Electrical Interview Questions
1) why transformer cannot rotate though the principle behind induction motor is similar to a transformer
2) WHY THE +VE POLARITY OF 48V DC POWER SUPPLY IS USUALLY GROUNDED
3) what are the types of control panel used in industries & all electrical purpose
4) suppose we using 3 phase motor of 440 v means what range of C.T. is require for measuring current , the rating of motor is 1HP
5) What are the differences between ELCB and RCCB
6) will the turbogenerator operate on leading power factor with out modification in the stator winding
7) i want to know is it possible to generate usefull power by coupling generator with motor & supply gives to motor by battery source then generator generates power. remove the battery source given to the motor & feed the supply from some of the generated power supply to the motor & motor runs continously. generator generate power contnously.is it possible ?
8) Inductor and capacitor........power in one phase and ...... in it another phase
9) Iam deepthi.i completed my b.tech from electrical engineering.i want to prepare for civil services.i dont have much knowledge about these exams,but i have great zeal of cracking exams.plz provide me suggestions to which options i can select for optionals
10) suppose we using 3 phase motor of 440 v means what range of C.T. is require for measuring current
11) How we can calculate the Amps for the cable Ex:- For 1sqmm wire how many amps we can draw (calculation)
12) what is the meaning of bus? 2. what is the dc transformer? How it work 3.what is the function of the serge absorber? 4.How the CT and PT rating calculate/
13) what is bus pt and what is the function of it
14) i have applied for the post of RRB section engineering chennai board please send me previou papers and solved answer. my mail id jagarapusrinivas@gmail.com
15) what is two wattmeter test
16) we have 3 single phase transformers. how will we generate 6 supply from 3 phase supply input
17) protection used for alternator , feeder , transmission line
18) what is merz price protection
19) what is rise time and half time
20) what is surge impedence loading
21) i have three phase 25kva transformer but there is two phase line how can i connect to the two phase line
22) What is RTCC panel and why it is required
23) What is the difference between a 3 winding and 2 winding Potential Transformer
24) how we can calculate cable size for any load & any type of cable material
25) why transformer ratings are taken in 11kv 22kv 33kv but not in 10,20,30kv
26) Why generally the Rating of Transformers are in additions of 11 i.e. 11 kVA, 22 kVa, 33 kVA, etc
27) Is there any problem ,if R-Y-B voltage is constant , but the air compressor taking one phase high current.what is possible causes.the said compressor is very new.(55kw)
28) Inductor and capacitor ........ power in one phase and ...... it in another phase. if any body found this gaps answer.please sent me to habib_eu2008@yahoo.com
29) CAN ANY ONE EXPLAIN THE KNEE VOLTAGE OF THE CT
30) can u tell the difference between star - star transformer and delta to delta transformer
31) We have received supplies of the ordered material. payments against the supplies also released. Where ST paid 4% against form C. Meanwhile it has been observed that 25% of material supplied was defective. Please suggest whether the issuance of C form from our side would be stopped till settlement of liabilities
32) For R-L or R-C ckt,time constant formula is L/R and RC respectively and its unit is in sec.Pls tell me the derivation
33) what will happen at the time of CT saturation?and what will be the Relay's function at the time of CT saturation?
34) Tell me about yourself. ……………………………………. Why did you leave your last job? What do you see yourself doing five years from now? Ten years from now? What are your long-range career objectives? Why did you choose this career? How well do you work with people? Do you prefer working alone or in teams? How would a good friend describe you? What would your last boss say about your work performance? Why should I hire you? What makes you qualified for this position? What do you think it takes to be successful in a company like ours? In what ways do you think you can make a contribution to our company? What's the most recent book you've read? What two or three accomplishments have given you the most satisfaction? Why? Describe the most rewarding experience of your career thus far…………… Why did you decide to seek a position in this company? What can you tell us about our company? What do you know about our competitors? What two or three things are most important to you in your job? Are you willing to travel for the job?
35) what is open star connection or open delta
36) How to determine the breaking capacity such as break down current and break down voltage for VCB and CT's.
37) How to determine the short circuit current for breakers and VCB
38) what is meant by mimic diagram ?where it is used ?plz explain briefly
39) Which ciass CT can be use in diff. protection. Can be use 5p20
40) why generator and t/f ratings given in kva & motor rating is in KW
41) Why birds seating in HT line does not get shock? If person hangs in HT line (single hand or both hands) does he get shock
42) How much kv gas generator is needed to run 2 hp and 1 hp airconditioners, plus a refrigerator and 4 Tvs
43) What is the function of stater in tube light circuit
44) What is rotating magnetic field?Discuss elaborately
45) What is the working principle of ceiling fan
46) difference between shunt coil and tripping coil
47) Can anyone explain me about the capacitor calculation
48) What is the exact load current needed for a place which has 100nos of bulb of each 100w
49) How you calculate the repturing capacity of a HRC fuse
50) what is the rating of boiler
51) what is the diffrence between dol and star delta strater? why star delta starter used instead of dol
52) why generator and t/f ratings given in kva
53) what is the diffrence between kav and kvar
54) why in electric train we can't feel current & generally we have get socked in our normal electricity
55) in ring main system we use the isolater b/w transfer bus and main bus if we r not use isolatar than wat will be the effect in our sys
56) What type of fittings and electrical accessories can be install in radiation area
57) what are the effects on an power plant and consumers if the power factor is increased or decreased
58) what is the calculation method to design core and winding of a 200kva 3phase distribution transformer
59) I am having dual speed motor of cromton greaves make of 3.7 KW -1400 rpm and 5 KW - 900 rpm. Please let me know groups and winding connction for rewinding purpose
60) What is the maximun current carring capacity in per phase for three pole 100anps rating ncb
61) have seen one 8.4 MW synchronous motor in a plant located in bellary it is fixed with brushless rotary rectifier ,anybody can explain its start up principle
62) Need help. 3 phase system. Neutral line arced and melted upon connection of connector with 3 phase power. Why would that happen?
