Difference between inductance ballast and electronic ballast

I. Inductance ballast

Inductance ballast is an electronic device that uses traditional steel sheet coils to drive electric light sources to produce the required lighting.

1. Working principle

(1) Inductive device:

An inductor is an element that stores energy and consists of a coil or solenoid. When the current through an inductor changes, it creates a self-induced emf that tries to stop the drastic change in current. This means that the inductive device resists rapid changes in current, stabilizing the current flow in the circuit.

(2) Initial stage:

When the light is first lit, the resistance is small and the current will increase rapidly. With the help of the magnetic ballast, the inductive device will prevent the sharp rise of the current, so that the current increases relatively slowly.

(3) Stable stage: 

Once the current reaches a stable value, the inductance device still plays the role of stabilizing the current. When the current changes (such as voltage fluctuations), the inductance device will generate a self-induced electromotive force, thereby adjusting the rate of change of the current to keep it relatively stable.

(4) Delayed lighting: 

Magnetic ballasts can also provide a delayed lighting effect. After the light is turned on, due to the blocking effect of the inductance, the gradual increase of the current causes the brightness of the bulb to gradually increase instead of reaching the maximum brightness immediately.

2. Advantages and disadvantages

(1) Advantages:

① Almost no longevity issues.

② Composed of traditional steel sheet coils, it is not easily damaged.

(2) Disadvantages:

① The power factor is low.

② Light output cannot be adjusted.

③ Changing work hours is long, and safety is low.

④ There may be slight noise during use.

⑤ It is necessary to add a starter (its price is low), and it will start to flash.

⑥ With low working frequency, people with sensitive eyesight will feel the lights flicker severely.

3. Types

(1) Flux leakage ballast

It is mainly composed of an iron sheet with an air gap in the shape of the main magnetic circuit, a coil with two windings and a magnetic circuit sheet. The primary winding draws power from the grid, and the taps of the primary winding are connected to the secondary winding. Using the principle of electromagnetic induction, electric energy is induced at the secondary winding and starting capacitor end to meet the requirements of matching lamp starting voltage and stable working current. The boost and flux leakage characteristics of the ballast create many characteristics different from impedance ballasts. 

① Features:

A. Due to the limited temperature of the capacitor, the environment is harsher than that of the impedance ballast.

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

C. The output is connected in series with a capacitor to activate the lighting. Capacitors play a very important role. If the capacitance of the capacitor changes greatly, it will directly affect the lumen output of the bulb, but the capacitance is greatly limited by temperature. Therefore, the performance and temperature resistance requirements of the capacitor are very high.

② Advantages:

A. The voltage fluctuates but the lamp power is constant. When the voltage fluctuates by ±10%, the lamp power can be changed within 10%, prolonging the life of the light source.

B. The line power factor is relatively high, generally it can be designed between 0.9 and 0.97. It is a high power factor green lighting product.

C. In the abnormal situation that the two wires of the lamp are short-circuited, the input current is small and will not affect the entire system.

D. The starting current is small, less than the working current. We don't need to consider increasing the line capacity when designing the circuit, which can reduce the large investment.

E. Higher open circuit voltage can prolong the life of the light source. Flux leakage ballasts generally have an open circuit voltage above 300V (especially metal halide lamps), which can provide a higher open circuit voltage than impedance type. Greatly meet the requirements of open circuit voltage × 70% ≥ tube pressure.

(2) Impedance ballast

It is composed of full air gap iron sheet of main magnetic circuit and single winding coil. The principle of linear inductive impedance limits the starting current and operating current of the matched lamp within a stable working range.

① Features:

Impedance inductor ballasts are impedance choke coils used in series with HID light sources. Its function is to limit it to a certain current under a certain voltage, so that the starting current when the light source is started is within a safe range. It is a constant current element when the light source is normally on and kept at a certain operating current.

② Advantages:

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

B. It has a wide range of applications, can be used in high temperature environments, and will not be affected by the failure of compensation capacitors. Its reliability is particularly prominent in integrated luminaires.

C. Reliable and stable performance. In a series circuit, the impedance ballast acts as the heart. The remaining compensation capacitors and electronic triggers are auxiliary working components. Since the ballast can work continuously for ten years at a coil temperature of 130°C (tested by German TUV), the ballast will not be damaged and the light source will not be damaged.

