what is the difference between Central Battery System and UPS in applications and uses? and why UPS suitable for Computers and central battery for emergency lighting?

9700

What is the de rating factor of cable? What is the importance of the de rating factor in cable selection?

1623

What determines the thickness of the lamination or stamping?

1174

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.

1481

3phase motor can be used as a Prime mover for alternator.

1174

what is subtransient , transient and steady stateac components

1715

Dear all, how we select the cable size according  to current with or without including different correction factor , is there any direct method for sizing of cable... 

1706

what is control supply rating of a machine

1493

why there using acb enclosure in big buildings

1536

1.what is the difference between ct and cvt? 2.what is the difference between pt and cvt? 3.what is the difference between relays and circuit breakers?

2287

What is the comparison between 30mA DP RCCB and 100mA DP RCCB and can replace it against 63A MCB

1112

What is the difference between alternator and generator?

740

do any one help me to get "C" license,, i have doubts ,,, if mediators ter pls call me,, my no is 8056640042

1030

What is making & breaking current ???

973

how we sesign the transformer give some specifion regarding design of transformers

1470