Home  Ballasts

Jan 21 2020

The Working Principle, Main Performance and Common Terms of Ballast

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Ⅰ Introduction of Related Nouns

1.1 Explanation of Some Related Nouns

1.2 The Main Performance and Parameters of Discharge Lamp

Ⅱ Ballasts

2.1 The Working Principle of the Ballast

2.1.1 Inductance Ballast

2.1.2 Electronic Ballast

2.2 Functions of the Ballast

2.2.1 Limit the Starting Current of the Lamp to A Suitable Range

2.2.2 The Open Circuit Voltage Provided Is Sufficient for the Lamp to Start Smoothly

2.2.3 Prevent the Lamp Power from Changing Greatly

2.2.4 Working Current of Automatic Control Lamp

2.3 The Main Performance Indicators of the Ballast

2.3.1 Supply Voltage and Frequency

2.3.2 Allowable Tolerance of Power Supply Voltage

2.3.3 Power Factor

2.3.4 Starting Current

2.3.5 Working Current

2.3.6 Short-circuit Current

2.3.7 Current Form Factor

2.3.8 Power Consumption of Ballast

2.3.9 Interturn Insulation of Ballast

2.3.10 Dielectric Strength and Insulation Resistance of Ballast

2.3.11 Temperature Rise of Ballast

2.4 Classification of Ballast

2.4.1 Two Types of Ballast: Electronic Ballast and Inductance Ballast

2.4.2 Classification of Inductance Ballast: Impedance Ballast, Magnetic Leakage Ballast

Ⅲ Characteristics of Impedance and Magnetic Leakage Ballasts

3.1 Impedance Ballast

3.2 Magnetic Leakage Ballast

Ⅳ Common Terms for Ballast / Electronic Ballast

4.1 Ballast Loss

4.2 Ballast Factor

4.3 Ballast Efficacy Factor

4.4 Crest Factor

4.5 Power Factor

4.6 Total Harmonic Distortion

4.7 Parallel vs Series Circuit

4.8 Audible Noise

4.9 Active/Passive Power

4.10 High Output

4.11 EMI/EMC/EMS

4.12 AC/DC Exchangeable

4.13 Flicker

4.14 Protection Circuit

4.15 Dimmable Electronic Ballast

4.16 Applicable Range of Temperature

4.17 Lamp Life

4.18 Glue

 

1.1 Explanation of Some Related Nouns

 Electric light source: A device that converts electrical energy into optical radiation energy (sometimes also used in some types of luminaires).

— Discharge lamp: A lamp that emits light by the discharge of gas, metal vapor, or a mixture of several gases and metal vapor.

 Figure 1. Discharge Lamp

Figure 1. Discharge Lamp

— Metal vapor (discharge) lamps: Lamps that emit light by metal vapor discharge, such as mercury (vapor) lamps, sodium (vapor) lamps, etc.

— Mercury (vapor) lamp: A lamp that emits light due to the discharge of mercury vapor.

 Figure 2. Mercury (Vapor) Lamp

Figure 2. Mercury (Vapor) Lamp

— High-pressure mercury (vapor) lamp: When the discharge is stable, the mercury vapor partial pressure reaches or exceeds 10,000 Pa.

 Figure 3. High-pressure Mercury (Vapor) Lamp

Figure 3. High-pressure Mercury (Vapor) Lamp

— Sodium (vapor) lamp: A lamp that emits light mainly by the discharge of sodium vapor.

Figure 4. Sodium (Vapor) Lamp 

Figure 4. Sodium (Vapor) Lamp

— High-pressure sodium (vapor) lamp: When the discharge is stable, the partial pressure of sodium vapor in the lamp reaches or exceeds 10,000 Pa.

 Figure 5. High-pressure Sodium (Vapor) Lamp

Figure 5. High-pressure Sodium (Vapor) Lamp

— Metal halide lamp: A discharge lamp that emits light by the discharge of a mixture of metal vapor and a metal halide decomposition product.

