256HC Mast Section paid attention to in the construction of tower crane electrical system
1. The tower crane cable is not allowed to walk on the ground. A cable drum with a tensioning device shall be installed. The cable shall be automatically wound along with the tower crane traveling drum to prevent the cable from friction with the sleeper or being wound by debris on the track.
2. The safe distance between the overhead line and the tower crane at the construction site shall be in accordance with the provisions of the temporary electricity Code: "the minimum horizontal distance between any part of the rotating boom crane or the side line of the overhead line below 10kV at the edge of the hoisted object shall not be less than 2m. "When the distance is less than this, the protective frame shall be erected as required, and 36V Color Bubble (or red light bulb) shall be provided during night construction. When the crane operation radius passes over the overhead line, protective measures shall also be provided above the line.
3. For the repeated grounding of tower crane, a group shall be set at both ends of the track. For the longer track, another group of grounding device shall be added every 30m. The steel bar or flat iron shall be used as the circular electrical connection between the two tracks, and the wire shall be used to form the electrical connection at the joint between the tracks.
4. The protection neutral and grounding wire of tower crane must be separated. The power line can be sent to the distribution box at the rail end of the tower crane, from which the PE line is led out and connected with the repeated grounding wire of the rail, that is, the equivalent PE line is connected with the equipment shell through the rail wheel.
5. When TT system is adopted on site, tower crane shall be grounded with resistance no more than 4 Ω; when TN system is adopted, in addition to protection and neutral connection, repeated grounding shall be carried out according to temporary power use specification, with resistance no more than 10 Ω.
