A ballast resistor is a device that acts as a current limiting device on a fluorescent lamp and generates an instantaneous high voltage. It is made by wrapping an enameled wire on a core made of silicon steel. Such a coil with an iron core is turned on/off instantaneously. At this time, a high voltage is generated by self-induction, and it is applied to the electrodes (filaments) at both ends of the fluorescent tube. This action is alternated. When the starter (bubble) is closed, the filament of the lamp is regulated by the ballast to conduct heat;
When the starter is open, the ballast will generate high voltage and add it to the filaments at both ends of the tube. The filament emits electrons to bombard the fluorescent powder on the tube wall. The starter repeats several times and it will repeat. Several such actions are performed to open the lamp. When the lamp is normally illuminated, the internal resistance becomes small, and the starter is always kept open, so that the current is stably operated through the lamp tube and the ballast, so that the lamp normally emits light. Since the ballast always has electric current when it is working in the fluorescent lamp, it is easy to generate vibration and it will generate heat. Therefore, the fluorescent lamp with the ballast, especially when the ballast is of poor quality, will produce a large sound. It takes a long time and it is easy to burn. Ballast sub-electronic ballasts and magnetic ballasts.
Electric device
When a 220V 50HZ AC power source is applied in the switch-closed circuit, current flows through the ballast, and the lamp filament starter heats the filament (the starter is turned off at the beginning, due to the application of an AC voltage greater than 190V) The arc of the gas in the bubble in the starter is discharged, so that the bimetal is heated and deformed, and the two electrodes are brought together to form a passage for heating the filament), when the two electrodes of the starter are close together, because there is no arc Discharge, bimetal cooling, two poles separated, because the magnetic ballast is inductive, when the circuit is suddenly interrupted, a pulse voltage of 600V-1500V will be generated at both ends of the lamp for about 1ms, the exact voltage value depends on the lamp The type, in the case of discharge, the voltage across the lamp immediately drops, at which point the ballast limits the lamp current on the one hand and 55 between the supply voltage and the operating current of the lamp on the other hand. To 65. The phase difference is such that the secondary starting voltage of the lamp is maintained, so that the lamp can work more stably.
Due to its simple structure, the inductor ballast is a ballast that works as the first type of fluorescent lamp. Its market share is still relatively large due to its low power factor, poor low-voltage startup performance, cumbersome energy consumption, stroboscopic and other shortcomings. Its market is slowly replaced by electronic ballasts. Inductive ballast energy loss: 40W (lamp power) + 10W (inductive ballast self-heating loss) is equal to the total power consumption of the entire set of lamps is 50W.
Electronic ballast
The electronic ballast is a converter that converts power frequency AC power into high frequency AC power. The basic working principle is:
The power frequency power supply becomes a DC power supply after a radio frequency interference (RFI) filter, full-wave rectification, and passive (or active) power factor corrector (PPFC or APFC). Through the DC/AC converter, the high-frequency AC power supply of 20K-100KHZ is output, and is applied to the LC series resonant circuit connected to the lamp to heat the filament, but the lamp is "discharged" to become "on" state, and then enters the illuminating state. At this time, the high-frequency inductor acts to limit the current increase, ensuring that the lamp tube obtains the lamp voltage and lamp current required for normal operation, and in order to improve the reliability, various protection circuits such as abnormal protection, surge voltage and current protection are often added. , temperature protection and more.
multimeterMultimeters, also known as multiplex tables, multimeters, tri-meters, and multi-use meters, are indispensable measuring instruments for power electronics and other departments. Generally, voltage, current and resistance are the main purposes. The multimeter is divided into a pointer multimeter and a digital multimeter according to the display mode. It is a multi-functional, multi-range measuring instrument. The general multimeter can measure DC current, DC voltage, AC current, AC voltage, resistance and audio level, etc. Some can also measure AC current, capacitance, inductance and semiconductor. Some parameters (such as β) and so on.
The multimeter can be used not only to measure the resistance of the object being measured, but also to measure the DC voltage. Even some multimeters can measure the main parameters of the transistor and the capacitance of the capacitor. Fully mastering the use of the multimeter is one of the most basic skills of electronic technology. Common multimeters have pointer multimeters and digital multimeters. The pointer multimeter is a multi-function measuring instrument with a head as the core component, and the measured value is read by the head pointer. The measured value of the digital multimeter is displayed directly by the liquid crystal display in digital form, which is convenient to read, and some also have a voice prompt function. The multimeter is a meter that shares a meter head, a voltmeter, an ammeter, and an ohmmeter.
The DC current file of the multimeter is a multi-range DC voltmeter. The parallel closed-circuit divider resistor of the meter head can expand its voltage range. The DC voltage range of the multimeter is a multi-range DC voltmeter. The meter series resistor divider can expand its voltage range. The voltage divider resistors are different and the corresponding ranges are different. The head of the multimeter is a magnetoelectric measuring mechanism. It can only convert the alternating current into direct current through a direct current, and realize the measurement of the alternating current.
Multimeter measuring ballast is good or badFrom the figure, we can draw conclusions: exchange-communication: no positive or negative. Positive electrode - negative electrode: the negative electrode to the positive electrode, the positive electrode to the negative electrode. Communication - positive and negative: communication to positive communication, negative to communication. Other conduction is bad.
There are two ways to test the quality of the ballast:
1, power-on test; 2 million meter electrical blocking static test.
First: First, you prepare a 220V40W light bulb, connect it to the ballast and connect it to the power supply. Listen carefully to the sound of the ballast and observe the brightness of the bulb. If the bulb is not lit or the bulb filament is dark red, the bulb brightness Constant (refers to the brightness of the bulb connected to the power supply in parallel under normal conditions) indicates that the ballast is faulty.
Fault resolution:
1. The bulb does not light: there is an open circuit (open circuit) fault inside the ballast;
2 The filament is dark red: there is a virtual connection inside (poor contact) 3 The brightness of the bulb is constant: there is a short circuit inside.
The second type: static test, adjust the multimeter to the electric blocking R*1000 file, connect the test pen to the ballast if the reading is 0, the internal short circuit, the reading is infinity, the internal open circuit, there is a reading but it is not normal.
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