Figure 6. Metal Halide Lamp 

Figure 6. Metal Halide Lamp

— Ballast: A device that stabilizes the discharge of a discharge lamp.

Figure 7. Ballast 

Figure 7. Ballast

1.2 The Main Performance and Parameters of Discharge Lamp

— Starting time: the time required to turn on the power switch of the discharge lamp until the lamp can work.

— Restarting time: Discharge power after the discharge lamp has stably worked, and the time required from the time the power is turned on again to the lamp is restarted.

— Starting voltage: The minimum voltage required between the electrodes when the discharge lamp begins to discharge continuously.

— Lamp current: The current passing through the light source's lamp contact when the light source is operating steadily.

— Rated voltage: The designed operating voltage of the lamp (DC or AC rms).

— Rated current: The designed current of the lamp at the rated voltage.

— Rated power: The designed power of the lamp.

 

Ⅱ Ballast

2.1 The Working Principle of the Ballast

2.1.1 Inductance Ballast

When an AC power supply of 220V 50HZ is applied in the switch closed circuit, the current flows through the ballast, and the lamp filament starter heats the filament (the starter is disconnected at the beginning, because an AC voltage greater than 190V is applied, the arc discharge of the gas in the jumper in the starter causes the bimetal to heat and deform, and the two electrodes are close together to form a path to heat the filament). When the two electrodes of the starter are close together, there is no arc discharge, the bimetal is cooled, and the two poles are separated. Because the inductance ballast is inductive, when the circuit is suddenly disconnected, a pulse voltage of 600V-1500V will be generated at the two ends of the lamp for about 1ms. The exact voltage value depends on the type of the lamp. In the case of discharge, the voltage across the lamp immediately drops. At this time, the ballast restricts the lamp current on the one hand, and makes a phase difference of 55 to 65 between the power supply voltage and the operating current of the lamp on the other hand, so as to maintain the secondary starting voltage of the lamp and make the lamp works more stably.

Due to its simple structure, the inductance ballast is the first ballast to work with fluorescent lamps, and its market share is relatively large. Due to its low power factor, poor low-voltage start-up performance, bulky energy consumption, and flicker, etc., it is slowly being replaced by electronic ballast.

Energy loss of inductance ballasts: 40W (lamp power) + 10W (self-heating loss of the inductance ballast) = 50W, that is, the total power consumption of the entire lamp.

Figure 8. Inductance Ballast 

Figure 8. Inductance Ballast

2.1.2 Electronic Ballast

An electronic ballast is a converter that converts power-frequency AC power to high-frequency AC power. Its basic working principle is:

The working frequency power supply becomes a DC power supply after passing through a radio frequency interference (RFI) filter, full wave rectification and a passive (or active) power factor corrector (PPFC or APFC). Through DC / AC converter, high-frequency AC power of 20K-100KHZ is output, which is added to the LC series resonance circuit connected to the lamp to heat the filament, so that the lamp tube is changed from discharging to being on state, and then emitting light. At this time, the high-frequency inductor plays a role in limiting the increase of current to ensure that the lamp can obtain the lamp voltage and lamp current required for normal operation. In order to improve reliability, various protection circuits are often added, such as abnormal protection, surge voltage and current protection., temperature protection and so on.

Figure 9. Electronic Ballast 

Figure 9. Electronic Ballast

2.2 Functions of the Ballast

2.2.1 Limit the Starting Current of the Lamp to A Suitable Range

Starting current refers to the current through the lamp within 30 seconds after the lamp is powered on or during lamp preheating process. In general (especially in the state of lowest temperature), the starting current is much larger than the operating current of the lamp, so each lamp has a maximum starting current. If the starting current is too large, the service life of the lamp will be shortened; if the current is too small, the lamp cannot be preheated to the normal starting state or the process from glow discharge to arc discharge cannot be completed. The starting current provided by the ballast should not only start the lamp in a short time, but also not affect the normal service life of the lamp.

