Shanghai Times Light Lighting Appliance Testing Co., Ltd. Yu Licheng
Common explosion-proof luminaire main body structures usually have two types of explosion-proof: explosion-proof type "d" and increased safety type "e". The increased safety type luminaire has the same safety margin as the explosion-proof luminaire, and is more in line with the lighting fixture. Product features, higher cost performance. However, compared with the explosion-proof lamps, the types of light sources allowed by the increased safety lamps are relatively small, and the difficulty of product design is relatively high. It is necessary to comprehensively use the lighting electrical technology and the principle of explosion protection, which affects the development and application of the increased safety lamps. It also caused the current number of types of increased-energy lamps to be much smaller than those of explosion-proof lamps.
First, the definition
First, let us understand the increased safety lamps from the relevant terms and definitions. I have not found the definition of increased safety lamps, the related terms and definitions are as follows
Explosion-proof electrical equipment explosion-protected electrical apparatus
Electrical equipment that does not ignite in an explosive surrounding environment under specified conditions.
Increased safety type "e" increased safety "e"
An explosion-proof version of electrical equipment that does not generate arcing or sparking under normal operating conditions to increase its safety and prevent the possibility of dangerous temperatures, arcs and sparks in electrical equipment.
Luminaire
Any device that can distribute, reveal, or transform one or more light sources, and includes all components necessary to support, secure, and protect the light source (but not the light source itself), as well as the necessary circuit aids and A device that is connected to a power source.
Explosion-proof lighting explosion-protected luminaire
A luminaire that takes various specific measures to prevent ignition of the surrounding explosive mixture.
From the above terms and definitions, the key to the technology of the increased safety luminaire is to prevent the possibility of dangerous temperatures, arcs and sparks. So, what are the links in general lighting fixtures that can create dangerous temperatures, arcs and sparks? First, the source bulb is broken or leaking, which may cause the combustible gas mixture to enter the bulb and directly contact the hot electrode or the discharge tube, causing an explosion; the electrical connection of the lamp is loose, the contact is poor, and dangerous temperature may occur. Arc and spark; the insulation of the luminaire can not withstand excessive voltage, resulting in breakdown arc; the abnormal working state of the luminaire (such as rectification effect) that may occur at the end of the life of the light source may cause dangerous temperature of the luminaire control device; Dangerous temperatures, arcs, sparks, etc. can occur during a fault.
Explosion-proof luminaires adopting the increased safety type "e" explosion-proof type are to solve the above-mentioned various problems from the technology, in order to design an increased-energy type luminaire that meets the standard requirements.
From the above related terms and definitions to understand, I have defined the following as the summary of the increased safety lamps, which is for your reference only.
Increased safety lamp increased safety "e" luminaire
A main structure adopts an explosion-proof luminaire of an increased safety type "e" explosion-proof type. Further measures are taken to illuminate lamps that do not generate arcs or sparks under normal operating conditions, to increase their safety and to ensure that the luminaire does not generate dangerous temperatures throughout the working life (including when the light source ends and the lamp control device fails). Arc and sparks.
Second, the allowed light source and principle analysis
GB3836.3-2000 eqv IEC60079-7:1990 "Electrical equipment for explosive gas atmospheres Part 3: Increased safety type "e"" Standard 5.2.1 has clearly defined the light source allowed for increased safety lamps The IEC60079-7:2001 standard 5.3.1 further perfected the clause, and through learning, combined with the working principle of the electric light source to understand the clause.
The current light sources allowed for increased safety lamps are:
Fa6 single-pin fluorescent tube without starter;
G5 or G13 dual-pin fluorescent tubes without preheating the cathode starting and running circuits;
Ordinary incandescent lamp
Self-ballasted high pressure mercury lamp;
After the bulb is broken, the temperature of the light source part rapidly drops to other sources below the limit temperature.
