LED lamp power connection design choice

1, the lamp power connection method

Common lighting and power connections are:

1 terminal block, the power cord is connected to the inside of the lamp;

2Connect the lead wires, connect the Power Cable to the lamp connection leads, and put them into the lamp housing or the junction box specified in the manual to protect the internal wires and terminals;

3 Non-removable flexible cable or cord, the electrical connection system of the luminaire is led out of the luminaire casing, connected to the power source by a non-removable flexible cable or cord connection plug or into the junction box;

4 Non-removable flexible cable or cord + with plug or appliance socket, suitable for portable lamps. When used normally, the lamp can be easily moved from one place to another after being connected to the power supply;

5 plug with socket, suitable for socket-mounted luminaires;

6 Adapters connected to the power rail for rail mounted luminaires;

7 appliance socket, use the power connector to insert the appliance socket installed on the lamp housing to complete the power connection of the lamp, such as the fluorescent lamp strip with loop connection;

8 screw or bayonet cap for semi-luminaires.

Among the above-mentioned lamp power connection modes, the most common lamp power connection modes are the first three, which can be applied to various lamps and have versatility, and most of the lamps can be selected by any of the above-mentioned power connection methods 1 to 3. The last five power connection methods are suitable for the special structure and use of the luminaire, with speciality and specificity, and no comparability.

2. Comparison of common lamp power connection methods

2.1 Differences in common lamp power connection methods

Since the above three power connection modes are applicable to various lamps, most of the lamps can be selected in any of the three power connection modes, which are comparable and related. We can use FIG. 1 to briefly explain The difference between the three power connections.

figure 1

figure 1

The buried luminaire shown in Figure 1 adopts a power connection method of "non-removable flexible cable or cord". The electrical connection system of the luminaire is led out of the luminaire casing by a non-removable flexible cable, and is connected to the power source. If the non-removable cable is removed, the lamp can only be connected to the terminal block by introducing the power cable into the lamp cavity. This type of power connection is called a “terminal”. If the terminal block is removed together, the lamp can only be connected into the lamp cavity and then connected to the terminal block to connect the power cable to the internal connection of the lamp. This type of power connection is called "connection lead". ".

The structure configuration of the three power connection methods is shown in Table 1. Usually, the power connection accessories are provided by the customer.

Table 1 Configuration of common lamp power supply connection

2.2 Characteristics of three types of lamp power connection

The three lamp power supply connections have their own characteristics, which can be applied to the power connection of most lamps. All kinds of lamps can choose the appropriate power connection according to the characteristics of each power connection.

1 Terminal: Connect the power cable into the lamp and connect it in the terminal block to ensure sufficient insulation protection. Advantages: convenient power connection and reliable wiring. Disadvantages: Need to reserve wiring space in the lamp cavity, and install the power connection part (including some internal wiring + terminal block + part of the power line).

2 Connecting the lead wire: Connect the inner wire of the lamp to the power cable by using the terminal block. Then, put the power connection part into the lamp housing or according to the terminal box specified in the manual, so that the power connection part is fully insulated. If the lamp has a wiring space, it is similar to the first type of power supply connection described above. Advantages: Reduce the cost of the terminal block. Disadvantages: Requires the customer to configure the terminal block, also need to reserve wiring space in the lamp cavity, and install the power connection part.

If there is no wiring space in the luminaire, the luminaire manufacturer needs to specify in the manual that after the internal conductor of the luminaire is connected with the power cord, the connection part should be placed in the junction box that meets the requirements of the specification, so that all the internal wiring outside the luminaire and The terminal block is fully insulated and the junction box provides wiring for the luminaire. Advantages: The luminaires reduce wiring space and reduce the cost of the terminal block. Disadvantages: Customers need to customize the junction box and terminal block that meet the specified requirements.

3 Non-removable flexible cable or cord: The electrical system of the luminaire is led out of the luminaire casing by a non-removable flexible cable or cord. The connecting plug or the junction box is connected to the power supply. The non-removable flexible cable or cord must meet the requirements. External wiring requirements. Advantages: The luminaire can reduce the wiring space, and it is not necessary to open the luminaire casing during installation to facilitate the sealing of the luminaire. Disadvantages: Customers need to have a power connection plug or power connection junction box with the protection level of the enclosure and the fixture, adding non-removable flexible cable or cord, which increases the installation cost.

2.3 Comparison of three types of lamp power connection

From the comparison of the above three power connection methods, the lamp with the connection lead power connection method has the lowest manufacturing cost, but it is a trouble to complete the lamp power connection by the standard method. Such power connection luminaires are very common in the United States and Japan because the building codes in these two countries are very perfect, and there are detailed standardization requirements for the electrical installation parts in the building, usually the wall position of each fixed installation luminaire. The standard electrical junction box for connecting the power supply to the lamp is pre-embedded. Therefore, the lamp with the connecting lead can be directly mounted on the outer surface of the junction box, and the connection lead is directly introduced into the junction box to complete the connection with the power source. Since there is no such standard in China's housing construction, the installation position of the lamps often does not have a pre-installed standardized electrical junction box. Therefore, the lamps connecting the leads are often unable to implement the standard installation, resulting in an unregulated power connection.

The IEC standard esteems the power connection method of the terminal block. It is suitable for the safe use habits of most countries in the world. It only needs to introduce the power cord into the lamp and connect it in the terminal block to ensure the terminal block is fully insulated. The power connection is convenient and the wiring is reliable. The structure of the luminaire with terminal connection power connection is relatively complete, and the customer can conveniently and reliably use without adding additional accessories.

