rajendra


{ City }
< Country > india
* Profession *
User No # 102442
Total Questions Posted # 11
Total Answers Posted # 12

Total Answers Posted for My Questions # 6
Total Views for My Questions # 44334

Users Marked my Answers as Correct # 47
Users Marked my Answers as Wrong # 4
Questions / { rajendra }
Questions Answers Category Views Company eMail

how to interlock 2 incomer,1 buscoupler MCCB,like we interlock an ACB... pls answer this question and if possible send me the ckt diagram..

 2 Electrical Engineering 14786

How to calculate incomer of a capacitor bank/feeder from its KVAR, AND how to calculate the copper busbar for rated incomer,like for 400A we calculate the 40x10 of aluminum busbar.

 1 Electrical Engineering 6740

i seen a 132kv/11kv transformer,and thier is a sugar factorys 10MW EXPORT PLANT,MY QUESTION IS THAT WHEN THEY EXPORT ELECTRICITY THEY USE THE SAME TRANSFORMER AND THE CONNECT IT TO 132/11KV TRANSFORMERS SECONDARY SIDE CAN ANY ONE EXPLAIN IT.. THE TRANSFORMER IS OF KIRLOSKAR MAKE AND IT HAS TAP CHANGER.

 1 Electrical Engineering 2590

As we use capacitior bank in 3ph ckt for improvement of PF, why not we use capacitor in single phase domestric use, at our house their are many inductive equipments,like fan,mixer,tube choke,air conditioner they also draw PF... by using capacitor can they improve PF. if yes--what are advantage and how to connect a capactor in single ph,and which type of capacitor if no- what are disadvantages.

 Electrical Engineering 1384

HOW TO CALCULATE S/C,O/C,E/F OF ACB.

Electrical Engineering 2140

what is earth fault relay 64T, why it is used in main Incomer and neutral CT of Transformer.

 Electrical Engineering 2956

what is the purpose of taking HV test in LT panel.

PCE,

1 Electrical Engineering 6301

In EDO ACBs what is a purpose of closing coil and motor, what is the operation of these devices are they inetconnected. means if we give supply to motor and by BCS we charge Closing coil,what exact is operation is and how it charge a spring of ACB. Sir if anybody has an wiring diagram please send me the link to operate and EDO breaker.

PCE,

Electrical Engineering 1621

We use MCCB not MCB for motor starters because MCCBs has capablity to drawout the motor starting current which is 5-6 times the full load current of motor for 1sec. Then why we use SDF in starter panel means MCC panels. Pls reply if any one knows this answer.

 1 Electrical Engineering 1952

what precautions to be taken while desigining a LT,HT panel. Eg-LT panel PCC panel with ACB installed. HT panel VCB panel with VCB installed. & what is main diffrence betwn IP54 & IP55 construction of panel.

Bhel,

Electrical Engineering 2482

How can we deside Short Ckt level of electrical System,Breakers etc.please provide formula to find SC of HV side & LV side

 Electrical Engineering 1382



Answers / { rajendra }

Question { 9369 }

What is the fuction of UV & how it works in circut breakers?
is it one type of relay?


Answer

UV IS Under voltage realease type relay,
uv is installed in breaker and it is designed so that when
the supply of its coil is interupted it opens the breaker.
when you give supply then only you can close the breaker.
it is installed manily for interlocking.
we can use them in almost all type of onload ckt breaker
like-- MCCB,ACB,VCB,SF6 Etc...


if their is any mistake in this answer pls post it,i am diploma holder and working in panel manufacturing co--
Rajendra sawant, miraj...maharashtra.

Is This Answer Correct ?    3 Yes 0 No

Question { 6586 }

why we somewhere use ryb
phase sequance, somewhere
use uvw, and somewhere abc??


Answer

RYB colors are used for phase indication
UVW are used in motor terminal connection.

By-Rajendra.V.Sawant
Miraj.

Is This Answer Correct ?    0 Yes 0 No


Question { 3276 }

Can anyone explain about Control and power circuits of star delta starter & DOL starter ? How it works? please!