63) Dear sir, In our plant have Station Transformer having capacity,i want to know, why LV side 40 - 40MVA is given? & how we can get 6.3 KV supply from tertiary(i.e. Open delta connection), Vector Group YNyn0 - yn0 +d MVA Rating 80MVA / 40 - 40MVA + 26.7MVA Voltage rating 420 (Tap range +6,to -10)81.25% /11.5KV - 11.5KV +6.3KV
64) what will happen if a cw rotating altenator being synchronized to ccw rotating altenator
65) explain why tap changer is always connected to high voltage winding side of the transformer.
66) explain why the secondary terminal of current transformer should not be lift open circuited.
67) While testing the value of the resistance for the earthing rod, two auxillary rods are connected to the earthing tester.What is the working function of a earth tester?
68) please forward me the type of questions which would rise while me attending to 33KV Electrical License to my mail ID:vadrevu_raghava@yahoo.co.in
69) if 300 hrs not comleted at wat interval b.c,d checks og take place
70) what is the formula of knowing the clabe size on any load?
71) If excitation will increase, then what will be the effect on power factor? Will it decrease or increase?
72) how to measure the current by compact digital equipment with dislay which fit inside any equipment
73) How to test Power Transfomer vector group?
74) n UPS what does 600va reffer to?
75) Why do power lines not short out when they fall into water
76) expansion of rccb
77) How the CT and PT ratings are calculated
78) What is harmonics and how the 1st,2nd,3rd etc harmonic levels
79) how we calculate the 30 KW 3phase electric motor current on noload
80) which type of starter is suitable for single phase motor
81) how is working d.c amps meter?how to connect the dc ammeter inthe circuite
82) Why dose an electric meter record KVA when there is no load on a 500 KVA transformer
83) what is the ambient temperature of transformer oil & winding?
84) why breather cap filled with oil?
85) Isi standard of lux level required / to be maitained in different working place general & in textaile industry
86) s it necessary to seperate the DG earth grid with Electricity Board earth grid for protecting the DG set. if yes why?
87) Basic philosophy of applying 3P tripping for uptill 132KV switchyards & for 132KV & above 1P/3P tripping is used
88) what is the working principle of smoke detector in fire alarm system
89) IN 1000kva transformer where the oil and winding temperature sensors is connected
90) why we avoid parallel operation of diesl generator
91) can any one list the class-a, class-b & class-c trips of power generator
92) MCB Rating
93) How do you protect your appliances from harm in case of neutral failure in a three phase power supply set up
94) What is the function of a turbo charger in a 1000kva DG set
95) which protection used in power plan
96) why bucholtz relay placed inclined in transformer
97) why semiconductor fuse used in drive ,not ordinary
98) Meaning of CTPT ,how it works &how it measures the reading on trivecter
99) meter,&what is trivecter meter
100) What is the lifetime of a Thyristor? Is there a recommended lifetime for thyristors after which they should be replaced
101) WHY DISEL GENRATOR SET SHUT DOWN IN OVER LOAD CONDITIONS
102) in gen traf what is ONAN , ONAF , OFAF and DYN
103) what is bus duct and what is differance between bus duct and bus bar
104) Single line diagrams for star to delta and DOL starters
105) Signal transmission in sky wave propagation is due to ? a) Reforction of wave b) Reflection of wave c) Pierus through Inosphere d) None and Reason for this is????
106) The transmission does not have options: a)Partition noise b) Flicker noise c) resistance d) Short noise and reason
107) what r substations?what r there work?why voltages r incresed and then reduced during distribution of power
108) explain how the power is distributed from a power plant to a consumer.explain step wise in detail
109) what r Grid stations?what r there role. Explain in detail
110) What is an Air Compressor
111) Please clarify 1. Icw: rated short circuit working withstand capacity 2. Icu: Rated ultimate breaking capacity 3. Ics: Rated service short circut withstand capacity 4. other specification of ACB
112) What is the field weakening mode of a ac motor?
113) What is polarisation index value?.(pi value) Simple & brief definition of polarisation index
114) how can we decide where we have to DYn11 or other vector group transformer
115) how can we decide where we have to DYn11 or other vector group transformer
116) Can 4pole (3 phase+neautral )RCCB proper functioning in only 3 phase load (no neautral, no Earth
117) I WANT YHE TECHNICAL AND ELECTRICAL SPECIFICATIONS OF 2x4MW 11KV 2x10MW 11KV 2x25MW 11KV 2x100MW 11KV HYDEL POWER PLANT i.e PROTECTION SYSTEM,MONITORING,CONTROL SYSTEM,GENERATION,SYNCHRONISATION,METERING PLEASE
118) please tell me the all the spcications of the 100MW 11KV HYDEL POWER PLANT SPECICATIONS
119) how to match 0 -10V with 4 – 20mA
120) What is Earthing
121) what should we do when the CT secodary gets open? how do we short circuit it? using tester or screw driver? not dangerous
122) how you configure motorvision relay (L&T make)from DCS
123) can we connect both delta and star to the transformer secondary and for what reason?
