Can you please explain what RMS value is?

Answer 1

RMS stands for Root Mean Square. It is a method of averaging where you take the squares of a bunch of samples, average them with an ordinary mean, and then take the square root. This gives greater weight to larger values. In the case of an ordinary sine wave, the RMS value is 0.707 times the peak value, 0.707 being 1/2 the square root of 2, and the peak value being one half the peak-to-peak value. For example, in the US, a "standard" 117VAC line voltage is actually an RMS voltage that corresponds to a peak voltage of 166VAC.

RMS is a necessary unit because, often, the waveform is not sinusoidal, it is sawtooth, such as in a power supply. Using an ordinary VOM, calibrated for a sinusoidal AC scale in such a case, will give an inaccurate reading of ripple voltage. Most modern DMM's have a true-RMS mode which will work correctly by using sampling and analysis technology.

RMS is also a necessary unit because RMS is a better indication of how much power a signal can impart to a load.

Another answer

RMS stands for Root Mean Square value.

In electrical technology, where alternating current (AC) is used, RMS Voltage and RMS Current (Amps) must be used to calculate the average power supplied or consumed. See the link below on how to find the RMS.

In fluid flow technology related to gases, velocity is calculated as an RMS value because it can be used to find the average velocity of an ideal gas.

Yet Another Answer

Because a AC current is continuously varying in both magnitude and direction, it's necessary to measure it in a meaningful way. The rms-value of an AC current is equivalent to the value of DC current necessary to do exactly the same amount of work. For example, a sinusoidal AC current which peaks at 100 A has an rms-value of 70.7 A, and does exactly the same amount of work as a DC current of 70.7 A.

Answer 2

RMS value is required only in case of alternating direction voltage or current.

So rms voltage/current is defined as the direct voltage/current which gives out same amount of heat energy in a given resistor in a given duration as the alternating voltage/current produces in the same resistor in the same duration.

The mathematical formula to find the rms value right from the peak value is:

Vrms=Vpeak/1.414

Answer 3

RMS is root mean square, it is defined as 1/sqrt(2) of the Peak - neutral voltage of a sine wave (no DC).

**************************************************************

The r.m.s. is the value of alternating voltage or current which gives the same heating effect as the same value of direct voltage or current.

Answer 4

rms voltage is a 'root mean square' voltage. This is used because every second amplitude of the voltage keeps varing between various peaks. Sometimes we also do refer to peak voltage also.

Answer 5

root mean square