Electrical Engineering Interview Questions

if two transformers are placed parallel & both have fault impedance of 50KA will it increase or decrease show example?

711

How many points does a Circuit can have?

732

if two transformers are parallel & both have fault short ckt. impedance of 50KA in each case will it increase or decrease show example?

1631

How many points can we have in AC Circuit? Show by giving suitable example?

2671

-----------means a source which can supply a constant voltage to aload irrespective of the valu of load resistance.

2284

will there be any problem by recovering slip from single phase induction motors?

672

What is the electrical difference between Earthing Switch (ES) and Maintenance Earthing Switch (MES)?

1146

how we calculate the knee point of a protection and metering CT and what is the testing procedure.

CS,

2235

HOW WE KNOW IN PHYSICALLY THE CONTACT SURFACE OF A VACUUM INTERRUPTER IS GOOD OR GOING TO DAMAGE IN A VCB AFTER ABOVE 500 TIMES OPERATED.

825

What is a LBB protection and why it is used?

6017

what is a starter ??

NPTC,

2574

what main difference betwenn invetter & ups & major difference

ABB,

4373

Dear sir, I am working in wind mill division , pls explain Pls explain in details with formula My question is Wind speed 3.5 M/s Gen RPM is 1500 ( 25 K/w Production ) Wind speed 12 M/s Gen RPM is 1500 ( 220 K/w Production ) Why in 3.5 m/s generation was low , why in 12 m/s generation was high , Pls dont explain wind force or wind density , that one already i know For the above question RPM was same why the KW was different Answer : 1. Its depends on the density ( Force ) of the air Sir , Pls explain wit Formula sir

1762

why stay insulator is not used with stay wire for 11kv Lines. Whereas it is used for LT lines ?

9965

Why are cables rated for 40 KA for 0.25 Sec fault current rating?

706

Un-Answered Questions { Electrical Engineering }

what is invertor supply and raw powersupply

763

-What should be minimum value of insulation resistance and maximum value of earth resistance at any electrical instillation and what is method of testing the same.

819

Dear all, I just want to ask an expert on this forum for some insights. For the magnetic balance test, when applied voltage on a Delta-Star transformer e.g. Dyn11, the following relationships apply for HV side: 1.  H1-H2 = H2-H3 H3-H1 2.  H2-H3 = H3-H1 H1-H2 3.  H3-H1 = H1-H2 H2-H3 For the LV side also: 4.  X1-X0 = X2-X0 X3-X0 5.  X2-X0 = X3-X0 X1-X0 6.  X3-X0 = X1-X0 X2-X0 Is there a similar pattern for Y-d, Y-Y, D-d? And how about Y-z, D-z, Z-y transformers? I've tested a YNzn5 transformer and for LV side I don't see the pattern. In this particular case I got for LV side the following (see values below): H1-H0  H2-H0  H3-H0    X0-X1  X0-X2  X0-X3 128.0  119.9  7.2      29.2   13.3   15.8 70.7   128.4  59.2     23.4   22.0   3.6 7.2    120.1  128.1    13.4   29.3   15.8 What is the relationship here for LV? For row 1 I see the relationship, for row 3 I also see but it's shifted, but for row 2 I don't see such relationship. Any suggestions, answers, someone?

586

while doing high voltage test on 11kv/433 distribution transformer why we only give 28 kv on hv side and 3kv on lv side for power transformers what is the value what factors it depends

1306

Electromagnetic torque developed by the motor is compared to shaft torque. A less B same C depends on motor design D more

761

Explain the operation principle, advantages and disadvantages of the following converters: a) A 12 pulse converter b) A Switch-mode inverter c) A thyristor inverter

731

How PSV sizing being done

921

how to Select Lighting arrester? What r the parameters to be considered for the selection of Lighting arrester ?

469

Batteries. What is the difference between Lead and Nickel batteries ?

912

For the requirement of a furnace of temperature range up to 1200 oC using silicon carbide rods, What is the required rate of transformer needed (please do it with all details)?

779

Explain Circuit Breaker Trip Characteristics in detail.

791

How to Calculate Current Rating of SDFU (Switch Disconnector Fuse unit) for Protectionof Capacitor Bank connected to Busbar of 800Amp,in LV side of 11/0.433KV, 250KVA Transformer?

3075

R=*¶ l/a

407

how can i use REF and diffrencial relay both in 1 CT core for transformer protection?

569

Can double compression glands be used with regular cables?

839