Explain the reason root mean square is used when measuring the voltage of an AC

Question

Explain the reason root mean square is used when measuring the voltage of an AC source. Calculate the voltage value of a sine wave at 135 degree whose VRMS=1000 VAC Show all work Define power factor and write the equation to calculate it explain why three-phase system are preferred over single-phase systems for power generation Explain the difference between wye and delta systems Given an example of when each would be used Calculate the reactive power in a balanced three-phase circuit when voltage of the load is 480 VAC, current of the load is 10 Amps, and the power factor is.9

Explanation / Answer

1) the root mean square value of a sine wave is a measure of the heating effect of the wave. when a resisstor is connected across a dc voltage source. a certain amount of heat is produced in the resistor in a given time. a similar resistor is connected across an ac voltage ssource for the same time. the value of the ac voltage is adjusted such that the same amount of heat is produced in the resistor as in the case of the dc source.this value is called the rms value.

3) the power factor is useful in determining useful power transferred to a load.the highest power factor is 1, which indicates that the current to a load is in phase with the voltage across it.when the power factor is 0,the current to a load is 90 degrees out of phase with the voltage.

the average power depends on the value of cosq, this is called the power factor of the circuit.

power factor(pf)=cosq=Pav/(Veff*Ieff).

4) A) THE POWER IN A SINGLE PHASE CIRCUIT IS PULSATING. WHEN THE POWER FACTOR OF THE CIRCUIT IS UNITY, THE POWER BECOMES ZERO 100 TIMESS IN A SECOND IN A 50HZ SSUPPLY.

B) TO TRANSMIT A GIVEN AMOUNT OF POWER OVER A GIVEN LENGTH, A THREE-PHASE TRANSMISSION CIRCUIT REQUIRES LESS CONDUCTOR MATERIAL THAN A SINGLE PHASE CIRCUIT.

C) IN A GIVEN FRAME SIZE, A THREE PHASE MOTOR OR A THREE PHASE GENERATOR PRODUCES MORE OUTPUT THAN ITS SINGLE PHASE COUNTER PART.

6) GIVEN V=480 VOLTS

I=10 AMPS

POWER FACTOR=0.9

Q=1.93*480*10*SIN(INVERSE COSINE OF 0.9)

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