2.2.2 The Open Circuit Voltage Provided Is Sufficient for the Lamp to Start Smoothly

When the open-circuit peak voltage of the ballast is used as the starting voltage of the lamp, it must be sufficient to ionize the gas in the gas discharge lamp, that is, to generate a peak current that causes a glow-to-arc transition discharge between the electrodes, so that the lamp can start to work. High-pressure mercury lamps and metal halide lamps are more difficult to start at low temperatures, and the open-circuit peak voltage provided by the ballast must be sufficiently high.

2.2.3 Prevent the Lamp Power from Changing Greatly

Although the lamp has a certain range of voltage values during the design and delivery of the lamp, the voltage value of the lamp changes during actual use and throughout its life. This requires the matching ballast to adjust it within a certain range, so that the lamp power does not change significantly. The ideal ballast should be such that the lamp power of the newly used lamp and the lamp near the end of its life are not too different.

2.2.4 Working Current of Automatic Control Lamp

Stable impedance within a certain voltage range is the basic condition that the impedance ballast can control the working current of the lamp. The ballast uses the time change rate of the voltage proportional to the current to adjust the working current of the lamp. When the open circuit voltage in a certain period causes the lamp operating current to increase, the inductive effect of the ballast will limit the rate of current increase; when the current starts to decrease, the inductive effect will prevent the rate of current decrease.

2.3 The Main Performance Indicators of the Ballast

2.3.1 Supply Voltage and Frequency

Each ballast is marked with the power supply voltage and frequency used, and should be installed and used in strict accordance with regulations. Otherwise, the lamp cannot be operated at the design point, and in serious cases, the ballast and the lamp will be directly damaged.

2.3.2 Allowable Tolerance of Power Supply Voltage

The voltage value of the power grid changes with the peak and trough of the electricity consumption. Under normal circumstances, the ballast can start the lamp within the range of ± 8% of the rated power supply voltage deviation. However, the specific location of the user is different, and the output voltage of its power distribution system varies greatly. For example, if the range of the power supply voltage is greater than the allowable range of the ballast, the lamp will fail to start, will be unstable after starting, and will not reach the predetermined luminous flux. And the voltage will be too high to damage the ballast and lamp.

2.3.3 Power Factor

Ballasts with higher line power factors can reduce the costs of the configuration and operating of power distribution systems. Ballasts with a power factor of ≥ 0.85 are called high power factor ballasts, and general ballasts (such as impedance ballasts) can only reach about 0.5. Compensation capacitors should be connected when installing and using ballasts.

2.3.4 Starting Current

The process of the gas discharge lamp from glow discharge to arc discharge at start-up has a relatively large current at the beginning. It should be strictly controlled according to technical indicators during design, manufacture and inspection.

2.3.5 Working Current

The working current of the ballast is designed based on the working current of the lamp. Considering the discreteness of the performance of the iron chip and the ability of process control in the production process, the allowable deviation is given in the product standard to meet the need to stabilize the working current of the lamp. (Generally it is ± 5% of standard current).

2.3.6 Short-circuit Current

The ballast works with the lamp. When the lamp head is short-circuited, the grid voltage will be all added to the ballast. Therefore, the short-circuit current of the ballast at the rated supply voltage of 106% should be limited. Full consideration should be given in the design, otherwise serious consequences will occur such as burning the ballast.

2.3.7 Current Form Factor

When the ballast works with the lamp, the current waveform factor will cause the lamp electrode to emit material to evaporate too quickly, the stability of the luminous flux output to deteriorate, and the anode life to be shortened accordingly if it is too large. The limit value of the form factor is specified in the ballast standard: the form factor of the mercury lamp ballast is not greater than 2, that of the sodium lamp ballast is not greater than 1.8, and that of the metal halide lamp ballast is not greater than 2.2.

2.3.8 Power Consumption of Ballast

The main materials that make up the ballast are iron chips and enameled wires. The former shows iron loss and the latter shows copper loss. When the material is selected improperly during design or excessively engraved, the loss will be excessive. If the volume of the ballast is determined, the excessive loss will also cause the temperature rise to be too high and affect the service life of the ballast.

