Why is the motor lead wire fixed so important?
The motor lead wire is the key component to realize the connection between the motor and the power supply. According to the rated voltage of the motor, the rated motor and the use environment, etc., the conductive area, insulation structure, heat resistance and corrosion resistance of the motor lead wire are made. Provisions.
Some motor lead wires are connected after the windings are dipped, and some manufacturers complete the connection before the windings are immersed, and are dipped together with the windings. Different production and processing processes have different requirements for the lead wires. With the winding dipping process together, the requirements for the lead wires are relatively high. The lead wires must be able to withstand the corrosion of the insulating paint at a certain temperature.
In addition, the lead-out leads from the base and the fixing in the inner cavity of the machine are very important quality control requirements. For example, at the exit of the lead wire, there must be insulation protection to prevent the damage of the lead wire. When the inner cavity of the seat passes, the lead wire should be reliably fixed to prevent vibration caused by the motor running, causing the lead wire to be damaged and causing electrical failure.
Standard interpretation of the provisions of the motor lead wire
GB14711 is a general safety requirement for small and medium-sized motors, and specifies the safety performance of motor lead wires.
1. Basic regulations
If the motor has a power cord (that is, the lead wire we often say), or to facilitate connection with other equipment, provide a lead cable that extends out of the motor base, and a plug for connecting the power line when needed. Such cords and plugs shall comply with the relevant standards of the product or shall comply with the requirements for cords in the relevant standards of such equipment. This requirement includes the conductive area of the cable, the insulation structure, the voltage rating, the corrosion resistance, and the performance and dimensional requirements of the end fittings connected thereto.
2. Grounding requirements
The standard states that there should be a grounding conductor in these cords unless grounding is not required. The lead wire (including the end) used for grounding should have different colors or marks for easy distinction, and of course other requirements for the grounding wire, such as the cross-sectional area, and the diameter of the grounding bolt.
3. Voltage level requirements
The rated voltage of the motor lead flexible cable shall not be lower than the maximum working voltage of the motor, and its current carrying capacity shall be at least equal to the load current of the use factor or the full load rated current of 125%, taking a larger current. This article requires that the conductive section and working voltage of the motor connection wire be specified at the same time; the standard provisions of the cable insulation should be able to withstand the power frequency withstand voltage test of the circuit.
4. Fixing and protection requirements for lead wires
The standard stipulates that, in addition to the measures to eliminate the possibility of pulling force, or the lead cable is not exposed to the motor, an insulating protective layer and clamping device shall be provided at the exit of the flexible cable to prevent external tension from being transmitted to the internal wiring and preventing the flexible cable ( Power cord) Rotation or displacement causes an accident. This requirement is not effective in many motor factories, and the resulting electrical faults are everywhere. The standard also stipulates that measures should be taken to prevent the lead cable from retreating into the motor. This is also a fixed and limit problem for the motor lead wires.
5. Insulation and strength requirements of the fixture
The clamping device for clamping and fixing the lead flexible cable is made of insulating material. If metal material is used, there should be an insulating lining to prevent the lead insulation from being damaged due to grounding damage. The clamping device for the flexible cable shall be capable of being damaged by the specified tensile and torsion tests.
6. Requirements for line space
The lead flexible cable should not pass rigidly through the incoming hole to prevent insulation damage. This is the detail of the motor design and the focus of the apparent quality control of the parts in the manufacturing process.
7. Wiring requirements in the junction box
In the motor terminal box, the loose lead cable for field wiring shall have a free length of at least 150 mm. This requirement is not well controlled in the production process of the motor. In most cases, the performance is short. Once the quality of the terminal is generated during the motor running process, the connection and fixing cannot be completed again.
Reprinted from the network