124) which pump is suitable for home use ?
125) what is MC 61 relay
126) How can I calculate the fault level of a transformer. 1. If fault is 3phase fault 2. If fault is 1phase fault 3. If fault is 2phase fault Dear all geniouses, can you help me by giving answer.
127) role of europe union in UK safety legistlation (electrical safety)
128) wat is the criteria we use the diff. Relay
129) how to set the time in digital timer
130) Why A.C. capacity given in Ton. Ex. - 1.5 Ton
131) How to calculate the size of window A.C. for 200 Sq. ft room
132) How can we find out LT UG cable fault (size,from-4*25mm sqr to 4*300mm sqr)? How mani types UG cable faults
133) What is the Polarisation index value ? (pi value)and simple definition of polarisation index
134) How many types of lightings are there
135) how many types of ratings are there of transformer
136) i am working in automation feild my question is that how to find the KVA of transformer
137) what is the advantages of having in-built acvvvf (without seperate inverter in the control panel)in the drive system of elevators
138) if we convert ampers into kwh or mwh ,which one formula use by us,pls tell me
139) iam working in power plant. In hot places tube lights are glowing at the end portion only. what is the reason for that
140) How to arrange a hous hold earthing system to keep minimum earth resistance( below 7ohms)
141) which stabilizer is better ? AVR, Servo Stabilizer, Static stabilizer etc & why explain it
142) what are the main faults that occur in stabilizers? How they corrected and resolved ? Types of stabilizers ?
143) How to arrange a hous hold earthing system to keep minimum earth resistance( below 7ohms).
144) What is the recommended voltage gap between Live and Earth and ,Earth and Neutral.If these are exceded what is the solution.
145) what are the breakdown voltage rating of mini- curcuit'transfarmer
146) can mini-curcuit supply MIL-tested transformer
147) i want to learn control schedule for 11kv panel? can any one send the detailed control schedule
148) What kind of battries are generaly used with Disel Generator
149) How does a television work
150) keeping in view of parallel operation which of the 3 phase transformer connection are possible? a)delta-delta to delta-star b) delta-delta to star-delta c) star-star to delta-delta d) delta-star to star-delta
151) what is th basic difference between a d latch time line and a d flip flop time line
152) what is the meaning of WYE and DELTA in Electric meter
153) Please help me.What are the difference between two wire, 3wire, and 4 wire in electric meter
154) what is the difference between single phase, 2 phase, and 3 phase in electric meter
155) what is 3 phase motors
156) what is 2 phase motor
157) what is single phase motor
158) What is the difference between single phase, 2phase, and 3 phase motors
159) what is power
160) how calculate the current faut level
161) advantages of vvvf drives over non vvvf drives for EOT cranes
162) what is the thumb rule to know current carrying capacity of copper conductors of different size
163) why the difference arise between HT reading & LT reading (submeters fixed in complexes, apartments etc)if the power factos exceed from 0.9 to 1 can the ht meter reads fast
164) where this neutral connection goes after returning from the load(home ,factory,industries).Is it grounded at the transformer side or atthe generator side .If it is grounded then we also ground the earth connection.is there any problem with this
165) why protection and metering CT's are always connected in star why not in delta
166) why we are used D.c. voltage in L.T.side or controling side.we can use UPS also ,in place d.c. Voltage
167) why we r used APFC Panel in industrial area.when P.F. low then wat will be the effect in our system
168) WHY FLEXI LINKS ARE USED INBETWEEN GENERATOR TERMINAL OUTPUT & BUS DUCT CONDUCTOR
169) How i can decide that HVDC line is best for transmission.
170) Can u tell me design of switch yard
171) How many types are using in 220kv/400 kv swith yard
172) What is fuction of NGT/NGR using in Generator
173) how does the rotating m.m.f is produced in the 3-phase induction motor and how the poles are created in 3-phase induction motor
174) What is the meaning of CT 40/5, 100/5 or in HT lines 100/1
175) How to calcute the cable size for both HT and LT please specify the formula for that Regards Chethan C
176) generally on the roadside v hav 11kv line which is being step down to 440v line to line....so any1 can tell me which type of transformer they r using whether it is star to delta,delta to star etc.
177) what is the order of mgnetiation current in a current transformer of 1000A/1A ratio
178) why 3 phase is preferred than 1 phase
179) can any one suggest websites having study maetrials for the electrical students
180) why dc current is supplied in america rather than ac
181) What is the difference b/w Earthing and Grounding
182) whats the one main difference between UPS & inverter ? And electrical engineering & electronics engineering
183) what are the differences between 'exhaust fan', 'heavy-duty exhaust fan' & 'super heavy duty exhaust fan'. what are their power ratings
184) wat is the purpose (or)function of regulator
185) wat is the purpose of stabiliser?
186) wat is the advantage of induction motor
187) wat is diffrence between 1-phase and 3-phase induction motor?
