Sir we have 12.5 MVA(110/11KV) transformer (Y-Y) connected,which tripped showing earth fault,when we charged transformer it stood OK ,but on connecting 11 KV feeders it tripped showing earth fault.our service engineers found that the B phase and R phase phase connecting to neutral broken from HV OLTC(on load tap changer),and R phase and Neutral is ok.Dissolved gas analysis shows that accetline content is high,tan delta value is 12.My dout is it is an internal fault of transformer,why REF or diffrential relay is not acted?

1 Answers  

---

what is the slip of synchronous motor

1 Answers  

---

how many earthing should need for UPS, where its connected

7 Answers   HCL,

---

if a 3phase 100kva distribution transformer , 400 v,50 hz, 4-wire system is loaded at 160 k.w mostly 1-phase Lighting & Airconditioning split a.c load what will be the net effect on the power system in terms of voltage, powerfactor, current , efficiency of xformer

0 Answers  

---

Hi all, please could anybody give me a suggestion about Electrical designs and calculations .. what text book should i follow as i am a trainee engineer and here work going not so favorable to me so please help me friends .. A small discription about my work which is going here is all about Electrical designs like cable sizing, lighting, lightning, Gensets sizing, motor sizing, transformer sizing, generator sizing, circuit breakers, PDB MCC PCC SLDB MLDB panels, Single line diagrams mainly, substation desings, cable routing and layouts, reactive power compensations, power factor improvement, voltage drop calculations, power generations, power transmission, power distributions all calculations i need .. please please if anybody experienced with this problem and got a solution then please help me .. just i need an apt text book for these all calculations and designs ..

0 Answers  

---

1)What is a Triode? What are its uses? 2) What is a Triac? 3) What is a Thyristor?

0 Answers   Bosch,

---

whether energy meter is connected in series or parallel.why?

2 Answers   Encom,

---

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

0 Answers  

---

which is better to use svc or synchronous condenser why ?

0 Answers  

---

How can I communicate with an Areva MiCOM P121 relay by RS485 port? In other word, which command can I send and what information can I have recieved? please send some refrences, please. thanks

3 Answers  

---

As per the Anchor capstan motor specification, full load current is 200A. starting current is 1750 A and acceleration time is less than 8 seconds. Please guide for selection of cable size.

0 Answers  

---

Is the force acting between two parallel conductors of infinte length carrying AC of frequency 50Hz remians constant with respect of time? If not then what would be the frequency of the force acting?

1 Answers  

---