Light source working principle analysis The working principle of the Fa6 single-pin non-starter fluorescent tube is that the conductive film is preheated through the conductive film on the wall of the lamp when the lamp is started to help the lamp start. Once the lamp is broken or leaking, the conductive film on the wall of the lamp will be broken or oxidized, causing the lamp to open and stop working.
The working principle of the G5 or G13 double-pin fluorescent tube without preheating the cathode starting and running circuit is to short the double pin of the lamp through the lamp holder connection, so that the filament of the cathode of the lamp does not pass current, and the lamp is activated when the lamp is started. The high frequency pulse voltage generated by the preheating start type electronic ballast breaks down the electric field in the lamp to start working. If the lamp is broken or leaking, the lamp stops working.
The working principle of an ordinary incandescent lamp is that the tungsten wire will emit light and heat through the current. Once the bulb is broken or leaked, the conductive tungsten wire will instantaneously oxidize and break.
The self-ballasted high-pressure mercury lamp is actually a tungsten filament inserted in a high-pressure mercury lamp. At the initial stage of the startup, the tungsten wire is energized and heated, and at the same time, the high-pressure mercury lamp acts as a preheating and ballast. Once the bulb breaks or leaks, the conductive tungsten wire will instantaneously oxidize and break, causing the lamp to open and stop working.
Other light sources that can be used for increased safety lamps are tungsten halogen lamps, a tungsten lamp filled with a halogen gas in the bulb, which works in the same way as an incandescent lamp.
The LED light-emitting diode works by applying an electric field to inject electrons and holes in the semiconductor material and to composite light. The semiconductor material is encapsulated in the light-emitting diode by plastic.
These light sources are analyzed according to their working principle. Even if the light source is broken or leaked, the combustible gas mixture may enter the bulb, and it is impossible to contact the hot tungsten wire, the electrode or the discharge tube to cause an explosion.
Among the above-mentioned light sources, ordinary incandescent lamps, self-ballasted high-pressure mercury lamps, and tungsten halogen lamps have low luminous efficiency, and the temperature of the surface of the light source usually exceeds 200 ° C. Therefore, when used as a light source for an increased safety lamp, the safety type is increased. The temperature group of the luminaire can only be set to T2 or T1, and the applicable explosive gas environment is less.
LED light-emitting diodes are still in the research and development stage, and the maximum power of LEDs that can be produced at present is 5W, and the economic cost is high. At present, most of the LEDs used in lamps are used for indication and decoration, not for illumination.
The most suitable light source for use as an add-on luminaire is the above two fluorescent lamps, the Fa6 single-pin, starter-free fluorescent tube and the G5 or G13 dual-pin fluorescent tube without preheated cathode starting and running circuits are designed for increased safety lamps. Developed by use, it has the characteristics of high luminous efficiency, low surface temperature of the light source and high safety. The temperature group of the increased safety lamps using the two fluorescent lamps can be at least T4 or T5, and the applicable explosive gas environment is very high. widely.
Third, the light source and principle analysis that is not allowed to use <br> At present, the light sources that are not allowed for the increased safety lamps are:
Ordinary fluorescent lamps (including double-ended and single-ended fluorescent lamps);
High-intensity gas discharge lamp (high-pressure sodium lamp, high-pressure mercury lamp, metal halide lamp);
Low pressure sodium lamp.
Analysis of the working principle of the light source The working principle of the ordinary fluorescent lamp is that after the lamp filament of the lamp is preheated, the high voltage is generated by the matched ballast, so that the cathode electron is excited to break down in the electric field of the lamp tube, so that the fluorescent lamp starts normal operation. After the filament is preheated, high voltage is generated by the ballast to excite the cathode electrons, which can slow down the cathode aging and prolong the life of the lamp. However, when used as a source of increased safety lamps, once the bulb of the lamp is broken or leaking, the combustible gas mixture may enter the bulb and directly contact the hot filament or electrode, causing an explosion.
After the high-intensity gas discharge lamp is completely broken, the discharge tube can still maintain electrical connection, and the hot discharge tube can ignite the combustible gas mixture once it is in direct contact with the combustible gas mixture, causing an explosion.
