Fluorescent lamps (LDS) are the first economical devices that appeared after traditional lamps with a filament. They relate to gas-discharge devices, where an element that limits the power in the electric circuit is required.
Throttle purpose
A choke for fluorescent lamps controls the voltage supplied to the electrodes of the lamp. In addition, he has the following purposes:
- surge protection;
- cathode heating;
- creating high voltage to start the lamp;
- limitation of electric current strength after start-up;
- stabilization of the lamp burning process.
To save throttle connected to two lamps.
The principle of operation of the electromagnetic ballast (EMPRA)
The first fluorescent lamp startup circuit, which has been created and is still in use, includes the following elements:
- throttle;
- starter;
- two capacitors.
The circuit of a fluorescent lamp with a choke is connected to a 220 V network. All parts connected together are called electromagnetic ballast.
When power is applied, the circuit of the tungsten spirals of the lamp closes, and the starter turns on in glow discharge mode. The current does not pass through the lamp yet. The threads gradually warm up. Starter contacts in the initial state are open. One of them is made bimetallic. It bends when heated by a glow discharge and closes the circuit. In this case, the current increases by a factor of 2–3 and the lamp cathodes are heated.
As soon as the starter contacts are closed, the discharge in it stops and the bimetallic plate begins to cool. As a result, the movable contact opens and self-induction of the inductor occurs in the form of a significant voltage pulse. It is enough for the electrons to break through the gas medium between the electrodes and the lamp to light up. A rated current begins to pass through it, which then decreases by 2 times due to a voltage drop across the inductor. The starter remains constantly off (contacts open) while the LDS is on.
Thus, the ballast starts the lamp and subsequently maintains it in an active state.
Advantages and disadvantages of EMPR
The electromagnetic choke for fluorescent lamps is characterized by low price, simplicity of design and high reliability.
In addition, there are disadvantages:
- pulsating light leading to eye fatigue;
- up to 15% of electricity is lost;
- noise at the time of launch and during operation;
- the lamp does not start well at low temperatures;
- large sizes and weight;
- long start of a lamp.
Typically, the humming and flickering of a lamp occurs when the power is unstable. Ballasts produce different levels of noise. To reduce it, you can choose the appropriate model.
Lamps and chokes are selected equal to each other in power, otherwise the lamp life will be significantly reduced. Usually they are supplied in the kit, and ballast replacement is done with a device with the same parameters.
Fluorescent lamps complete with EMPR are inexpensive and do not need to be set up for them.
For ballast, reactive energy consumption is characteristic. To reduce losses, a capacitor is connected in parallel with the power supply.
Electronic ballast
All the shortcomings of the electromagnetic inductor had to be eliminated, and as a result of research, an electronic inductor for fluorescent lamps (electronic ballasts) was created. The circuit is a single unit that starts and maintains the combustion process by forming a given sequence of voltage changes. You can connect it using the instructions supplied with the model.
The throttle for electronic type fluorescent lamps has the advantages:
- the ability to instantly launch or with any delay;
- lack of a starter;
- lack of blinking;
- increased light output;
- compactness and lightness of the device;
- optimal operating modes.
Electronic ballasts are more expensive than an electromagnetic device because of the complex electronic circuitry, which includes filters, power factor correction, inverter and ballast. In some models, protection against erroneous start of the lamp without lamps is installed.
The user reviews say about the ease of use of electronic ballasts in energy-saving LDS, which are built directly into the base for conventional standard cartridges.
How to start a fluorescent lamp using electronic ballasts?
When turned on from the electronic ballast, voltage is applied to the electrodes and they are heated. Then they receive a powerful impulse that lights the lamp. It is formed by creating an oscillatory circuit that enters into resonance before discharge. In this way, the cathodes are heated well, all the mercury in the bulb evaporates, so that the lamp starts up easily. After a discharge occurs, the resonance of the oscillatory circuit immediately ceases and the voltage decreases to the operating one.
The principle of operation of the electronic ballast is similar to the version with an electromagnetic inductor, since the lamp is triggered by a high voltage, which then decreases to a constant value and maintains a discharge in the lamp.
The current frequency reaches 20-60 kHz, due to which flicker is eliminated, and the efficiency becomes higher. In reviews, it is often proposed to replace electromagnetic chokes with electronic ones. It is important that they fit in power. The circuit can create an instant start or with a gradual increase in brightness. It is convenient to make a cold start, but at the same time, the lamp life becomes much less.
Fluorescent lamp without starter, throttle
LDS can be turned on without a bulky inductor, using a simple incandescent lamp with the same power instead. In this scheme, the starter is also not needed.
Connection is made through a rectifier, in which the voltage is doubled with the help of capacitors and ignites the lamp without heating the cathodes. In series with the LDS, an incandescent lamp that limits the current is switched on through a phase wire. Capacitors and rectifier bridge diodes should be selected with a margin of acceptable voltage. When supplying the LDS through the rectifier, the bulb on one side will soon begin to darken. In this case, you need to change the polarity of the power.
Connecting a fluorescent lamp without a choke, where an active load is used instead, gives a weak brightness.
If you install a choke instead of an incandescent lamp, the lamp will glow much stronger.
Throttle Health Check
When the LDS is not lit, the reason lies in the malfunction of the wiring, the lamp itself, the starter or throttle. Simple causes are identified by the tester. Before checking the throttle of the fluorescent lamp with a multimeter, disconnect the voltage and discharge the capacitors. Then the switch of the device is set to dialing mode or to the minimum limit of resistance measurement and are determined:
- coil winding integrity;
- winding electrical resistance;
- interturn circuit;
- open circuit in coil winding.
The reviews suggest checking the throttle by connecting it to the network through an incandescent lamp. With an interturn circuit, it burns brightly, and a working one - it fills up.
If a malfunction is detected, the throttle is easier to replace, since repairs can be more expensive.
Most often, the starter in the circuit breaks down. To check its performance, a known-good one is connected instead. If the lamp still does not light up, then the reason is different.
The throttle is also checked using a working lamp by connecting two wires from it to its base. If the lamp lights up brightly, then the throttle is operational.
Conclusion
The choke for fluorescent lamps is being improved in the direction of improving technical characteristics. Electronic devices begin to displace electromagnetic ones. At the same time, old versions of models continue to be used due to their simplicity and low price. It is necessary to understand the whole variety of types, to properly operate and connect them.