2.3.9 Interturn Insulation of Ballast

The layer-turn insulation of the ballast coil is ensured by the insulation performance of the film of the enameled wire. When the film of the enameled wire is uneven, falls off or is abraded during the winding process, short circuit will occur until it burns out when it is powered on or after a period of operation. Therefore, detection during production is an effective control method.

2.3.10 Dielectric Strength and Insulation Resistance of Ballast

When the ballast is energized, it will generate transient overshoot voltages of several times or dozens of times the supply voltage in the windings. At the same time, the high and low temperature shocks that the ballast undergoes during the transition between working and standby states will cause the insulation material between the coil winding and the iron core to deteriorate, leading to the deterioration of the insulation performance. Because the winding of the ballast is connected to the power grid, it is necessary to test the electrical strength and insulation resistance between the winding and the core.

2.3.11 Temperature Rise of Ballast

After the ballast is energized, it will generate a certain loss (collectively referred to as power consumption) when it is no-load or working with the lamp. Its loss is composed of copper loss and iron loss. The former is generated by the wire material that composes the winding, and the latter is generated by the silicon lamination of the core material. When the ballast works with the lamp, the working current flows through the winding, and the product of the copper group of the square winding of the current is the copper loss power (referred to as copper loss); at the same time, the core is affected by the induced electromotive force of the winding to generate a higher magnetic flux density, and eddy current loss and hysteresis loss (referred to as iron loss) are generated in the core. The heat generated by these two losses causes the ballast to heat up and the temperature to rise, which is called temperature rise. The operating life of the ballast depends on the life of the insulating material. The operating life of the ballast is inversely proportional to the operating temperature of the ballast. The operating temperature of the ballast is equal to the sum of the ambient temperature and the temperature rise of the ballast. When the insulation material of the ballast is determined, the lower temperature rise can make the ballast work at a higher ambient temperature. Therefore, it is beneficial to reduce the temperature rise of the ballast as much as possible to the applicability and service life of the ballast.

2.4 Classification of Ballast

2.4.1 Two Types of Ballast: Electronic Ballast and Inductance Ballast

Electronic ballast: The electrical energy of the grid is converted by electronic components, and the requirements of voltage and current needed by the supplementary lamp are met by AC or DC power.

Inductance ballast: The electrical energy of the grid is converted by iron chips and coils, and the AC power is used to meet the requirements of the needed voltage and current.

2.4.2 Classification of Inductance Ballast: Impedance Ballast, Magnetic Leakage Ballast

Impedance ballast: The main magnetic circuit has a full air gap iron chip and a single winding coil. Based on the principle of linear induction impedance, the starting current and working current of the supplementary lamp are limited to a stable working range.

 Figure 10. Electrical Schematic of Impedance Ballast

Figure 10. Electrical Schematic of Impedance Ballast

Magnetic leakage ballast: It is mainly composed of an iron chip with an air gap in the main magnetic circuit part and two winding coils plus a separate magnetic circuit sheet. The primary winding receives power from the power grid, and the tap of the primary winding is connected to the secondary winding. According to the principle of electromagnetic induction, electric energy is induced at the secondary winding and the starting capacitor end to meet the required starting voltage and stable working current of the supplementary lamp. Boost and magnetic leakage, the two characteristics of the ballast have formed many characteristics different from impedance ballasts.

Figure 11. Electrical Schematic of Magnetic Leakage Flux Ballast 

Figure 11. Electrical Schematic of Magnetic Leakage Flux Ballast

 

Ⅲ Characteristics of Impedance and Magnetic Leakage Ballasts

3.1 Impedance Ballast

The impedance type inductance ballast is an impedance choke coil, which is used in series with the HID light source. Its role is to limit the current to a certain range under a certain voltage, to ensure that the light source is within a safe range of starting current when the light source starts, and to maintain a certain working current after the light source normally emits light. It is a constant current component.

Its advantages:

1. The circuit is simple and easy to maintain. It consists of a compensation capacitor, an electronic trigger and an impedance ballast. The circuit has a power factor which is ≥ 0.85.