The most important advantage of a luminaire with a non-removable flexible cable or cord is that the luminaire's electrical system is led out of the luminaire housing with a non-removable flexible cable or cord. It is not necessary to open the luminaire housing for easy sealing of the luminaire. Because the manufacturer is worried that the power cord will be connected into the luminaire for connection, it is necessary to open the luminaire at the installation site, and then install the luminaire after the power cord is connected. It is easy to cause the seal of the outdoor luminaire cable inlet to be damaged, and the luminaire casing protection is invalid. Therefore, it is preferred to increase the cost. Many luminaires with waterproof and dustproof enclosures use a non-removable cable or cord connection. In fact, this kind of worry is unnecessary. It is not difficult to manufacture a cable-inducing device with good sealing performance by the current manufacturing technology. A variety of cable-inducing device structures with good sealing performance are available, and the lamp standard has also been The assessment requirements for the cable entry device are specified.

3. Relevant standard requirements

In GB7000.1/IEC60598-1 "Lamps - Part 1: General Requirements and Tests" standards, the requirements related to the above three common power connection methods are as follows:

3.1 Terminal block

For related standard requirements, see Article 4.7 of GB7000.1/IEC60598-1. If the power cord may be stressed during use of the luminaire, appropriate precautions should be taken to prevent the cord from coming off and to charge the metal parts. There are many ways to preventive measures. For example, install a wire holder on the connecting wire near the terminal to prevent the stress on the power line from being transmitted to the terminal. It is also possible to add insulation to the wiring space to prevent the wire from falling off. Contact metal parts and so on.

The wiring of the power terminal is often connected by the customer. Because the customer's operation is not very professional, the installation environment (such as light and space) is poor, and there is also a lack of inspection after installation. The strand conductors are not inserted into the terminals, the free conductors may come into contact with accessible metal parts, and the free conductors of the ground lines may hit live parts, resulting in unsafe lighting. Therefore, the power supply terminal must be increased in safety protection to prevent the contact of free conductors. See Figure 2.

The standard requirements for terminal components are given in Chapters 14 and 15 of GB7000.1/IEC60598-1. Terminal block components are required for all three power connections.

Figure 2 Multi-strand wire is not fully inserted into the terminal block

3.2 connection leads

For related standard requirements, see Article 4.6 of GB7000.1/IEC60598-1. The connecting leads of the luminaire and the power cord need to be connected by a separate terminal block. The terminal block and internal wiring need to be protected. Wiring space should be provided for this terminal in the luminaire, or provided with the luminaire or manufacturer. The wiring space provided in the specified junction box accommodates the terminal block. If the manufacturer does not provide the terminal block or does not specify the size of the terminal block, the wiring space should at least accommodate the terminal block and connection as shown in Figure 3. Wire.

Figure 3 Installation layout of the luminaire with connecting leads using the terminal block

After the wiring space is installed in the terminal block and the wires, ensure that the creepage distance and clearance are in accordance with the standard. The connected wires must not be excessively sharp. After the terminals are connected, one of the conductors may be free and should not be touched. To any accessible metal part. If the terminal block does not have a fixed position, the wiring space should ensure that the unfixed terminal block can meet the same requirements as described above at any position.

After the terminal block is connected to the conductor, it shall be placed in the luminaire or in the junction box provided with the luminaire or specified by the manufacturer. If the terminal block cannot be placed in the luminaire, and the junction box is not provided with the luminaire, the manufacturer shall The form, size and power connection requirements of the junction box and terminal block are clearly and clearly communicated in the manual.

3.3 Non-removable flexible cable or cord

For related standard requirements, see Article 5.2 of GB7000.1/IEC60598-1. Non-removable flexible cables or cords shall comply with the requirements for external wiring of the luminaire. The mechanical and electrical properties shall comply at least with the requirements of the relevant insulated cable standards. The standard shall also refer to the conductor cross-sectional area of ​​the flexible cable and the thickness of the insulating layer, and the cable-inducing population. Protective measures, wire holders, etc. have raised relevant requirements.

The non-removable flexible cable or cord will eventually be connected to the power supply by the customer or connected to the junction box. The wiring space in the plug and junction box also needs to meet the standard requirements.

4, the common three power connection methods

The standard wire connection method recommended by the standard is to be done using terminal blocks to ensure the reliability of the wire connection. The terminal block and wires of the power connection of the luminaire need to be protected, and a wiring space is required. If there is no wiring space in the luminaire, a junction box is required to provide wiring space. The standard wiring method is shown in Table 1.

From the configuration and standard requirements of the above three power connection methods, there is an inclusive relationship with each other. The connection between the lamp connection lead and the power supply needs to be completed by using the terminal block. Therefore, the lamp with the connecting lead wire needs to be equipped with the terminal block and the wiring space when it is connected to the power supply according to the standard requirements, and should be related to the "connection lead + terminal block". The standard requirements. The terminal block and wiring space can be supplied by the manufacturer or by the customer. Usually the power connection accessories listed in Table 1 are provided by the customer.

After the power connection is completed by the luminaire with connecting leads, if the connecting leads cannot be installed in the luminaire housing or the junction box, and there is no effective insulation protection, the connecting leads need to meet the requirements of the external wiring of the luminaire, that is, non-removable soft. For cable or cord related standards, the exposed connecting leads are non-removable flexible cables or cords. Therefore, non-removable flexible cables or cords should be connected in a way that is compatible with "connecting leads + terminals + non-removable soft". Cable or cord" related standard requirements.