Where are copper and aluminum equipment clamps generally used?
There are two most common situations for selecting power equipment clamps in power design. :
1. Selection of line strain clamp when using LGJ and LJ conductors
When using LGJ or LJ wire, since the strain clamp is clamped on the outer diameter of the wire when used, the model of the strain clamp used should be selected according to the outer diameter of the wire. For example, the LGJ-185/30 wire is used in the power line. After calculation, it can be found that its outer diameter is 18.88mm. From the above table, it is known that the strain clamp should be NLL-4, NLL-5 or NLD-4.
It should be noted here that the outer diameter of the LGJ wire is calculated from the cross-section of the aluminum wire 185mm and the cross-section of the steel core 30mm. It is not simply calculated by the cross-section of the aluminum wire 185mm. LGJ wires of the same specification have different steel core cross-sections and wire outer diameters, so the strain clamps used for LGJ wires of the same specification are not necessarily the same. If it is an LJ wire, since it does not have a steel core, the cross-section of the aluminum stranded wire can be used to calculate the outer diameter of the wire.
In addition, because the tension clamp is clamped on the outer diameter of the wire, it is required to wrap the outer layer of the LGJ or LJ wire with aluminum tape during construction to prevent the wire from being damaged during crimping.
2. Selection of line strain clamp when using insulated wire
In densely populated, wooded, and polluted areas, more and more insulated wires are used instead of bare wires. Compared with bare wires, it has the advantages of higher safety and reliability, lower wire loss, and less wire corrosion. When using insulated wires, it should be noted that the strain clamp is clamped on the outer diameter of the "wire" instead of the outer diameter of the "conductor" when used, so it should be based on the outer diameter of the wire instead of the conductor To select the type of strain clamp used. For example, JKLGYJ-150/8 steel core reinforced cross-linked polyethylene insulated aerial cable is used in the power line. It is calculated that its conductor outer diameter is 15.30mm, plus its insulation thickness of 3.4mm and conductor shielding thickness 0.5mm, it can be seen that the outer diameter of its conductor is 23.1 mm. Check the above table to know that the strain clamp that should be used is NLL-5. If the equipment clamp is selected according to the conductor outer diameter 15.30mm at this time, the selected equipment clamp cannot be used.
In addition, tighten the screws evenly when installing the strain clamp. It is required that there is no increase in the wire stress at the contact surface between the wire and the metal after installation, so as to prevent damage to the wire due to breeze vibration or other wire oscillations and ensure that The grip strength of the strain clamp on the wire is not less than 95 percent of the wire breaking force.