2. Reliable and stable performance. In a series circuit, the impedance ballast plays the role of a heart. The remaining compensation capacitors and electronic triggers are auxiliary components. Because the ballast can be used at a coil temperature of 130°C, working continuously for ten years (through TUV experimental certification in Germany), then the ballast will not be damaged if the light source is not damaged.

3. It has a wide range of applications and can be used in high temperature environments without being affected by the failure of the compensation capacitor. Its reliability is especially prominent among the integrated lamps.

4. When the line is working, the power consumption of the ballast itself is small, and it is also an energy-saving product.

Its weaknesses:

1. The starting current is large. The starting current is about 1.5 times the working current. Because of the large starting current, the line capacity must be increased by 1.5 times during the design of the line, which is also a large cost.

2. When the light source is working, the lamp power is greatly affected by the increase of the power supply voltage. Basically, when the power supply voltage changes by 10%, the lamp power changes by more than ± 30%, which will affect the life of the light source.

3. In the light source with high tube pressure, the maximum service life of the light source is not fully met, because the tube voltage will self-extinguish when the line voltage exceeds 154V in the line voltage of 220V, and the tube pressure will increase with the years of use of the lamp tube. Of course, there are many factors that affect the life of the light source, including the quality of the lamp itself; the design parameters of the ballast and the adaptability of the light source. In short, the use of impedance is also a weak point in ensuring the maximum life of the light source.

4. Under abnormal conditions, after the two wires of the lamp head are short-circuited, the current of the ballast is very large, and the heat is also very large, which will cause the circuit to be damaged for a long time.

 Figure 12. Impedance Ballast

Figure 12. Impedance Ballast

3.2 Magnetic Leakage Ballast

The magnetic leakage ballast is a type of LC leading peak type circuit. The fundamental wave is mutated by auto-coupling boost and local magnetic saturation, and then it resonates with the working capacitor to obtain a higher open-circuit voltage and longer-lasting lamp operating current. It is a kind of high power factor lighting circuit, the line power factor reaches 0.90 ~ 0.97, which has its unique advantages for point HID light sources.

Its advantages:

1. The starting current is small, and the starting current is less than the working current. In the design of the line, it is not necessary to consider increasing the line capacity and this can reduce a large investment.

2. The voltage fluctuates but the lamp power is constant. When the voltage fluctuates by ±10%, the lamp power change can be within 10%, so that the life of the light source is extended.

3. The higher open circuit voltage can extend the life of the light source. The general open circuit voltage of the magnetic leakage ballast is above 300V (especially metal halide lamps), which can provide a higher open circuit voltage than the impedance type, which greatly meets the requirements of open-circuit voltage × 70% ≥ tube voltage.

4. The line power factor is relatively high, generally can be designed between 0.9 ~ 0.97, is a high power factor green lighting products.

5. Under the abnormal condition that the two wires of the lamp head are short-circuited, the incoming line current is less, which will not affect the entire system.

Its weaknesses:

1. The volume is larger than the impedance type, and the cost is higher than the impedance type.

2. Its output relies on a series start capacitor to start lighting. The capacitor plays a very important role. If the capacity of the capacitor changes greatly, it will directly affect the lumen output of the bulb, but because the capacitance is affected by the temperature, there is a large limitation, the requirements of performance and temperature resistance of the capacitor are very high.

3. Because the temperature of the capacitor is limited, the environment used is worse than that of the impedance ballast.

Figure 13. Magnetic Leakage Ballast 

Figure 13. Magnetic Leakage Ballast

 

Ⅳ Common Terms for Ballast / Electronic Ballast

4.1 Ballast Loss

This value represents that the energy consumed by the electronic ballast itself is converted into heat energy instead of light energy. This value can be calculated by subtracting the power consumed by all lamp tubes from the total output power. Generally speaking, the traditional 40W dual-lamp ballast consumes about 22W, while the electronic ballast consumes about 7W.