When any light source is broken or leaking, the internal light source cannot instantaneously disconnect the electrical connection, and the internal temperature of the light source is rapidly lowered. The flammable gas mixture may enter the blister and cause an explosion. Increased safety lamps cannot use light sources with similar dangers.
The low-pressure sodium lamp is different from the high-pressure sodium lamp. The high-pressure sodium lamp discharge tube mainly contains sodium molecules in the form of sodium mercury umbilical, which is relatively stable, while the discharge tube of the low-pressure sodium lamp contains more free sodium, and the free sodium chemical molecular form is unstable. Very active, once in contact with water or steam, free sodium and water molecules will undergo a violent chemical reaction, and at the same time will generate a lot of heat, which may ignite the flammable gas mixture in the environment, posing an explosion hazard. Therefore, the low-pressure sodium lamp can not be used not only in the increased safety lamps, but also all the explosion-proof lamps can not use the low-pressure sodium lamp. The low-pressure sodium lamp can not enter the place with explosive danger. Once someone brings the low-pressure sodium lamp into the place with explosive danger, it will fall accidentally. If the free sodium is in contact with the water molecules on the ground, a severe chemical reaction will occur, and there is a danger of explosion.
Fourth, electrical connection
The electrical connections of the luminaires are loose and poorly contacted, which can create dangerous temperatures, arcs and sparks. The electrical connection of the increased safety lamps should be firm and reliable, and will not loosen themselves. Additional measures should be taken for all electrical connection points of the lamps to improve their reliable connection.
There are many additional measures for electrical connection, such as the addition of a spring washer to the screw connection, the structure to prevent the conductor from slipping out, the mechanical connection and then welding. The specific requirements are clearly defined in GB3836.3-2000 eqv IEC60079-7:1990 Standards 4.1 and 4.2.
5. Lamp holder <br> Since the light source is a consumable part, the service life is much lower than that of the lamp. The light source needs to be replaced several times during the life cycle of the lamp. In order to facilitate the user to replace the light source, the lamp holder is specially designed as the light source. The installation provides convenient mechanical fixing and electrical connection. How to take additional measures for the lamp holder to ensure the electrical contact connection of the lamp holder is safe, reliable and convenient. GB3836.3-2000 eqv IEC60079-7:1990 Standard 6.3 .1 and Appendix A have related requirements for lamp holders.
1. The lamp holder shall take measures to prevent the lamp from loosening itself in the lamp holder.
2. The electrical contacts of the screw socket and the Fa6 single-pin fluorescent lamp holder shall be covered in the explosion-proof chamber, and the arc and spark caused by the loose electrical contact between the lamp cap and the lamp holder shall be controlled in the explosion-proof chamber. To prevent explosion hazard in the increased safety lamps.
3. IEC60079-7:2001 Clause 5.3.7 of the standard proposes the installation of a lamp holder for a G5 or G13 double-pin fluorescent lamp without a preheated cathode starting and running circuit. The lamp holder combines the two-pin circuit of the lamp tube and simultaneously Reliable spring clamping force is maintained for each pin, which reduces the probability of loose pin contact, which is in line with the additional measures of increased safety.
Sixth, insulation
If the insulation of the luminaire does not withstand excessive voltage, a breakdown arc will occur. Increased safety luminaires have taken additional measures to increase the clearance and creepage distance requirements for increased insulation performance, resulting in significantly improved insulation performance. GB3836.3-2000eqv IEC60079-7:1990 Standards 4.3 and 4.4 provide clear requirements for increasing clearance and creepage distance requirements.
7. The abnormal working state of the luminaire may occur when the light source is at the end of its life.
From the perspective of the light source allowed by the increased safety luminaire, only two types of fluorescent lamps may have an effect on the working state of the luminaire at the end of its life.
