Lightning protection structure of hoisting equipment

Abstract

The utility model discloses a lightning protection structure of hoisting equipment. The lightning protection structure comprises a lightning arrester, a down lead and a grounding device which are connected in sequence, the grounding device is connected with the control element through a first circuit provided with a second contact switch of the relay, the control element is connected with the power source through a second circuit provided with the relay and the switch, and the second circuit is connected with the third surge protector in parallel. The control element is connected with the electronic element through a first contact switch provided with a relay, a second surge protector and a third circuit of the first surge protector. The first line, the second line and the third line are connected in parallel. The lightning protection device effectively prevents electrical components from being damaged by lightning stroke of the hoisting equipment, ensures normal operation of the equipment, and improves safety.

Description

Technical Field

[0001] This utility model relates to the field of lifting equipment, and in particular to a lightning protection structure for lifting equipment. Background Technology

[0002] Tracked cranes refer to mobile cranes that use tracked chassis. Lightning strikes occur when one part of a charged cloud discharges to another part of a cloud carrying the opposite charge, or when a charged cloud discharges to the ground. Lightning strikes damage large engineering equipment primarily through direct strikes and induced lightning. A direct strike is an electric shock caused by lightning discharging directly to the ground through the equipment. Induced lightning occurs when the electromagnetic field radiated by a direct strike causes electronic components to generate a high voltage relative to ground. Currently, there are no effective measures to prevent lightning strikes; any building on the ground (including the earth's surface) is susceptible to lightning strikes. Cranes often operate in open areas and are typically among the tallest pieces of equipment at work sites, making them prime targets for lightning strikes.

[0003] For cranes driven by hydraulic components, such as crawler cranes, there are relatively few electrical components. Small and medium-tonnage crawler cranes are not equipped with lightning protection measures. They often divert electricity through their own steel structure boom or body, and then discharge it to the ground through the base (tower crane) or track plates (crawler crane, rotary drilling rig, etc.). In the diversion and discharge process, the high contact resistance can easily cause a potential difference between the body and the ground, which in turn affects the system's voltage to ground and causes electronic components to break down and be damaged.

[0004] Even large-tonnage crawler cranes only add a DC surge protector to the power supply circuit of the core control components to prevent induced lightning strikes. Large tower cranes and crawler cranes have similar lightning protection measures, which can limit the damage of induced lightning to the power supply to a certain extent. However, if the protection circuit is incomplete, induced lightning current can enter the branch circuit through the wire conductor, causing damage to upstream or downstream electrical components or affecting signals. In summary, existing lightning protection measures for engineering equipment are rather one-sided, lacking a complete lightning protection solution.

[0005] Therefore, it is necessary to develop new lightning protection structures to prevent lightning strikes on lifting equipment from damaging electrical components and affecting the normal operation of the equipment. Utility Model Content

[0006] Purpose of the utility model: In view of the shortcomings and defects of the existing technology, this utility model provides a lightning protection structure for lifting equipment, which effectively prevents damage to electrical components caused by lightning strikes, ensures normal operation of the equipment, and improves safety.

[0007] Technical solution: This utility model discloses a lightning protection structure for lifting equipment, characterized in that it includes a lightning arrester, a down conductor, and a grounding device connected in sequence; the grounding device is connected to a control element through a circuit 1 with a relay-equipped contact switch 2; the control element is connected to a power supply through a circuit 2 with a relay and a switch; circuit 2 is connected in parallel with a surge protector 3; the control element is connected to electronic components through a circuit 3 with a relay-equipped contact switch 1, surge protector 2, and surge protector 1; circuit 1, circuit 2, and circuit 3 are connected in parallel.

[0008] The lightning arrester is a lightning rod, lightning strip, lightning protection net, or lightning protection wire, and is located at the top of the boom.

[0009] The grounding device includes a grounding structure located on the rolling wheel and a grounding structure located on the rail.

[0010] The grounding structure of the rolling wheel is a grounding brush or a grounding shoe.

[0011] The grounding structure of the rails includes a grounding cable and a grounding rod.

[0012] The electronic components are located at the head of the arm, and jumper wires are used between the arm segments.