188) what is meant by magnetic flow meter ? explain its working principle
189) What is surger vector in 33Kv transmission feeder
190) We have AC power generator of 8MW which is paralleled with 33Kv EB grid. Some times our HT breaker gets trip off due to surge vector problem. How to over come it? Is there any device to observe the surge and avoid tripping
191) If a surge divertor is required to be protected by 32 amp C Curve Circuit breaker does this limit the amount of protection from surges that you will achieve
192) what is nuetral grounding
193) what is field flash
194) how to diffrentiate between ac & dc motors from a distance
195) Motor and transformer working with same principle so why motor rotates while transformer not
196) what is impedence (Z) of transformer, what indicate in transformer , which perameter indicate in transformer
197) BRIEFELY EXPLAIN MEGGAR PRINCIPLE
198) EXPLAIN THE WORKING OF SERIES REACTOR IN HT CAPACITOR BANKS
199) WHAT IS THE USE OF ANTIPUMPING CONTACTOR IN HT BREAKERS
200) HOW CAN YOU CALCULATE PRACTICAL EFFICIENCY OF A ASYNCHRONOUS INDUCTIONMOTOR OF 7.5KW,& MOTOR IS RUNNING WITH AVOLTAGE OF 410 VOLTS,& TAKING CURENT OF 13 AMPS
201) give me a clear defination of inductance,and how can u calculate inductance of a motor
202) what is the effect of leading power factor
203) how external lighting design? please give example
204) what is the use nuetral wire
205) Why 60Hz frequency is used in America what are all the benefits
206) how we protect the motor & what are the components required for that
207) what is the use of earthing.
208) What is the difference between INVERTER and UPS
209) In 90 kva alternator that produce the output voltage is 115(p-n),200(p-p) at 1500 rpms means what ampere it produced
210) Suppose the incoming power is 11 kw, but the load require only 8 kw means how can we save or use the excess power
211) The potential difference between a phase and neutral is 230v , but the potential difference between two phases is 400v. Why
212) what is the importance of Partial Dischage test for Electrical Equipments
213) What is the importance of Form B to state Electricity Boards
214) What is Ten Delta Test
215) if we use fuse in neutral what will happen
216) How can we calculate the rating of capacitor bank to be connected for a particular load(ex.100kw)to improve the power factor from 0.8 to 0.9?
217) what is the difference in MCB, MCCB, RCCB, ELCB, & MPCB (motor protection circuit bracker)
218) How to calculate the heat load for a electrical room what is meant by frequency
219) DG lube oil and waste oil how to dispose outside and there is any authorised vendors will be there for this
220) how to calculate optimum loading for transformer
221) IF THE LOAD OF TRANSFORMER IS GETTING MORE THAN ITS RATING,,,THAN HOW TO OVERCOME THIS PROBLEM? SUPPOSE THEE RATING OF TRANSFORMER IS 315KVA AND THE LOAD IS GOING BEYOND THAN THE RATING SAY AROUND LOAD: 352KVA... THAN HOW CAN WE SOLVE THIS PROBLEM WITHOUT DEDUCTING THE LOAD
222) why we oltc on hv side of tranformer only
223) motor and transformer working with same principle so why motor rotor was roted and transformer not roted
224) why ht motor connection in star
225) What is difference between Earthing, Ground and Neutral
226) when the size of the cable used for the ht voltage is 300sqmm then what is the size of the conductor of each Phase
227) whye the current increases in the motor when the load on the motor increases
228) explain supply side and demand side energy management with advantages & disadvantages
229) explain impact of tariff on energy management..? and what is ABT tariff
230) importance of reactive power management
231) differtiate between energy consevation and energy efficiency
232) what is CRGO Transformers
233) tell about gas insulated substation?which gas is used for that substation?above which rating we are used this substation?how we take maintenance in that substation?it means substation fully shutdown or live condition?if live condition means how?pls clear this things
234) the resistance of wire having length X M is R OHEM if i streched the wire to dubble length what will be the resitance
235) what is the type of winding connection( star or delta) in 1HP to 5HP motors. How to check the motor winding connections( star or delta) if not provided in the nameplate
236) Which supply is using for train AC or DC & what is the voltage
237) What is the meaning of In,Io & Ir in Circuit breaker? How to calculate
238) what is mean by power factor
239) In wat way the power compensation takes place when a statcom is connected in a transmission line
240) Application wise, where we should use AC motors and where we should DC motor
241) Why HT cable have only 3 core
242) how to calculate the powerfactor in induction motor having name plate details , for example 1 h.p motor 1.86 A 415 V how we can select MCB ratings according to Voltages, Curves
243) How Much Capacity of Diesel Genset is suitable for 20 no.s of 1.5ton AC's & Why
244) How can we calculate strength of copper hich is supplying electric power to heater and in it hold the heater also and what r all types of forces which is acting on it.
