why high speed tripping relay is used in protection circuit why not normal relay

0 Answers  

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Why does not AC excitation use in rotor of AC Generator instead of DC excitation?

2 Answers   A2Z Group,

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What is the Difference between Ac Drives and Dc Drives? According to application, speed, Torque, cost, Reliability, Construction, Motor etc... Thankyou !!!

0 Answers   IFFCO, IIT,

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why we choose 50 or 60 hertz not other value for the power system?

4 Answers  

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Difference between transition and diffusion capacitance

0 Answers  

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STATE WORKING OF SF6 C.B.?

1 Answers  

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what is the back ground of transformer working? applying voltage to primary and emf inducing in primary and secondary? how it is possible? please answer me with scientific approach?

5 Answers  

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delta motor winding resistance I take normally single winding is 2.5, which value is came delta connection ie RY ?

0 Answers  

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In a single how much maximum current and watts using

0 Answers  

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how do we select a copper power cable for a 10 HP, 1440 rpm, 440V, 3 phase AC motor?

4 Answers   Rolling Mill,

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What is the difference between AC Drives and DC Drives?

14 Answers   College School Exams Tests, La-Gajjar Machineries, LG, Schneider, SMEL,

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1. A 380 / 220 V r.m.s. 3-phase 4-wire circuit carries loads of 8 + j8.1 ohm; 4 + j4.1 ohm; and 2 +j2.1 ohmin the three phases respectively. The length of the circuit is 100 m, and the resistivity of the phase conductors is 0.0005 Ω/m. The neutral conductor is of the same size as the phase conductors. a) Select a reference angle 0for the first phase. Then write down the three phase voltages in both polar format and complex number format. b) Make appropriate assumptions, and take temperature effects on resistance is insignificant. Calculate the currents in the three phases. (Note: Determine conductor resistance, and apply Kirchhoff’s Voltage Law) Based on the result, suggest a main switch rating for the circuit. c) Show your preferred direction of neutral current in a diagram, and then determine its value. (Note: Apply superposition principle, and Kirchhoff’s Current Law) Use its magnitude to show that in this circuit, the unbalanced load may increase the voltage drop in some of the phases. (Note: Also observe the common volt drip in neutral) State your assumptions, if there are any. d) Suddenly the neutral wire of the circuit is broken. Estimate the new currents in the first phase, i.e. Phase L1. State your assumptions, if there are any.

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