Page 334 - Electrician - TT (Volume 1)

ELECTRICIAN - CITS

Mat type HPMV lamp
This is similar to MA type, but outer glass envelope consists of tungsten filament.
This filament is connected in series with discharge lamp.There no need of external choke and capacitor.
When the lamp is switched ON,it works as filament lamp and its full output is given by the outer tube.At the same
time,the discharge tube starts warm up,when a particular temperature is attained,a thermal switch operates.The
thermal switch cuts off a part of the filament so that the voltage across the discharge tube increases.
The light output is a mixture of light produced by filament lamp and discharge lamp

Mb type HPMV lamp: The discharge tube of this type is of quartz,about 5cm long and has three electrodes,two
main and one auxiliary.This lamp has a 3-pin bayonet cap and it cannot be put in to an ordinary holder as it
requires a choke and capacitor.The functioning of the tube is similar to that of a MA type lamp.Since a quartz tube
can withstand high temperature,it can be used in any position
The wattage available are80W,125W,250W,400W,700W and 1000W.The efficiency is about 50lm/W

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CITS : Power - Electrician & Wireman - Lesson 54-59