245) What are the functions of different Parts of Alternator
246) What are the different parts of Alternator and how it works
247) Can HT cable(11kv cable) be used for 415V, 700A requirement
248) Can we inject more current in ct primary paralleling 2 loading transformers/Injection kit at a time?let ct ratio be (5000/1A)(per kit rating 2000A range),i need to inject 5000A,if this cant b done means wat is d optional
249) WHY IN AC DRIVES,INPUT PHASE CURRENT SHOW UNBALANCE
250) What is mean by power factor
251) What is mean by hormonics
252) why D.C excitation is given to sunchronous motor
253) what is proper capacitor placement? How to evaluate capacitor size
254) What is EMC filter in VVVF Drive
255) What is D check in a Diesel generator for 1000kva DG
256) What is C check in a diesel generator and what are parts and what has to be done during the C check
257) why the frequency in india is 50 50HZ why we not select the o ther frequncy range
258) Why HT motors are connected in star
259) If we are importing real power & exporting reactive power then what will be the effect on our system
260) how we can save the power ? suppose the electricity board gives 11 kw , but the machine require only 8 kw means how we can save the exese energy
261) Relation between Sq.mm of wire and Its current carrying capacity
262) How to select KW/HP rating of motor for particular application? Is there any relationship od RPM
263) what is the relation between Sq mm of wire and its current carrying capacity
264) WHY IL=IPH IN STAR AND WHY IPH=IL/1.732 IN DELTA? WHAT IS REASON BEHIND IT
265) How to select HT/MV cable size
266) how to calculte capacitor range for single phase induction motors??pls tel
267) tell how current tranfomer works
268) what is the switching substation
269) what is gridrotor resistance starte
270) why transmission voltages are in multiple of 11kv
271) how tan-delta test is performed
272) what is earth-fault?when it occurs? to check where it occurs what type of test should we do
273) two generator runnig with parallel but only one NGR on And one off Why
274) if two bulb of 50w &30w apply in series having 230v the which bulb glow bright ,why
275) How to select the cable size for the given load ?Pls explain the Formulae
276) importance of air gap in transformer
277) In a three phase transformer(delta/star connected)when i touch one end of the bulb in any one phase and other end to earth..will the bulb glow or not..if not why?..i'm touching the bulb in star connected side
278) how will you determine the short circuit capacity of a network
279) if v r considering a 4000/1A ct,if v inject 1 amps in secondary core wat happens?(consider as 2 core ct,each for metering and protection)
280) what is the length of air terminal in lightening arrester system
281) Is there a possibility to use such a treshold voltage for the NMOS part of a CMOS circuit that during the switching it will start conducting only after the PMOS part will be already closed, by this eliminating the leakedge current? Please note, I'm not asking about the well bias in standby mode, but about the "antileakedge" measures during normal operation
282) What happen if we have run 415 V,50Hz designed motor at on 480V,60HZ
283) what is the highest transmission voltage in India till now
284) when motor taking high amp what happen
285) what is the material use in bus bar & why
286) what is the working of vfd drives
287) what is working of no & nc
288) what is the working of ups
289) tell me working of air circuit braker
290) what is amf panel & how it is working
291) what is the range of using dol starter & star delta starter
292) What is formfactor
293) what is the problem of generator over voltage.?except automatic voltage regulator card
294) How to select the rating of a CT used for REF protection
295) The rating can be of equal rating of Phase current or neutral current rating
296) ANY ONE TELL ME ABOUT generator synchronization panel panel to synchronise 3 gen of 250kva both automatic and manual. 2 gen output vol 415 3ph, 1 gen output vol 400 3ph SEND THE DETAILS DIAGRAM ON THIS EMAIL ADDRESS ayazleo@hotmail.com as soon as possilble best ragrds electrical engineer ayaz mahmood SAUDI TECH
297) What is the scale analysis for condensor of HVAC system
298) Is it mandatory statutory requirement of transformer oil filtration annualy despite oil is withstanding required dieelectrical strenth and all others parameters
299) What are the parameters of water ( Water quality )to be monitored in Centralised HVAC ( water cooler chillers )
300) Why DC weldings sets preffered over AC considering human safety aspects
301) what is the principle of motor
302) WHAT IS PRINCIPLE OF TRANSFORMER
303) what is principle of DG
304) what is the principal of braker
305) How to identify the whether its an isolator or Breaker in MDB
306) What is the difference between MPP, APP, Mixed Dielectric power capacitors? Which technology is superior in current scenario
307) in trains i have seen the terminal which is connected at the top of the train is positive .where is negative ? track? i dont think so
308) difference between ac and dc motor
309) why contactors are used ...? is contactors and relays are same
310) usually why bettery voltage are 1.5V, even if you open a 9V battery there are six 1.5V batteries in series. is it not possible to increase this voltage other than putting in series
311) define reflection method
312) If fault current is 52 kA then what will be the CT specification
313) what is AVR in alternator how its work?
