Wiring diagram for fluorescent lamps: with choke, starter, without them

With the increase in electricity prices, we have to think about more economical lamps. Some of these use daylight lighting. The wiring diagram for fluorescent lamps is not too complicated, so even without special knowledge of electrical engineering you can figure it out. 

The principle of operation of a fluorescent lamp

Daylight fixtures use the ability of mercury vapor to emit ultraviolet waves when exposed to electricity. In the range visible to our eyes, this radiation is transferred by substances – phosphors.

Therefore, a conventional fluorescent lamp is a glass bulb, the walls of which are coated with a phosphor. There is also some mercury inside. There are two tungsten electrodes that provide electron emission and heating (evaporation) of mercury. The flask is filled with an inert gas, most often argon. The glow begins in the presence of mercury vapor heated to a certain temperature.

But normal mains voltage is not enough to evaporate mercury. To start work, in parallel with the electrodes, ballasts (abbreviated PRA) are turned on. Their task is to create a short-term voltage jump necessary to start the glow, and then limit the operating current, preventing its uncontrolled increase. These devices – PRA – are of two types – electromagnetic and electronic. Accordingly, the schemes are different.

Schemes with a starter

The very first circuits with starters and chokes appeared. These were (in some versions, there are) two separate devices, each of which had its own socket. There are also two capacitors in the circuit: one is connected in parallel to stabilize the voltage, the second is located in the starter housing, it increases the duration of the starting pulse. All this “economy” is called – electromagnetic ballast. Diagram of a fluorescent lamp with a starter and a choke in the photo below.

This is how it works:

• When the power is turned on, the current flows through the inductor, enters the first tungsten filament. Further, through the starter it enters the second spiral and leaves through the neutral conductor. At the same time, the tungsten filaments gradually heat up, as do the starter contacts.
• The starter has two contacts. One fixed, the second movable bimetallic. In the normal state, they are open. When current is passed, the bimetallic contact heats up, which causes it to bend. Bending, it connects to a fixed contact.
• As soon as the contacts are connected, the current in the circuit instantly increases by 2-3 times. It is limited only by the throttle.
• Due to the sharp jump, the electrodes heat up very quickly.
• The bimetallic starter plate cools down and breaks contact.
• At the moment of breaking the contact, a sharp voltage jump occurs on the inductor (self-induction). This voltage is sufficient for the electrons to break through the argon medium. Ignition occurs and gradually the lamp enters the operating mode. It comes after all the mercury has evaporated.

The operating voltage in the lamp is lower than the mains voltage for which the starter is designed. Therefore, after ignition, it does not work. In a working lamp, its contacts are open and it does not participate in its work in any way.

This scheme is also called electromagnetic ballast (EMB), and the operation scheme of an electromagnetic ballast is EMPRA. This device is often referred to simply as a choke.

The disadvantages of this fluorescent lamp connection scheme are enough:

• pulsating light, which negatively affects the eyes and they quickly get tired;
• noise during start-up and operation;
• inability to start at low temperatures;
• long start – about 1-3 seconds pass from the moment of switching on.

Two tubes and two starters

In luminaires for two fluorescent lamps, two sets are connected in series:

• the phase wire is fed to the inductor input;
• from the throttle output it goes to one contact of the lamp 1, from the second contact it goes to the starter 1;
• from starter 1 goes to the second pair of contacts of the same lamp 1, and the free contact is connected to the neutral power wire (N);

The second tube is also connected: first the throttle, from it – to one contact of the lamp 2, the second contact of the same group goes to the second starter, the starter output is connected to the second pair of contacts of the lighting fixture 2 and the free contact is connected to the input neutral wire.

The same connection diagram for a two-lamp fluorescent lamp is shown in the video. It might be easier to deal with the wires this way.

Wiring diagram for two lamps from one throttle (with two starters)

Almost the most expensive in this scheme are chokes. You can save money and make a two-lamp lamp with one throttle. How – see the video.

Electronic ballast

All the shortcomings of the scheme described above stimulated research. As a result, an electronic ballast circuit was developed. It does not supply a mains frequency of 50 Hz, but high-frequency oscillations (20-60 kHz), thereby removing the blinking of light, which is very unpleasant for the eyes.

The electronic ballast looks like a small block with output terminals. Inside there is one printed circuit board on which the entire circuit is assembled. The block has small dimensions and is mounted in the body of even the smallest lamp. The parameters are selected so that the start-up occurs quickly, silently. You don’t need any other devices to work. This is the so-called non-starter switching circuit.

Each device has a diagram on the reverse side. From it it is immediately clear how many lamps are connected to it. Information is duplicated in the inscriptions. The power of the lamps and their number, as well as the technical characteristics of the device, are indicated. For example, the block in the photo above can serve only one lamp. The wiring diagram is on the right. As you can see, there is nothing complicated. Take the wires, connect the conductors to the indicated contacts:

• connect the first and second output contacts of the block to one pair of lamp contacts:
• the third and fourth are served to another pair;
• supply power to the input.

All. The lamp is working. The circuit for switching on two fluorescent lamps to electronic ballasts is not much more complicated (see the diagram in the photo below).

The advantages of electronic ballasts are described in the video.

The same device is mounted in the base of fluorescent lamps with standard cartridges, which are also called “economy lamps”. This is a similar lighting device, only heavily modified.