Answer / raghavendran

Tan Delta test is performed on transformers to test the
insulation strength of its Bushings,Oil,Winding - winding
insulation Strength.It is also called as dielectric
Dissipation factor.it is measured by applying Voltage across
the Insulation and the intensity of the charging current say
(Ic) and resistive current (Ir).the value of Ir should be
low and thus denoting that the insulation is good.

Answer / praveen

Tan Delta, also called Loss Angle or Dissipation Factor testing, is a diagnostic method of testing cables to determine the quality of the cable insulation.In a perfect capacitor, the voltage and current are phase shifted 90 degrees and the current through the insulation is capacitive. If there are impurities in the insulation the resistance of the insulation decreases, resulting in an increase in resistive current through the insulation. It is no longer a perfect capacitor. The current and voltage will no longer be shifted 90 degrees. It will be something less than 90 degrees. The extent to which the phase shift is less than 90 degrees is indicative of the level of insulation contamination, hence quality/reliability. This “Loss Angle” is measured and analyzed.

Answer / vinod

same

why the starting voltage drop in a cable needs to be limited?what is percentage of the voltage drop allowed during starting?

0 Answers  

---

Why Auto Transformer is called "Auto"? What is the logic?

1 Answers  

---

what is the difference between induction and synchronous motor?explain in simple words?why 3 phase motor is given preference over single phase motor.

10 Answers  

---

Dear all, i completed M.E(Power Electronics & Drives) 2011 passed out having 78% so i need job in core side but i don't know how can i receive the calls from electrical companies and i uploaded my CV in naukri, times jobs etc.. In that iam not recieved any mails from good companies so give me best procedure plzzzzzzzzzzzzzzzzzzzzzzzz..... Thanks, K.Linga Reddy Email-id:-lingareddykmthm@gmail.com Ph no:-08015402078

0 Answers  

---

When and where resistance earthing is used ? How to calculate the time constant for earth fault

0 Answers  

---

what is the function of open delta System?

1 Answers  

---

what is model question rrb junior engineer electrical gr.II

0 Answers  

---

how we do Vector group ,magnetic balance and tap changer test in Transformer?

0 Answers   Afcons, BSL, HPL,

---

Isolation transformer primary to sec turns ratio?

2 Answers  

---

Is the installation of the filter cloths necessary before spreading the gravels at the transformer yards?

0 Answers  

---

How the oil level of the Buchholz Relay come down.

3 Answers  

---

if three phase supply is given to single phase transformer, what will happen?

3 Answers  

---