High-pressure mercury arc lamps are a type of electric lamp. These devices are widely used in lighting large objects and streets. Such light sources have high light output, a wide range of power, but rather low color rendering, which limits their use in relatively small rooms.
In the article we consider the characteristics of the "DRL 250" lamps, the light flux that they emit and the principles of their operation.
Lamp device
The abbreviation "DRL" means "arc mercury lamp", which is due to the principle of operation of the device. Lamps of this type can be connected in two versions - with and without a choke. In the second case, you need to use a special scheme.
Arc mercury lamps consist of three functional parts: a socle, a quartz torch and a glass bulb:
- The purpose of the cap is the reception of mains electricity through the connection of a threaded and point contact of the lamp with the contacts of the cartridge. After that, alternating electricity is transferred to the electrodes of the burner.
- A quartz burner is a quartz bulb with electrodes located on its sides. The internal volume of the burner is filled with argon - an inert gas and droplets of mercury.
- The outer shell of the lamp is a bulb made of heat-resistant glass containing nitrogen inside, and the walls are coated with a phosphor. Conductors are connected from the contact base to the quartz burner, and two limiting resistances are connected to two additional electrodes.
Lamp Features
Manufacturers claim that the life of such lamps is ten thousand hours. In fact, due to wear of the electrodes and phosphor, it is several times smaller. At the same time, the quality of the luminous flux of the “DRL 250” lamp almost drops by half — in this case, the lamp must be replaced and disposed of.
Due to the fact that the inner part of the flask is coated with a phosphor, the ultraviolet light generated inside it is converted into a spectrum of illumination visible to the human eye.
Inside the quartz burner generating the working arc, there are electrodes - the main working elements - in the amount of two or four pieces, closed by an additional glass casing. They are often made from tungsten, but other metals can also be used.
Inside the glass tube, not only pure mercury can be added to argon, but also substances similar in properties to it.
How the DRL 250 lamp works
The luminous flux created by this lamp is generated according to the following principle.
The direct current supplied to the bulb through the electrodes enters the starting mechanism - the starter, creating an electric discharge. The voltage of such a discharge at the time of switching on can reach several kilovolts. The tasks of this part of the circuit also include stabilization of work after ignition of the lamp.
Due to a strong voltage jump in a gaseous medium, an electric arc (breakdown) occurs and ignites it. The continuation of the process is the conversion of a drop of mercury into steam, which, interacting with argon, emits ultraviolet light waves.
In turn, when it reacts with a phosphor, ultraviolet light begins to emit a part of the spectrum that is already visible to a person.
Due to the gradual heating of the gas, the “DRL 250 W” luminous flux does not immediately gain maximum power - this occurs after complete heating after switching on for ten to fifteen minutes.
Specifications
To understand what a mercury-arc lamp is, it is necessary to consider its technical characteristics:
- power consumption - from eighty (with a two-electrode design) and from two hundred and fifty (with a four-electrode) to one thousand watts;
- socle - depends on power: up to two hundred and fifty watts - E27, above - E40;
- the power supply clock load should not exceed eight amperes, depending on the power of the “DRL 250” lamp;
- luminous flux, lm - devices produce high-intensity lighting from three thousand two hundred (eighty watts) to fifty-two thousand lumens (one kW);
- declared service life - from ten to twelve thousand hours;
- mandatory use of a starting device.
Pros and Cons
Speaking about lighting devices of this type, the following advantages of DRL 250 lamps should be noted:
- the luminous flux is quite intense, has a good brightness;
- durable in work;
- suitable for outdoor use, as they withstand low temperatures;
- due to their high power, they are suitable for use in large rooms.
Among the shortcomings are the following:
- switching on with a certain delay and reaching the desired illumination only after some time;
- continuous buzz of lamps "DRL 250";
- luminous flux gives poor light transmission low-quality light;
- the presence of a high coefficient of flicker;
- installed at a height of at least four meters.
Health Check
If the lamp was connected, but did not start working at all or does not work correctly, then this is an occasion to test the device to identify the causes of the malfunction. For these studies, special instruments are needed - an ohmmeter or tester.
Using these meters, the integrity of the winding turns is checked for a break or for a short circuit arising between adjacent turns. If there is a gap in the circuit, the device will show the wrong value due to the infinitely large resistance. In this case, the winding is completely replaced.
If there is no gap, but insulation is lost and a short circuit occurs, the device will show a slight increased resistance.
If a short circuit occurs in the throttle winding, the resistance will practically not change and will not affect the lamp operation. In this case, there is a high probability of a malfunction of the bulb itself or the power supply system.
Similar light sources
Innovative LED-luminaires with increased power (from twenty to one hundred and fifty watts) can be considered a full replacement for "DRL 250" lamps. The luminous flux of the LED analogue is characterized by excellent color reproduction of the illuminated object and low heat transfer.
In addition, LED lamps have the following characteristics:
- increased energy saving;
- Efficiency is almost ninety-eight percent;
- resistance to temperature jumps;
- well withstand mechanical stress;
- insensitive to voltage drops;
- no flickering effect;
- large stock of working hours;
- environmental friendliness.
In order to assess the illumination of a room for comparing LED lamps or “DRL 250”, the luminous flux in lux must be measured with a special instrument - a luxmeter or calculated using the formula as the ratio of luminous flux from the characteristics of the lamp in lumens to the illuminated area.
Thus, it can be seen that if seventy square meters are illuminated by a lamp with a luminous flux of two thousand eight hundred lumens, then the illumination of this quadrature will be equal to forty lux. This corresponds to the use of two hundred-watt incandescent bulbs.
Scopes of application, nuances
Technical characteristics of lamps of this type allow their use for lighting:
- open production sites;
- car tunnels;
- railway platforms;
- parking lots and bus stops;
- construction sites;
- large storage facilities;
- parks and squares;
- playgrounds and courtyards;
- pedestrian crossings;
- production shops, premises of plants and factories;
- agricultural and livestock complexes.
Most of all, such lamps are suitable for lighting open spaces, rather than rooms.
In addition, it must be remembered that DRL 250 lamps, the luminous flux of which is created using mercury, must be handled very carefully. If a quartz bulb is damaged, the expansion of mercury vapor indoors is twenty-five square meters.
Four-electrode lamps should only be connected via a choke - a current limiter corresponding to the lamp power. Otherwise, from a large electric current, the device instantly burns out. And if you include a non-electrolytic capacitor in the connection diagram, you will be able to save about two times the energy consumption.