Views: 0 Author: Site Editor Publish Time: 2024-07-18 Origin: Site
Since its application in lighting, there has been a classification of incandescent lamps, fluorescent lamps, iodine tungsten lamps, high-voltage mercury lamps, and low-voltage mercury lamps. Up to now, new types of lamps such as high-pressure sodium lamps and metal halide lamps have emerged on the market, greatly increasing the number of types, luminous efficiency, and service life of lighting lamps. At the same time, with the development of technology, the color rendering performance of lighting lamps has also been greatly improved. However, at the same time, the types of indoor circuit faults have also increased.
1. Related processes of indoor lighting circuits
The composition of lighting circuits includes power supply, wires, switches, and loads (lighting fixtures). The power supply also includes a low-voltage lighting distribution box, from which all the energy required for the lighting comes. The power supply also includes two different types of DC and AC power. AC power is generally supplied by Y/yn three-phase transformers, and the neutral wires in each phase box are single-phase power supplies. It is best to ensure the symmetry of the three-phase load during the load distribution process, and the power supply and lighting are connected by wires.
The processes that should be noted here include:
（1） Selection of wires. The allowable value of its current carrying capacity is very important, often referred to as the allowable current density; For exposed wiring, the selection values for wires of different materials are mostly as follows: aluminum wire is 4.5A/mm2, copper wire is 6A/mm2, and flexible wire is 5A/mm2
（2） Types and forms of switches. Switches have absolute control over current. Its load is the lighting lamp, which is the carrier that converts electricity into light. According to the different types of switches, the following three forms are generally used in line installation: A) A single switch controls one lamp: To ensure the safety of use and maintenance, the switch must be connected to the phase wire (i.e. live wire) during wiring processing, that is, after the switch is disconnected, the current of the lamp head will disappear accordingly. B) Set up two dual switches in different positions to control one lamp: It is commonly used in stairs or corridors, and this form has significantly expanded the control range of line connection or disconnection. This operation can be completed at both ends of the corridor, whether it is upstairs or downstairs. C) Two dual switches and one triple switch are set up in three locations to control one lamp: This form is also commonly seen in stairwells. For local lighting technology requirements below 36V, step-down transformers are often used for power supply. During the installation process, it is necessary to ensure that suitable fuses are connected in series to both the primary and secondary windings of the transformer. This can serve the needs of transformer faults and overload of the secondary winding, ensuring that the transformer is not damaged when the power supply is cut off in a timely manner. In addition to the above process requirements, the iron core and secondary winding of the transformer must also be foolproof during grounding or neutral installation.
2. Malfunctions and maintenance of indoor lighting circuits
(1) Short circuit fault and maintenance. A) Reasons for short circuit faults: The reason for short circuits in indoor circuits is often due to excessive current. Once the fuse cannot be blown in time, there is a possibility of burning out wires and other electrical equipment, and in severe cases, it may even cause fires. Short circuits can generally be divided into two different types: phase to phase short circuits and phase to ground short circuits. The latter also includes situations where there is a short circuit between the phase line and the neutral line, as well as a short circuit between the phase line and the ground. The main reasons for short circuits include: ① Wiring errors, caused by the contact between the phase wire and the neutral wire. ② Poor wiring or loose contact at the joint. ③ Not installing the plug according to the design requirements and inserting the wire head into the hole caused mixed wires The insulation layer or insulation resistance inside the electrical appliance is damaged, resulting in contact with the metal casing Water leakage in the house can cause excessive moisture or water ingress to the lamp head or switch The insulation of the wire is damaged due to external forces, and the damaged area is in contact with the power line or the ground. B) Maintenance of short circuit faults. When checking and eliminating short circuits, the electrical equipment in the fault area must be powered off first, and then the troubleshooting situation should be observed. If the fault cannot be eliminated, the switch and corresponding protective devices should be checked again. In addition, maintenance of wire insulation aging should be carried out. The reasons for insulation aging include: ① Pipeline lines and sheathed lines are prone to insulation aging due to factors such as leakage or overload on the line, which can cause the wire to be in an overloaded state for a long time. ② External mechanical damage causes damage to the insulation layer of the wire. To prevent the occurrence of faults caused by this problem, regular and irregular inspections should be carried out on the insulation resistance and structure of the insulation layer of the wire. Once the insulation resistance decreases or the insulation layer cracks, it must be replaced in a timely manner to ensure electrical safety Check the fuse of the fuse, remember that the fuse cannot be too thick, and copper wire, aluminum wire, or iron wire cannot be used instead, otherwise there is also a risk of short circuit.