[0013] The boom head, boom section, and boom frame are located on the lifting equipment.

[0014] Beneficial effects: Compared with the prior art, this utility model has the following significant advantages: Combining the structural characteristics of the crane itself, the proposed down conductor lightning discharge and equipotential connection can effectively discharge the powerful current generated by direct lightning strikes into the ground, while the "graded protection and step-by-step dissipation" measures can limit the lightning voltage caused by induced lightning to a safe range, thereby avoiding damage to the electrical system of the equipment by direct lightning strikes and induced lightning strikes, and ensuring the safe operation of the equipment. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0016] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0017] This utility model discloses a lightning protection structure for lifting equipment, comprising a lightning rod, a down conductor, and a grounding device connected in sequence. The grounding device is connected to a control element via a circuit 1 consisting of a relay-equipped contact switch 2. The control element is connected to a power supply via a circuit 2 consisting of a relay and a switch. Circuit 2 is connected in parallel with a surge protector 3. The control element is connected to electronic components via a circuit 3 consisting of a relay-equipped contact switch 1, a surge protector 2, and a surge protector 1. Circuits 1, 2, and 3 are connected in parallel. The lightning rod is a lightning rod, lightning strip, lightning protection network, or lightning wire, and is located at the top of the boom. The grounding device includes a grounding structure located on the rolling wheel and a grounding structure located on the rail. The grounding structure on the rolling wheel is a grounding brush or a grounding shoe. The grounding structure on the rail includes a grounding cable and a grounding rod. The electronic components are located at the boom head, and jumper wires are used between boom sections. The boom head, boom sections, and boom are located on the lifting equipment.

[0018] The present invention adopts the following solution:

[0019] 1) Measures to deal with direct lightning strikes:

[0020] Large equipment standing in open construction areas is prone to direct lightning strikes. The solution is to use lightning arresters to attract lightning from nearby thunderclouds and quickly channel the enormous energy generated by the lightning into the ground through a specific device, thereby reducing damage to equipment and personnel.

[0021] A complete lightning protection system typically consists of three parts: an air arrester, down conductors, and a grounding system. Air arresters come in various forms, commonly including lightning rods, lightning strips, lightning nets, and lightning wires. Lightning rods are generally chosen as the air arrester for cranes. However, proper grounding measures under the equipment are essential. Additional grounding brushes or grounding shoes can be installed at the structural components of the rolling wheels. The ends of the rails must be reliably connected to the grounding system at the construction site to ensure that the lightning current from the entire crane can be discharged into the ground through the rails. If the grounding system at the construction site is far from the crane, separate grounding copper rods should be installed, with the number corresponding to the number of cranes. The rails should be reliably connected to the grounding rods via grounding cables.

[0022] In addition, to reduce the potential difference between the metal conductors during a lightning strike, cable connections can be added between the joints of each structural component to maintain the equipotential bonding of the entire vehicle and ensure that the enormous energy brought by direct lightning can be successfully introduced into the ground.

[0023] 2) Measures to deal with induced lightning:

[0024] When lightning strikes a metal structure or releases enormous energy to the ground in the surrounding air, it generates powerful electromagnetic pulse waves. These electromagnetic pulse waves can cause unpredictable damage to the control systems and electrical equipment on cranes. External lightning protection methods cannot prevent the impact of electromagnetic pulse waves on cranes, so internal protection methods are also needed to prevent and suppress the hazards caused by electromagnetic pulses.

[0025] ① Install surge protectors (SPDs)

[0026] A surge protector is a special electronic device installed at the front end of the equipment requiring protection. It limits transient overvoltages and shunt surge currents, protecting components or systems from damage caused by surges. Because the electromagnetic pulse waves generated by lightning are ubiquitous, they can intrude into crane control systems and electrical equipment from all directions, especially the boom wiring. The controllers on the platform connect to the various electronic components and sensors at the boom head through junction boxes. Therefore, surge protectors should be installed according to the principle of tiered protection and gradual dissipation. This means that power surge protectors should be installed in layers along the power input lines, such as on the high-voltage side of the equipment, the secondary side of the transformer, and the low-voltage control circuit, to dissipate electromagnetic pulses and induced electromotive forces as much as possible, suppressing transient voltages within the permissible range of the equipment and protecting electrical safety. Simultaneously, signal surge protectors should be installed on electronic components, especially critical sensors and controller signal sections, to reduce the impact on control circuit signals.

