Answer / nithya

by using megger.

Answer / gajendra singh

earth resistance is measured by a magger.

Generally transformers has delta primary and star secondary. But in some transformer i saw Star primary and delta secondary. what is the reason for chosing like this?

2 Answers  

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why is a power transformer used only occasionally?it is used to step up at generating stations?and that needs to be done all day long !!!!!!!

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What is the formula for selecting the cabels according to load? How to calculate what sq.mm cabel to be used?

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if we have 320KVA Genset kindly advice how much load we can put it.

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Energy metering: On the property I am renting, the supply voltage is 2 x 110 volts. These 2 x phases enter a energy meter which then exit the meter to over head lines to my house. Question 1. The meter is single phase 240 volts but is being used as 2 x phase(2 x 110volt), is this acceptable? if not, please give me the reasons. The meter details are as follows: 60Hz 15amp Imax 100 amp Kd 3,6 Wh/R 1 fase 3 hilos Model FX 231. I think it was manufactured in Brasil From this meter, the cables run along over head aluminum conductors,I estimate the cross sectional area to be 25mm diameter, but the neutral is only about 10mm square diameter, which cover a distance of 170 meters and then terminate with an underground cable of 65 meter length, total length = 235 meters. There must be a huge voltage drop over this length. This line is protected with 2 x 200 amp aluminum fuses after the meter, there is no main switch in the distribution board. These 2 phases connect directly onto 2 busbars. Surely the neutral should be the same size as the conductors if not more? Question2. What are your thoughts about this installation, should there be better protection, is the neutral too small? During the night, the lights dim then brighten all the time, this cannot be good for my electrical appliances. In my home, I only have a small electric geyser and fridge, my stove works off gas. But when i use other appliances like the washing machine or microwave oven, the light dim. The internal wiring of this house is done with solid hard drawn copper wires and of course, they have to be under rated. I am a retired electrician by trade, but not on the metering and over head mains side, my experience is on the factory maintenance side of things. Your expertise on these matters will be greatly appreciated. Please inform me how to rectify or make any improvements Kind regards, my power bill is very expensive, so I need to know how to bring it lower. Kind regards, Brian

1 Answers  

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what is the advantage and disadvantage of billing in kwh and kvah by electricity board .

6 Answers   Nespak, NTPC,

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what will happen if we will not use commutater means if we will give dc to the windings in dc motor

1 Answers  

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is emf is indued if dc is passed through coil

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what is ups?how its works?and what is there in static switch how it works?

2 Answers   Bhel,

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why the Current transformers secodary is shorted to ground (In metering and Protection)

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I did oil BDV test of 1600 KVA trafo 20KV/400V as per IEC 156. Result is 1) 58 KV 2) 58 KV 3)40 KV 4) 50 KV 5) 58 KV 6) 18 KV. Avr is 47 KV. Can we say oil is still ok even in the 6th test BDV is 18 KV ?

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as we see that in our country the power rating for transmission is always rated in multiple of 11 like 11kv,33kv,66kv132kv. So i want to know wht is reason or logic here.

2 Answers  

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