class D SPD is set in the less mined area. The second and later distribution box (cabinet), control cabinet and tunnel substation capacitance compensation cabinet inlet terminals in the tunnel are equipped with Class D SPD.