314) why DG rating in kva
315) why DG battery blast
316) What happen while we measure the Current in Rotor
317) what is different the DOL Starter and Star Delta STARTER
318) What is the harm if we install primary side 11 KV VCB at a distance of one Km from the 11/3.3KV 12.5 MVA transformer through 11 KV cable
319) what is numerical relay explain its operation
320) WHY TRANSFORMERS ARE RATED IN 11KV 22KV 33KV Instead off 10kv 20kv 30kv
321) Why no-load primary current is very small as compared to full load current in transformer (as 1% of full load current
322) Why not LED burn after showing alarm,as Alarm volt is 11- 13,But LED is of3 volt,why it isnt Burn
323) When Alarm report at LED,Alarm volatge is 11-13 Volt But LED is of 3 volt.then why not it burn
324) How to convert from HP to BHP please explain
325) My requirement is 1VA,50/5A Current Transformer for Metering .If I select 15VA , 50/5A CT.Is there any possibility of Technical Problem
326) Why the capacitor are connected in Delta(Three Phase) for power factor improvement
327) will we get shock from dc
328) what is surge impedance loading and it's significant in power system
329) what is effect of brush shift in machine
330) Why arc quenching is used in Diode
331) Why MS rod or flat are used in stead of GI rod or flat in switchyard earth mat
332) what are the main parts of DG? explian thier functions
333) what is the means of dedicate earthing
334) what happen if position of GNA and MNA is changed in machine
335) low frequency protection why recommend
336) What will hapen if we run generator below 47.6hz frequency
337) why neutral can not used in three phase motor connection
338) Is it possible to power factor more than unity
339) why neutral used in three phase motor connection
340) Why the capacitor are connected in Delta(Three Phase) for power factor improvemen
341) why neutral can not used in three phase motor connection
342) Is it possible to power factor more than unity
343) if we want to increase the back up time of an UPS what should we do ? if we want to decrease the charging time of a battery/batteries attached with the UPS what should we do
344) how one can know the charging time, discharging time of a 12 VDC battery ? If i have a battery of 12 VDC , 4.0 AH , how long will it take to charge from a charger (power supply) of input 220 V , Output 15 V and output current of 3000 mA and how long will it take to discharge whether using or not ? How much backup will it give
345) what are fluorescent lamps (fluorescent fixtures) & what are incandescen lamps (incandescents fixtures) ? differences between these two
346) which type of A.C motor is used in the fan (ceiling fan, exhaust fan, padestal fan, bracket fan etc) which are find in the houses
347) although ckt breakers have taken the place of old fuse. But instead of it , these older ones are still used in the industries and homes ? why .... what are their advantages and disadvantages ? which one is leading and winning the race and competition
348) How one can check the charger of the mobile phone or any other charger .......... that is it working ? if , working is it delivering the required supply which is needed by the battery to charge properly
349) How one can say about a device (e.g: a light holder contains 20 or 30 L.E.Ds which glows when power supply is off, from which source they are getting the supply..... battery or capacitor) without removing and opening up its case
350) why we not connect the 12 V batteries in parallel to get the more backup supply for an UPS ? wheter off line or on line UPS
351) I am designing new project sub station with 220 kV / 11 kV, 40 MVA capacity. This project have many recifier sets, which can generate 3rd harmonics. Now I have to select vector group of This transformer. To minimise 3rd harmonics, what care should I take in selection of Transformer Vecrtor group? If it is Y-Y with open Delta tertiary then what should be the rating & voltage of Tertiary Winding
352) Define motor & pump
353) for 5KW resistive load can anyone please suggest me whether to go for UPS/Inverter or Generator depending upon cost calulations
354) wHAT IS THE DIFFRENCE BETWEEN EARTHED AND UNEARTHED CABLE (XLPE)
355) which type of motor is suitable for water suction pump
356) how we do Vector group ,magnetic balance and tap changer test in Transforme
357) What is the significance of vector grouping in Power Transformers
358) if d gen is 50kw,load is 60 kw,hw d gen ll supply d remaining power
359) suppose generator rating is 50 kw,load is 25 kw,hw much d generator ll generate?what about d remainin power
360) what happen if we give 220 volts dc supply to d bulb r tube light
361) which fault is severe and why?between lll fault and lllg fault which fault is severe and y?
362) n CDG type IDMTL realy O/L , E/F, O/C which are used for out going feedrs,on R-phase o/c element, Y-phase , e/f elecment and on b -phase o/c element will be connected . Why the earth fault on center phase only, why not on other two phases
363) what will happen when power factor is leading in distribution of power
364) I have 480V Single phase and I am trying to figure how big of a transformer (KVA's) and Primary breaker size I need to provide 200 Amps at 240V for a building
365) Transformer TTR test procedure
366) what the function breaker failure scheme, how is it operated
367) what purose of the double circuit transmission line phase of the line phase changed for circuit-1 for Circuit-2 R-Y-B B-Y-R
368) how to find impedance , mutual indatnce in transmission lines
369) what the purpose of transmited high voltage in over head lines
370) why Line voltage =1.732XPhase voltage what mean by 1.732
371) what is the diffrence between voltage and current
372) TO operate transformers in parallel, vector symbol of the both should be same.If one transformer name plate is not there, how can we conclude that whether the transformer is having the same vector symbol or not
373) Can any one provide the inspection procedure of MIMIC for VFD panel? Details: If someone wants to have a mimic in the VFD panel what are inputs considered for the mimic(like on,off,trip) whether we are able to add speed variation in the mimic(if so how can we get) and what are the parameters to be checked in the MIMIC during inspection
374) How to size a transformer which will supply power to 550kW,690V motor starting with VFD
375) Describe: Energy efficient motors
376) How to calculate total harmonic distortion level(THD) in VFD? and how can we reduce harmonics
377) what is the effect of power factor of machines in starting current
378) What is K-rated transformer? What is the use of it? What can be the size(pls provide calculation if possible) of K- factor transformer for 550kW,690V motor operating with drive Vfd
379) How can we calculate the capacitance of generator's
380) if the back emf eqution for dc motor EB=(QPNZ/60A) THEN what is the value of A for PMDC MOTOR OR how can dicide the value of "A
381) what is threshold voltage for a relay what does it exactly means ?whats its value in our indian transmission system say 11kv feeder RMU relay
382) WHAT IS DIFFERENCE BETWEEN idmt and instentanous relay? is idmt is used as back up protection or else?or when instantenous relay saturates IDMT will operate?