4.2 Ballast Factor

This value can show the relative effect of the light output of the electronic ballast. The value is the percentage obtained by dividing the measured light output of the electronic ballast by the light output of the standard ballast light. Generally speaking, the higher the value, the better the light output effect. For electronic ballasts, it must not be less than 0.9, but there are also electronic ballasts designed to emphasize high output values and its light output ratio can be up to 1.18 to 1.28.

4.3 Ballast Efficacy Factor

This value can be obtained by dividing the light output ratio (Ballast Factor) by the ballast input power value (Input Power). In the US market, sellers usually use this value to measure and compare the pros and cons of the efficiency of various electronic ballasts. The higher the value, the better the efficiency of the electronic ballast.

4.4 Crest Factor

It is also called wave height rate. This value has a direct and critical impact on the life of the lamp tube. Most lamp tube manufacturers recommend that this value is preferably less than 1.7. Excessively high values can easily cause blackening of the lamp tube and shorten the service life of the lamp tube. The definition of the crest factor refers to the peak current divided by the average current when an electronic ballast is used to light a fluorescent tube.

4.5 Power Factor

This value can represent the efficiency value of the electronic ballast to convert the external input voltage and current into available power. The higher the power factor value, the better the company that supplies the power system (referred to as the power company). In order to encourage consumers to use electronic ballasts with high power factors, foreign power companies have adopted a subsidy policy, but consumers generally think that the higher the PF value, the more power they save. This is a wrong concept because the amount of power saved is not related to the PF value.

4.6 Total Harmonic Distortion

Generally, when the frequency cycle(50 / 60HZ) of a three-phase power supply system is a multiple of three(3, 6, 9, 12), it is easy to cause distortion of the sine wave of the alternating current, resulting in improper high current and causing damage to electrical equipment. For electronic ballasts, the safety regulations of all countries clearly stipulate that the total harmonic (Total Harmonic Distortion, THD) value must be less than a specific value. The European IEC, American ANSI, Taiwan CNS, and Japanese JIS require that the THD value must be less than 33%. However, in the US market, electronic ballasts are divided into two levels. One is the level of THD which is more than 20%, another is the level of THD that is less than 20%. In general, in places where computer acoustics are used extensively or precision electronic instruments or equipment are used, a more rigorous or lower THD value should be used.

4.7 Parallel vs Series Circuit

When an electronic ballast can light up two lamp tubes at the same time, a parallel or series circuit will be involved. If one of the lamp tube fails, the other lamp will immediately goes out, and its design is in series. If the other lamp tube is still on, its design is a parallel design. Generally speaking, the parallel type requires two sets of separate circuits, which is more expensive than the series one set of circuits. However, designing a parallel type circuit is not simple. The main reason is that when one of the lamp tube fails, it must be properly handled to avoid power or frequency transfer to the other lamp tube. If the circuit is not properly handled, it will cause the other lamp tube to increase its load and accelerate its failure.

4.8 Audible Noise

In all countries, electrical ballast safety regulations stipulate noise standards for electronic ballasts. Generally speaking, the noise produced by electronic ballasts is 75% lower than that of traditional ballasts. CNS stipulates that the noise of electronic ballast must be less than 33db.

4.9 Active/Passive Power

Electronic ballast is designed to improve the power factor. Active power factor (active correction) or passive power factor (passive correction) circuits can adopt it. The difference between the two is whether the power will be affected by the change when the voltage changes, which will cause the light output to change and cause flicker. If the passive power factor circuit is used, the power factor cannot be increased to above 0.99. At the same time, the voltage will change, and the power will change with it. Sometimes the lamp tube will even flicker. If an active power factor circuit is used in the design, the above problems can be avoided. In other words, active power factor models should be used in areas with unstable voltages.

4.10 High Output

The design of electronic ballasts can be carried out in two directions, one is to save energy, and the other is to increase light output. If electronic ballasts are designed in the direction of high output, special attention must be paid to the matching lamp tubes. You must choose a lamp tube specially developed for the use of electronic ballasts instead of the traditional lamp tubes in order to design high-output electronic ballasts. Its characteristics are particularly high tube pressure, and the use of thicker filament. For example, the HF high-frequency lamp tube in the Japanese market and the T832W high-frequency lamp tube in Europe and the United States belong to this type of lamp tube. After opening the filament structure, you can find that the high-frequency lamp tube has a thicker wire diameter. (Stick Coil), which can withstand higher currents.