D. Simple circuit, easy maintenance. It consists of compensation capacitors, electronic triggers and impedance ballasts. Circuit power factor ≥ 0.85.

③ Disadvantages:

A. Under abnormal circumstances, after the two wires of the lamp are short-circuited, the current of the ballast is very large, and the heat is also large, which may cause damage to the circuit after a long time.

B. The starting current is large, and the starting current is about 1.5 times of the working current. Due to the large starting current, the line capacity should be increased by 1.5 times during line design, which is also a relatively large cost.

C. In light sources with high lamp voltage, the maximum service life of the light source cannot be fully satisfied. Because the lamp voltage will self-extinguish when the line voltage of 220V exceeds 154V, and the lamp voltage will increase with the increase of the service life of the lamp. Of course, there are many factors that affect the life of the light source, such as the quality of the lamp itself; the design parameters of the ballast and the compatibility of the light source. In conclusion, the use of impedance is also a weak point to guarantee the maximum lifetime of the light source.

D. When the light source is working, the power of the lamp is greatly affected by the rise of the power supply voltage. 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) According to the installation form

① Integral ballast:

Ballasts that form an irreplaceable part of the luminaire and cannot be tested separately from the luminaire.

② Built-in ballast:

Specially designed ballasts that can be installed in luminaires, boxes or boxes. The control room at the base of the lamp post is thought to be a case.

③ Independent ballast:

A ballast that can be installed separately from the luminaire without the need for an additional housing. It could be a built-in ballast with a suitable housing that provides the required protection as marked on the logo.

II. Electronic ballast

Electronic ballast is an electronic device that use electronics to drive an electric light source to produce the required illumination. Modern fluorescent lamps are increasingly using electronic ballasts, lightweight and compact, and even electronic ballasts can be integrated with lamps, etc. At the same time, electronic ballasts can usually be combined with the function of a starter, so that a separate starter can be dispensed with.

Electronic ballasts can also have more functions, such as improving or eliminating the flickering phenomenon of fluorescent lamps by increasing the current frequency or current waveform (such as becoming a square wave); it is also possible to use DC power for fluorescent lamps through the power inversion process.

1. Working principle

Electronic ballasts are converters that convert industrial frequency AC power into high frequency AC power.

First, the commercial frequency power is transformed into a DC power source through an RFI filter, a full-wave rectifier, a passive power corrector, or an active power factor corrector. Secondly, it is transformed into high-frequency AC power through a DC/AC converter. Then it adds the converted high-frequency AC power to the LC series resonant circuit to heat the filament, and at the same time generates a resonant high voltage on the capacitor to make the lamp tube change from the conduction state to the luminous state. At this time, the high-frequency inductance plays a role in limiting the increase of current, ensuring that the lamp tube obtains the voltage and current required for normal operation. It is also possible to add protection circuits such as abnormal protection, current protection, and temperature protection to complete various required functions. 

2. Advantages

① Low noise. The noise of high-quality electronic ballasts can reach below 35db, and people can't feel the noise.

② The starting point is more reliable. After preheating the lamp, the starting point was successful once, avoiding multiple starting points.

③ Prolong the lamp life. Factors such as constant wattage and reduced lamp current for high-quality products, as well as reliable starting points, result in longer lamp life.

④ Eliminate strobe and make the light more stable. It is beneficial to improve visual resolution and improve efficacy; it can reduce visual fatigue of continuous operation and help protect eyesight.

⑤ Stable input power and output luminous flux: high-quality products have good voltage stabilization performance. When the power supply and voltage deviation are large, they can still maintain a constant power of the light source and stabilize the illuminance, which is conducive to energy saving.

⑥ High power factor. Fluorescent lamps above 25W that meet national standards have a power factor higher than 0.95. However, it should be noted that the national standard stipulates a high harmonic limit for lamps below 25W, so that the power factor drops to 0.7-0.8.

⑦ It can be dimmed. For places that require dimming, such as places where incandescent lamps or tungsten-halogen lamps were used for dimming, replace them with high-efficiency fluorescent lamps and dimmable electronic ballasts, which can achieve a wide range of dimming from 2% to 100%.