383) What is relation b/w Transmission Lines & Communication Line
384) 11KW Delta motor is taking about 44Amps in star and goes upto 70Amps in delta and trips OFF. The rated current is 26Amps. Application is for the blower. The motor takes ( no load without coupling impller ) only 2.5A and 5Amps in star & delta starter test.Need to know why its taking high current.
385) Different methods of Improving power factor,especially in wind sector
386) Why Batteries are rated as AH i.e AmpereHour,and its formula to converting AmpHour to Amp
387) Why 4 pole generator generates more power and 6 pole generates less power campare to 4 pole
388) How we can convert H.P into KW or Vice versa
389) how invertor convert the dc into ac give brif detail
390) Wtat is vaccum currcuit breaker.define with cause of used.and where be use it Devise
391) what are the major & minor faults that occur in an inverter and in UPS ? And how to repair and resolve them
392) What are the steps for Testing of 6.6KV HT Panels
393) What are the Steps for Testing of 20MVA (make:-CGL) Transformer? How many Test that we have to do
394) Which motor has high Starting Torque and Staring current DC motor, Induction motor or Syn motor
395) How can we find out earth leakage,(shock)in side the house?.. (with out ELCB
396) what is the earth resistance
397) what is the function of Choke
398) what is ASCR cable and where we use it
399) what should be the minimum rating for using HT Motors
400) what is interlocing and what is the purpose of this\
401) What is Biased Generator Differential Relay
402) What is mean by PID controller? And what is its Long form+
403) we have 1000 litre water tank,it located at 25m hight from ground level,the water level on 10m below from ground level.for fill the tank within 1 hour,how much of motor rating(HP) want to select
404) what are the energy savings methods that are existing in coal based power plant?
405) what is the difference between concentrated winding and Distributed winding in motor
406) Please tell me 1 ton = How many Kilowatt (Electrical)
407) why star point of motor shall not be grounded?
408) what is the meaning of ceiling voltage in Generator excite
409) Why thwe Direction of Rotation of a TABLE Fan & CEILING Fan are different
410) how to calculate the kw, Amps consumed by a capacitor, give me the formula for KVAr into capacitance,KVAr into KW & KVA, Amps
411) where we use stardelta starter and dol starter
412) How will you Physically differentiate A.C and D.C motor?
413) What is the working of AVR in AC generators
414) How to check the specific gravity of the two 12 V batteries connected in series to a 24 V UPS and inverter ? will we have to disconnect all the connections and turn off the UPS and inverter or not ? will we have to check specific gravities in each cell of the two batteries ? what is the name of the instrument that is used to check the specific gravity and whats the procedure to check the specific gravity with it ? Thanks
415) What are the difference between these terms ? e.m.f, voltage, potential, potential difference, current etc? what are the difference between these terms ? (electromotive force) e.m.f, voltage, potential, potential difference, reference potential, reference potential difference, current. How can i explain and describe these all terms in single line each and little more explaination too thanks
416) what is the ideal earth resistance
417) Why should we use the igniter in the sodium vapour lamp
418) Why are some relay circuts designed to have the ct current flow through the neutral instead of the phase wire, such as in some diff relays
419) what is the use of power factor ? where its applicable ?
420) why the motor running in delta connection ? it can be in star
421) what is the difference between KVAR & KVA
422) what is meant by power factor
423) .wat is the negative slip region in the motor
424) i m electrical diploma holder i want to do plc $ Scada some body tell me which insitute is best for me near chandigarh
425) What do you mean by Frame 5 Gas Turbine as well as Mark II
426) why transformer rated in KVA not in KW ? we know that W= v*i
427) what deffrence between KW $ KVA ?
428) Is it posssible to obtain the higher speed(3000rpm) for adiferentiallly cascaded induction motors(with 8 and 6 poles)
429) On load tap changer (OLTC) explode?
430) Transformer Vector group: Ynd11 Rated Power: 353MVA Rated Current: 693A Voltage:294/20KV OLTC Type: T III Y1000 110/c 12193w Max Operation Current: 295A Step Voltage: 550V Arrangement in Tx windings: Y Connection Problem: Damage of Unit 1 Generator Transformer On Load Tap Changer (OLTC) Description of Incident: 9.00 a.m. :- Generator No Load test on excitation system started 10.30 a.m :- Carried out AVR change over test 11.30 a.m :- Preparation for Generator Manual Synchronizing test 12.00 a.m :- Manual Synshronizing test started. Observed incoming generator voltage higher than running voltage. CECR operator operated Generator Transformer OLTC to bring down the incoming generator voltage 12.03 a.m Generator Transformer abnormal alarm operated at Gen.Control Desk (CECR) CECR operater at Generator transformer bay informed that the transformer oil splashed out from OLTC. CECR operater informed that he heard explosion inside OLTC. Observed Oil level & Oil Flow alaram operated at Tranformer local annunciator. 12.05 am :- CECR operator 'Open Gen Field Breaker” 12.10 a.m. :- Elec1 team inspected the OLTC and found the OLTC rupture disk was broken and oil spilled at OLTC area. - Elec1 found the OLTC top cover bulging. Do anyone know why and possibility cause happen in this OLTC
431) A three phase load, around 4 km away from the 11/0.433KV distribution transformer (Neutral of Transformer is solidily earthed) and consisting of mainly very costly and sensitive electronic equipments is giving trouble due to high voltage difference between neutral and body earth. Whether this problem can addressed by connecting neutral at the load point solidly to earth?