4.11 EMI/EMC/EMS

Any high-frequency electronic products will generate noise. Electronic noise interference can be divided into two aspects: conducted interference and radiated interference. Generally speaking, conducted interference will affect the normal operation of the other electronic products, and radiation interference affects other equipment through space. For the use of electrical supplies, the electrical safety regulations of most countries have regulations for preventing electromagnetic interference, such as European IEC (EN55015), the United States FCC PART 18, Japan's JIS, etc. All of them have standards for preventing electromagnetic interference for commercial use and households. Among them, European regulations in this regard are the most severe. Generally speaking, the company's computer processing center, places using precision electronic instruments or testing equipment, hospitals, broadcast rooms, etc., places that are extremely afraid of electromagnetic interference, should use electronic ballasts that meet EMI / EMC regulations.

4.12 AC/DC Exchangeable

The electronic ballast is very suitable for emergency lighting because it saves power. If an electronic ballast with AC and DC design is used, the time of emergency lighting and light output can be extended, the quality of public safety can be improved, and the chance of personal injury and death can be reduced.

4.13 Flicker

Generally, the lighting frequency of the traditional ballast is the same as the frequency of the power supply system, and the frequency is 50 or 60 cycles per second (50 / 60Hz). In this case, the flashing degree of the lighting is about 33%. The electronic ballast, due to high-frequency lighting, has a frequency of 20K to 50K, and its flicker degree is less than 5%. If active power factor is used, its flicker degree may be less than 2%. The higher this value is, the more comfortable it is for the eyes, and the less fatigue there is.

4.14 Protection Circuit

Basically, the structure of electronic ballasts is quite precise. There are hundreds of or at least 60 electronic parts in an electronic ballast. In addition to providing the current for the stable operation of the lamp tube, various sudden phenomena that will damage the electronic ballast must be prevented. In order to provide long-term guaranteed quality, the protection circuit design of a well-designed electronic ballast must be quite thoughtful, which should include the following special conditions.

 Open/Short Circuit Protection

 Inrush Current Protection

 Over High Voltage Protection

 Over Low Voltage Protection

 End of Lamp Life Protection

 Lamp Leakage Protection

 Static Prevernion

 Auto Reset

4.15 Dimmable Electronic Ballast

If the electronic ballast has a dimmable function, it is called a dimming electronic ballast. The technology of the dimming electronic ballast lies in the dimming amplitude, such as 50%, 20%, 10%, or even 1%. The degree of dimming. Generally, the dimming electronic ballast must combine the following functions, which can save energy up to 80%;

 Daylight Detection Dimming Function

 Time Switch Function

 Remote Switch Function

 Object Detection Switch Function

4.16 Applicable Range of Temperature

Generally, the temperature change has a considerable impact on the function or life of electronic parts. Therefore, electronic ballast must be used within their specified temperature range. Due to the considerable difference in temperature between regions, for example, countries in the cold and tropical regions have different requirements for the applicable temperature range. For Taiwan, it is necessary to consider the applicable temperature as high as 60 ℃.

4.17 Lamp Tube Life

The life of the lamp tube has a considerable correlation with the starting method of the electronic ballast. Please refer to the starting method and the wave height ratio of the electronic ballast. If you choose a high-quality electronic ballast, you can not only save electricity, but also extend the lamp tube life by more than 50%. However, if you choose a high output electronic ballast, you can only maintain the original life of the lamp tube.

4.18 Glue-filling

Many electronic ballasts on the market use glue-filling to enhance the heat dissipation effect to reduce the impact of temperature on electronic parts, but they are heavy and large, which are not convenient for the use of ultra-thin lamps. At present, the US market that uses glue-filling type has also gradually moved to European-style electronic ballasts that are lightweight and do not require glue-filling.

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