Hello friends, today I am going to tell you that the structure and working of mercury vapor lamp – structure of mercury vapor lamp, working of mercury vapor lamp, use of mercury vapor lamp: If you also want to know then read this article completely.
Structure of Mercury Vapor Lamp
The inner tube of a mercury lamp also called an arc tube, is made of quartz. This tube has tungsten electrodes on both sides. A few milligrams of mercury and about 25-50 Torr pure argon gas are filled in this tube. Since there is a large distance between the two main ‘electrodes’, the ionization of the filled gas does not occur due to the low voltage gradient in the arc tube. Hence a starting electrode is placed near the main electrode as shown in the figure. Therefore, initially, the entire voltage is applied between the main electrode and a starting electrode, due to which a sufficient voltage gradient is generated between these two electrodes, resulting in ionization of the gas. When the gas discharge starts, a lot of current flows, so to control this current, a register is installed in the series of the starting electrode.
The outer tube of this lamp was made of borosilicate. This tube can be transparent or the inner surface is phosphorus coated. The phosphorus-coated outer tube converts ultraviolet light into visible light. The outer tube is filled with nitrogen or argon-nitrogen mixture, or sometimes with carbon dioxide so that the arc tube does not oxidize and phosphorus does not decay.
The outer tube of a low-power lamp (less than 50 watts) is filled with vacuum or argon gas because there is less heat loss. Platinum or gold is coated on the back of the electrode to prevent heat loss in cold environments. A choke is required to control the current in a mercury lamp. Its circuit diagram is given in the following figure.
Working of Mercury Vapor Lamp
When the lamp is turned on A.C. When a supply is given, a gas discharge starts between the main electrode and the starting electrode, due to which the ionization of mercury starts and a dark blue glow is generated. Because at this time the gas pressure is very low. Gradually, due to gas discharge, heat is generated and ionization of mercury occurs rapidly, due to which the gas pressure increases and ultraviolet light is converted into visible light and white light is produced. Lamps that do not have phosphorus coating, their light is greenish-blue when fully illuminated. These lamps are mounted vertically because if they are used horizontally, the gas discharge arc will touch the tube causing the lamp to fail. Mercury lamps that are mounted horizontally are fitted with a magnetic object so that the gas discharge column is centered. This lamp takes 3 to 4 minutes to fully illuminate. The temperature of its arc tube is 600°C in case of lamp burning. Their efficiency is 30-40 lumens per watt. These are made of ratings of 250 watts, 400 watts. This type of lamp is called the MA type. This lamp is AC work on.
Apart from this, there are MAT-type mercury lamps. These are made of ratings of 300 watts, 400 watts. AC them and D.C. Can be used in both. Chokes are not used in these. The outer tube of these lamps is not vacuumed and the filament is connected in a series of arc tubes that acts as a ballast. When this lamp is connected to the supply, it acts like a filament lamp. Initially, the entire output light is received by the outer tube, at the same time the arc tube starts heating, and at a certain temperature the thermal switch works, which cuts off some part of the filament, so that the discharge starts between the electrodes of the arc tube. goes. It has a power factor of 0.95 so it does not require a capacitor.
Low watt (80 watts, 125 watts) lamps are of MB type. In these, high vapor pressure 5-10 Atmosphere is used. They work similarly to MA-type lamps but with a higher resistance added across the range of the starting electrode. Their outer shell is made of quartz.
Uses of Mercury Vapor Lamps
- They are used in street lighting and industrial plants and commercial places and institutions.
- They are used in Railway Yards, Ports, Shopping Malls.
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Now you must have come to know that the structure and working of mercury vapor lamp, the structure of mercury vapor lamp, working of mercury vapor lamp, uses of mercury vapor lamp.
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