⑧ Energy saving. Electronic ballasts for fluorescent lamps, more than 20-60khz frequency supply lamps, so that the luminous efficiency of the lamps than the industrial frequency increased by about 10% (according to the length of 4 feet of lamps), and their own power consumption is low, so that the lamps of the total power input decreased by about 20 percent, with better energy-saving effect. ballasts lights

3. Types

Generally, there are many kinds of electronic ballasts in the market:

① High efficiency electronic ballast:

Generally, the electronic types are collectively referred to as high efficiency, because the electronic type is high frequency, and the power factor is better than the traditional type.

② Instant start electronic ballast without preheating:

Instant start non-preheating type electronic ballast, the lamp tube starts instantly when the light is turned on, but because the filament at the end of the lamp tube is subjected to a sudden high starting voltage, the lamp filament is easily broken after a short period of time, and the life of the lamp tube is short. According to the test, if it is turned off for 25 seconds and turned on for 35 seconds, the number of times it is turned off is only about 2000 to 3000 times.

③ Preheating type starting electronic ballast:

Preheating type starting electronic ballast, the circuit is designed to start slowly, and the lamp will not light up until about 1-2 seconds when the light is turned on. The filament at the end of the lamp only bears the starting voltage that is slowly boosted, and the filament of the lamp is not easy to break, The lamp is more durable. According to the test, if it is turned off for 25 seconds and turned on for 35 seconds, the number of times it can be turned off can be as high as 15,000 times. 

4. Suggestions on the selection of electronic ballasts

Electronic ballasts have obvious advantages in improving the energy efficiency and quality of lighting systems. They are products recommended by New International and will also be the trend of future development.

Selection suggestions:

(1) High-quality, low-harmonic products should be selected. Instead of simply pursuing low price, they should meet the technical requirements of use, consider the effect of operation and maintenance, and make a comprehensive comparison.

(2) In places where dimming is required, tricolor fluorescent lamps can be equipped with dimmable digital ballasts to replace incandescent lamps or halogen lamps, which can greatly improve energy efficiency.

(3) The selected product should not only examine its total input power, but also its output luminous flux. According to regulations, the ballast coefficient (μ) should not be lower than 0.95. The European Union stipulates the energy efficiency level of the ballast, and also stipulates that the ballast coefficient μ≥0.96. ballasts pcb

(4) When choosing a fluorescent lamp less than 25W, as mentioned above, the harmonic limit specified in the GB17625.1-2003 standard is very wide. If it is used in a large number of buildings, it will lead to various adverse consequences. Effective measures should be taken to limit the design.

(5) In continuous tense visual work places and places with high visual requirements (such as design, drawing, typing, etc.), in places that require special quietness (wards, consulting rooms, etc.) and places where young people watch (classrooms, reading rooms, etc.) should be preferred.

III. Differences between inductance ballast and electronic ballast

Here are some differences between inductance ballast and electronic ballast.

1. From the point of view of nature

(1) Inductive ballast:

When the current in the coil changes, it will cause a change in the magnetic flux in the coil, thereby generating an induced electromotive force in the opposite direction to the current direction, thereby hindering the change in current.

(2) Electronic ballast:

It refers to the electronic equipment that uses electronic technology to drive the electric light source to produce the required lighting.

2. From the effect point of view:

(1) Electronic ballasts are easy to start and adapt to a wide range of voltages. However, inductance ballasts are difficult to start under low voltage conditions.

(2) The frequency of the electronic ballasts is high, and the light flickering cannot be felt. The inductance ballast is a power frequency, and you can feel the flicker.

(3) There will be a sound when the silicon steel sheet in the inductance ballast is loose, but this problem does not exist in the timing of the electronic ballast.

(4) Inductance ballasts are more durable and not easy to break. And some electronic products, especially low-quality electronic products without warranty, are prone to failure. ballast headlights

3. From the point of view of the start-up conditions:

(1) Temperature: The excitation energy of the inductance ballast is low when it starts, so it needs to start normally at 10°C. The electronic ballast can even be started at -25°C.

(2) Voltage inductor ballast cannot start when the power supply voltage is lower than 180V, and electronic ballast can start normally when the grid voltage is 100V.