432) how many amps in 1 KVA? V=440v, PF=0.8 and FREQ=50Hz
433) what ll happen to current if two phases get short circuited
434) what is meant by earth fault and how it happens....
435) how to amps calculate from 1KVA?
436) how many amps in 1KVA?
437) what is the diff b/w HP and KW
438) how many percent setting of motor over load relay of its full load current
439) why transformer neutrol is grounding.
440) In industries Power factor is maintained by installing a suitable KVAR bank, How is the PF maintained for domestic use, where is the capacitor bank connected
441) what is the specific gravity of fully charged battery
442) what is meaning volt-hz ration,where is necessry tomaintain and why. specialy during increase the power of generator.
443) when we given 3 phase supply to ups system, but out put comes with 3 phase + neutral how it possible? pls explain.
444) How to select a D.G set for calculated load of 110kW..?
445) why fuse not recomended to neutral
446) How do you think they do earthing or grounding in ships and aeroplanes?
447) what is EIB lighting control system? what is the advantages of this system
448) how to check dc current,how to fix ammeter in dc line
449) HOW DO A DISTANCE RELAY SENSES THE FAULTY ZONE
450) why rotor current reading is taken & why not stator
451) What is difference between miniture circuit breaker and module case circuit breaker up to 63Amp
452) WHERE IS THE LIGHTING ARRESTER SHOULD BE PLACED IN DISTRIBUTION LINES
453) why rating of motor in HP
454) how electronic energy meter works
455) How we can determine short circuiting current any plant and for example a plant which power generation is 415 volts and plant load is 500 kw
456) if you short the any 2phase(R,Y,B),why fuse get blown
457) WHY WE CAN GENERATE POWER IN 3PHASE MODE ONLY NOT IN 4 OR 5 PHASE
458) How can the direction of a three phase induction motor be reserved
459) phase clearance between phase to phase and earth.
460) how to calculate cable size for the motor
461) what is F.A.P in fire alarming system
462) what is the function of fire alarm system
463) give types of Air conditioners commonly used &its use
464) block diagram of 2 ups system connected in hot stand by mode
465) what r the safety measures in UPS ? explain all
466) what is the dedicated neutral earth in ups?
467) give single line diagram of D.O.L and star -Delta starter
468) give single line diagram of D.G distribution form alternator to main L.T panel
469) if AVR fails in D.G set, what will be the effect
470) explain safety measures in alternator
471) what r the earthing required for commissioning of D.G set
472) what type of battery used for starting D.G?state its function
473) what is H.T?specify the range
474) what is W.T?specify the acceptable range
475) what is O.T?specify the acceptable range
476) what is S.T?specify the range
477) what is L.T?specify the range
478) i am going to correct power factor of 1600kw induction motor,when i calculate capacitance of capacitor it is three time more in star connection than delta. if motor is star connected which connection i shall adopt for capacitors and reason for adopt this connectio
479) how do you calculate IKW(consumption per TR) in HVAC
480) How can i modify the design of 3 phase induction motor to be as 3 phase synchronous motor?
481) According to general circuit diagram of 1-Phase t/f , why the primary is not get short circuited ,even though the supply terminals both are directly connected through primary winding
482) What will happen if supply to three phase motor is given wiyhout inerting rotor in it?How much current it will draw
483) How the neutral earthing is connected in DG alternator
484) Explain the working principle of Synchronous Generator and Assynchronous generator
485) why we use to transmit the power in three phases intead of single phase
486) what is efficient load of transformer in percentage
487) What is the Surge suppresor? Why using in a UDB's and How it work
488) How to select Main CB Rating for 187 KW Load
489) if we know Fault level say 25 KA , How to decide busbar size for Distribution network of 1000 Amp Breaker ? Sample Calculation or Farmula Available or not
490) what happen to the voltage and current in all phases when an earth fault occur in a phase in three phase three wire system(delta connected)..
491) why AC cannot to be stored and DC cannot be transmitted
492) why are use star delta startor
493) what is the reactance,capacitance & impedence electrical armoured & unarmored Cables
494) how to calculate the loss tangent of electrical cables
495) How to calculate the current carrying capacity of electrical cables
496) what happenes if two voltage source connected in parallel will be connected to load.
497) why the voltage level is changed when the unearth cable is earth
498) Why we are measured insulation resistance applied through DC Voltage?
499) what is the differnce between vector and phasor? are both same or there is difference between two term.
500) why odd hormonics only will effect the power system.why not even hormonics
501) what is the function of commutator in dc motor
502) how to calculate the no. of earth pits required for an electrical installation
503) what is the easiest method of short circuit current calculation
504) What is the difference between Isolator & Load Break Switch
505) Can any one explain me about 2 phase motors
506) how to calculate AH of a battery
507) If one 10 Hp 3phase induction motor connected in 380volt 50Hz. and again its connected to 380volt 60Hz. howmuch currrent and power take on both time
508) what is earthing.how we make it,describe briefly
509) why use generator Earthing/Graunding
510) What is the battery voltage limit