For an increased-energy luminaire using a Fa6 single-pin, starter-free fluorescent tube, the matching magnetic ballast may be affected by the rectification effect caused by the aging of the lamp. When the single-pin, non-starter fluorescent tube cathode aging is near the end of life, the cathode damage at both ends of the lamp is always in succession. When the cathode at one end of the lamp is damaged and the cathode at the other end is still normal, the alternating current through the electrical circuit of the lamp will generate one end. When the cathode is turned on and the cathode is disconnected at one end, the current flowing through the magnetic ballast changes from the original AC sine wave to the one-way half wave. At this time, the hysteresis of the magnetic ballast of the magnetic ballast will cause hysteresis. The one-way half-wave voltage gradually converges to DC, so that V0 in the silicon steel sheet deviates from the 0 position, causing magnetic flux saturation, causing the inductance to decrease, the impedance to decrease, and the current to increase greatly, which will further increase the hysteresis and eddy current. As a result, the temperature is greatly increased and a dangerous temperature is generated.
GB3836.3-2000 eqv IEC60079-7:1990 The standard 5.2.6 stipulates that the ballast of fluorescent lamps should be able to withstand the rectifying effect produced by the aging of the lamp, and its temperature must not exceed the limit temperature.
Another type of double-pin fluorescent tube used in the (instantaneous start) electronic ballast without preheating cathode starting and running circuit, because the tube cathode is not preheated and directly excited by high frequency pulse, will affect the use of the tube Lifetime, unless the lamp is specially designed for instant start-up of the lamp.
When the double-pin fluorescent tube ends its life, it will affect the working state of the lamp. The main performance is that the electronic ballast is damaged. If the electronic ballast has an abnormal protection function, the abnormal protection function will be activated to protect the electronic ballast. Avoid damage. The electronic ballast of the increased safety lamp shall be able to withstand the abnormal working state generated at the end of the life of the fluorescent lamp without damage.
Eight, light source control device failure
The control device (ballast) in the increased safety luminaire will have a fault condition at the end of its life. At this time, the temperature of the ballast will increase greatly until it burns out, which will generate dangerous temperature, arc and spark. Therefore, when designing the safety-enhanced luminaire, we must pay attention to the selection and design of the explosion-proof structure of the luminaire control device (ballast), and also consider whether the luminaire will generate dangerous temperature when considering the normal working state, the abnormal working state of the light source and the fault state of the control device. Arc and sparks.
First of all, from the perspective of electronic ballasts, at the end of their life, there is often a fault condition in which electronic components break down and burn out. Because of the complexity of their electronic circuits and the number of components, it is difficult to predict in advance what is the part. The components burn out, so it is difficult to estimate the exact temperature at which the fault occurred, and it can only be judged from the burn marks after the fault occurs. Since electronic ballasts always end up with faulty conditions in which components burn out, there are always dangerous temperatures, arcs and sparks inside. Therefore, the explosion-proof measures of electronic ballasts used in increased safety lamps should not be used. Increase the safety type "e", but use explosion-proof type "d" or potting type "m", sand-filling type "q" and other explosion-proof forms.
The theoretical life of an inductive ballast is ten years. During its entire working life, the lamp used is a consumable part, its service life is short, and it will definitely damage several parts. Therefore, the whole work of the ballast During the life span, it is inevitable that several abnormal work will occur. In some large-scale installations with poor maintenance, it can often be seen that the lamp ballast is in an abnormal working state for a long time due to the failure to replace the lamp in time. The abnormal operating temperature of the inductor ballast winding is much higher than the normal operating temperature. Take a tw130 common magnetic ballast as an example. The winding temperature is lower than 130 °C during normal operation, and the winding temperature will be close to 232 °C during abnormal operation.
When the life of the inductive ballast is about to end, a fault condition occurs, the insulating paint of the ballast coil begins to age, and the inter-turn insulation is gradually broken down. At the beginning of the inter-turn insulation breakdown, the internal resistance of the ballast is reduced and flows through. The current of the coil increases, the heating of the coil increases, and then the process of insulation breakdown and breakdown of the coil is further accelerated until the coil heating temperature reaches 350 ° C, the coil enameled wire is melted and blown, and the electrical circuit is broken, and this process is finally completed. If the explosion-proof measures of the inductive ballast are designed to increase the safety type "e", then the temperature group can only be set to T1, and the applicable range is too small and uneconomical. Inductive ballasts are usually designed as explosion-proof "d" or encapsulated "m", sand-filled "q" and other explosion-proof forms.