Answer

DOL- DIRECT ONLINE STARTER
we use one contactor,one thermal o/l relay
in this connection we use the contactors NO contact parallel to contactor coil after stop push button,
when we push start P/B and realease it at this time the NO
contact becames NC and the contactor run continously.

Is This Answer Correct ?    0 Yes 0 No

Question { 3373 }

What is switch disconnector fuse?


Answer

It Has HRC fuses which has 100kA breaking capacity.
SDF-switch disconnector fuse
SFU-switch fuse unit which are one & same.

By-Rajendra.V.Sawant.
Miraj.

Is This Answer Correct ?    3 Yes 0 No

Question { 3855 }

what is motor contrl center .


Answer

Motor Control Center is a Panel board which has all types of motor starters like.
1.DOL
2.Star/Delta
3.F/R starter.
4.VFD(up to 37kw)

It has an arrangment of all above starters with one main incomer.

Rajendra sawant
miraj.

Is This Answer Correct ?    4 Yes 0 No

Question { Apollo, 6808 }

how do you select the ct/pt rating in substation


Answer

First we should know the operational voltage of Substation,
transformer rating in MVA/KVA,Depending on this values we have to find the current,after getting all this values we can select the CT/PT ratings.


Rajendra Sawant
Miraj.

Is This Answer Correct ?    8 Yes 3 No

Question { 7800 }

Capacitor panel CT is normally fixed on Y phase of the main
panel.why???


Answer

no my friend,it depends on APFC relay,
1.in L&T make APFC relay ct is looped in R-phase.
2.in Sentron make APFC relay ct is looped in Y-phase.
3.in Sycon make APFC relay ct is looped in B-phase.

if you have any dout see all above relays wiring diagram.
For measuring PF APFC relay required any two phases & one CT sence on remaining phase from main PCC Phase.
Eg.(R-Y phase & BCT from Main Panel)

From--Rajendra Sawant
Miraj.

Is This Answer Correct ?    9 Yes 0 No

Question { 7800 }

Capacitor panel CT is normally fixed on Y phase of the main
panel.why???


Answer

Thanks Zia Mam,For Sharing Additional information,but what about the manufacturing relay companys who manufacture the relay which has R,Y,B phase Selection of CT which i have mentioned in above answer,should we select our relay as per our Phase Load.

From-Rajendra Sawant

Is This Answer Correct ?    0 Yes 1 No

Question { 2965 }

what is the step by step formula for calculating bus bar
phase and neutral size of a panel board.suppose the incomer
of panel board is 100A..???step by step answer please


Answer

It depend on which metal you are using copper/aluminum.
& it also depends on density.
to calculate busbars multipy cross sections.
For AL if density is 0.7/1A
Eg.for 100A incomer density .7 busbar is 20x10MM=140A.
with 1A density 10x10mm=100A
For CU standard density is 1.5/1.8A

From Rajendra Sawant
Miraj

Is This Answer Correct ?    3 Yes 0 No

Question { Hosco, 7614 }

what is the different ratings of ACB/VCB/SF6 which is used
at HT side


Answer

FIRST OF ALL CORRECT YOUR QUESTION,
ACBs are not Used In HT Side.
& THE DIFFRENT RATINGS OF VCB/SF6 Breakers Depends on your system voltage.
VCB ratings 11kv,33kv
SF6 available from 11kv to 440kv and so on.

from-Rajendra Sawant
Miraj.

Is This Answer Correct ?    11 Yes 0 No

Question { 3107 }

What are various modes for Mechanical interlocking of
breakers (for both MCCBs & ACBs)


Answer

For MCCB-Panel Door Lock is used with exteneded rotary handel.
& Pedal lock arrangement is also available in ROH.


For ACB-Castle lock or Racking Interlock is available.

Is This Answer Correct ?    0 Yes 0 No

Question { 2848 }

How i can select current transformer and meters for the
upgrading the panal..for 200kw to 600kw....i need to select
monitoring and protection ct,s and apmpire meter ,kw meter too.


Answer

First find the Full load current of 600KW Load & select Incomer of about 20% higher than FLC,consider the CTs rating as per the incomer rating.

Is This Answer Correct ?    6 Yes 0 No