(2) Circuit failure and maintenance: A) Reasons for circuit breaker faults: Breaking the circuit will also limit the normal operation of the line. The causes of open circuit faults include: ① Loose or detached connections at the wire ends. ② The mouse bit through the small section wire The wire may break under external force, which may be caused by mechanical pulling or other factors Small section wires are burned out under long-term overload or short circuit conditions Poor quality or damage during installation of single stranded small section wires can affect the normal functioning of the core wires within the insulation layer The connecting wires of the activity section were damaged due to overwork. B) Maintenance of circuit breaker faults: When carrying out circuit breaking fault maintenance on the line, the principle of section by section inspection should be followed to gradually narrow down the fault point and ensure the safety of inspection and handling. The general inspection steps are to ensure that the fuse inside the fuse is in a blown state. If it has already been blown, then check for short circuits or load conditions in the circuit; If the fuse is not blown and the power supply side phase line is not connected to the power supply, the previous level fuse should be checked immediately. If the fuse is also found not to be broken, the switch and circuit on the distribution panel (board) should be checked. By using the above elimination method, determine the cause of the fault and take corresponding measures to restore the smooth operation of the circuit.
(3) Leakage fault and maintenance: A) Reasons for leakage faults: Leakage is often caused by damage to the insulator. There are two types of leakage faults: phase to phase leakage and phase to ground leakage. The most obvious manifestation of leakage faults is an increase in electricity consumption, accompanied by overload or short circuit related phenomena such as melt burning, loose protective devices, and overheating of wires and equipment. The main causes of line leakage include: ① Insulation aging of lines and equipment. ② The installation of the line device was not completed according to the construction technical requirements The insulation performance of circuits and equipment decreases when they are exposed to moisture, heat, and chemical corrosion The repaired insulation layer does not meet the standard or the insulation tape is loose and affects its normal function. B) Maintenance of leakage faults : In troubleshooting leakage faults, the troubleshooting methods include: ① using a megohmmeter telemetry or other methods to determine if there is a leakage phenomenon. ② Determine the nature of electrical leakage. Method: When checking the connected ammeter, cut off the neutral wire and observe the change in current The leakage range can be determined by removing the shunt fuse or opening the shunt switch By sequentially disconnecting the lighting switches of the circuit and analyzing the indication of the ammeter, the specific leakage point can be identified. In short, corresponding solutions should be developed based on specific reasons, including replacing wires or equipment, ensuring that installation forms and technologies comply with relevant construction standards, and ensuring a suitable working environment for the line, such as no moisture or heat.
(4) Heating malfunction and maintenance: A) Reasons for heating faults: When there is heating of wires or heating of wire connection positions in indoor circuits, common fault factors include: ① The specifications of the wires used do not meet the technical requirements of the design. When the cross-section is small, it will cause the wires to overheat due to overload. ② When the capacity of electrical equipment increases beyond the load of the wires, and the area of the line wires does not increase accordingly, it can also lead to the occurrence of heating Lines, equipment, and various devices have leakage problems When a single current carrying wire passes through a replacement magnetic metal such as a steel pipe, it will generate heat The connection position of the wire increases the contact resistance due to looseness or looseness, causing heating. B) There are many problems with heating faults, but they are all easy to troubleshoot and discover. The factors that usually cause the faults are not complex, and as long as the heat source is found, it is easy to eliminate them.
3. Conclusion
In short, the installation of indoor lighting circuits is an important unit in the production internship teaching of maintenance electricians in technical schools, and the fault analysis and maintenance of indoor lighting circuits are the focus of this unit. Only by understanding the relevant installation processes, mastering the causes of indoor lighting circuit faults and corresponding maintenance methods, can students take corresponding measures to troubleshoot and provide guarantees for safe electricity use.