Even if the inductive ballast adopts the above-mentioned explosion-proof measures, it should strengthen the monitoring of the inductive ballast coil temperature and surface temperature, and calculate the coil temperature when the ballast is faulty by measuring the coil temperature and surface temperature. The highest surface temperature produced at 350 ° C is reached to determine the temperature group of the luminaire. If the ballast surface temperature is too high, thermal protectors can be used to limit, lower the maximum surface temperature and reduce the lamp temperature group.
IX. Integrity of safety requirements for explosion-proof lamps<br> The complete safety requirements for explosion-proof lamps shall include not only the explosion-proof safety requirements of the GB3836 eqv IEC60079 family standard, but also the general safety requirements of the GB7000/IEC60598 family of standards, between the two standard families. The corresponding relationship has been described in the scope of application of the IEC60079 and IEC60598 standards.
IEC60079-0:2000:
1 Scope
This standard does not specify requirements for safety, other than thosedirectly related to the explosion risk.
IEC60598-1:2003:
0.1 Scope and object
For explosion proof luminaries, as covered by IEC 60079, the requirements ofIEC60598(selecting the appropriate parts 2) are applied in addition to therequirements of IEC60079.In the event of any conflict between IEC60598 and IEC60079, the requirements of IEC60079 take priority.
IEC60079 only covers explosion-proof safety requirements and does not include other general safety requirements. The safety requirements for explosion-proof luminaires should include not only the explosion-proof safety requirements of IEC60079, but also the general safety requirements of IEC60598. When GB3836 eqv IEC60079 conflicts with the contents of GB7000/IEC60598, the requirements of GB3836 eqvIEC60079 should be preferred.
Since the IEC60079 family standard is for the explosion-proof safety requirements of various types of explosion-proof electrical appliances, it is impossible to explain the general safety requirements of each type of explosion-proof electrical appliances, and the general safety requirements of various types of explosion-proof electrical appliances should be consistent with their respective IEC General Safety Requirements Standard.
Explosion-proof luminaires are special luminaires whose safety performance must comply with the explosion-proof safety requirements of the GB3836 eqv IEC60079 family standard, and should also meet the general safety requirements of the GB7000/IEC60598 family of standards. If only evaluated according to GB3836 eqvIEC60079 standard, it can only prove its explosion-proof safety performance, but it can not explain whether its general safety performance is reliable. Once the general safety performance occurs, the electrical components are burnt out, the grounding is discontinuous, the outer casing protection and the insulation failure are seriously faulty. It may also cause an explosion. Such as temperature test (thermal test) and grounding:
Temperature test (thermal test)
GB3836 eqv IEC60079 standard only proposes the control requirements and basic test methods for surface temperature and cable inlet temperature for explosion-proof lamps, and GB7000/IEC60598 standard provides comprehensive assessment requirements for the thermal performance of explosion-proof lamps.
Grounding GB3836 eqv IEC60079 standard only requires the grounding connection and the minimum cross-sectional area of ​​the grounding wire for the explosion-proof luminaire, and the GB7000/IEC60598 standard provides a system for the grounding connection of the explosion-proof luminaire, grounding continuity, grounding resistance, grounding wire, etc. Requirements.
In summary, the explosion-proof luminaire safety certification test is not comprehensive enough to be tested according to the GB3836 standard, and the operability is not strong. We believe that the safety certification of explosion-proof lamps should be tested in accordance with the applicable provisions of GB3836 and GB7000 standards, to verify the explosion-proof safety performance of explosion-proof lamps, and to check the general safety performance of explosion-proof lamps. Completely evaluate the safety of explosion-proof luminaires.
Editor: China Lighting Network Leaves
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