[0027] SPD1 protects the sensor signal port, SPD2 protects the controller signal port, and SPD3 protects the controller power port. SPD1 and SPD2 are signal surge protectors, connected in series in the circuit to prevent damage to equipment inside the vehicle from lightning strikes that could cause damage during signal line overvoltages, and to prevent damage to signal line equipment during ground potential backflashes. They also suppress induced lightning strike overvoltages. SPD3 is a power surge protector, connected in parallel in the circuit to prevent damage to equipment inside the vehicle from lightning strikes that could cause power line overvoltages, and to prevent damage to power supply equipment during ground potential backflashes. It also suppresses induced lightning strike overvoltages. A switching power supply is used at the controller power input, and relays are used to switch multiple circuits. When the system is operating, pressing the switch activates the relay contacts, and the surge protectors protect the sensors, controller power supply, and signal ports respectively. When the system is shut down, the switch opens, and the relay contacts isolate the controller signal terminal, sensor signal terminal, sensor ground wire, and controller ground wire, preventing the formation of a loop. This method provides dual protection for the control unit and electronic components in both operating and non-operating states. For multi-signal branch protection, each branch employs the above protection method.

[0028] ② Equipotential bonding and protective grounding

[0029] Equipotential bonding reliably connects all metal components and booms of equipment using jumper wires, making them a unified whole to ensure that all parts have the same potential, eliminating potential differences. When lightning current flows through, potential differences at certain points will not cause equipment damage or endanger personal safety. Specifically for cranes, this involves connecting all metal structures, electrical control cabinets, containers, and equipment casings into an equipotential body and grounding it, thereby eliminating or reducing potential differences caused by lightning current flowing through the metal structures and equipment.

[0030] ③ Use shielded cable

[0031] The electromagnetic pulse waves from lightning have a pervasive impact on various components of equipment. Using shielded cables is one of the effective measures to reduce the effects of electromagnetic pulses. This utilizes the well-known Faraday cage principle: under equipotential conditions, the potential inside the cage is zero. Therefore, by effectively grounding the shielding layer of the shielded cable at both ends of the equipment, the path for electromagnetic pulse waves to enter the equipment through the line can be blocked, making it "impenetrable" and preventing equipment damage. Similarly, cables on cranes should be laid within metal structures or metal conduits / troughs whenever possible, and the positions and spacing of power, control, and communication cables should be rationally arranged to prevent the influence and mutual interference of electromagnetic pulse waves and induced electromotive forces.

Claims

1. A lightning protection structure for lifting equipment, characterized in that: It includes a lightning arrester, a down conductor, and a grounding device connected in sequence; the grounding device is connected to a control element through a contact switch with a relay, the control element is connected to a power supply through a relay and a switch, the switch is connected in parallel with a surge protector, and the control element is connected to electronic components through a contact switch with a relay, a surge protector, and a surge protector; the switches are connected in parallel.

2. The lightning protection structure for lifting equipment according to claim 1, characterized in that: The lightning arrester is a lightning rod, lightning strip, lightning protection net, or lightning protection wire, and is located at the top of the boom.

3. The lightning protection structure for lifting equipment according to claim 1, characterized in that: The grounding device includes a grounding structure located on the rolling wheel and a grounding structure located on the rail.

4. The lightning protection structure for lifting equipment according to claim 3, characterized in that: The grounding structure of the rolling wheel is a grounding brush or a grounding shoe.

5. The lightning protection structure for lifting equipment according to claim 3, characterized in that: The grounding structure of the rails includes grounding cables and grounding rods.

6. The lightning protection structure for lifting equipment according to claim 1, characterized in that: The electronic components are located at the head of the arm, and jumpers are used between the arm segments.

7. The lightning protection structure for lifting equipment according to claim 6, characterized in that: The boom head, boom section, and boom frame are located on the lifting equipment.

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