4 most important questions for every electrical maintenance engineer

1.) If one lamp connects between two phases it will glow or not?

If the voltage between the two phases is equal to the lamp voltage then the lamp will glow. When the voltage difference is big it will damage the lamp and when the difference is smaller the lamp will glow depending on the type of lamp.


2.) Two bulbs of 100w and 40w respectively connected in series across a 230v supply which bulb will glow bright and why?

The two bulbs are connected in series they will get an equal amount of electrical current but as the supply voltage is constant across the Bulb (P=V^2/R).So the resistance of 40W bulb is greater and the voltage across 40W is more (V=IR) so 40W bulb will glow brighter.


3.)  What happens if we give 220 volts dc supply to bulb or tube light?

Bulbs or any other devices or equipment which are designed to operate on AC supply, such that it offers a high impedance to AC supply. Normally they have low resistance. When DC supply is applied, due to low resistance, the current through lamp or tube-light would be so high that it may damage the bulb element.


4.) How can we start-up the 40w tube light with 230v AC/DC without using any choke/Coil?

It is possible by means of Electronic choke. Otherwise, it’s not possible to ionize the particles in the tube. Light, with normal voltage.

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