DMR35-ACV Series

AC Voltmeter

DMR35-ACV.A01.D04 Page 8 of 11

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(CONTINUED):

RMS MEASUREMENT MODE VS. AVERAGE MEASUREMENT MODE.

In the case of a sinusoidal waveform, the figure below shows the relevant quantities.

Peak = 1.000

RMS ≈ 0.707

0

‘Average’ ≈ 0.637

The table below lists the crest factor, RMS and average values for various familiar waveforms. It illustrates the extent RMS-adjusted average

measurement can vary significantly in relation to the RMS measurement for signals with non-sinusoidal waveforms.

Waveform

Crest

Factor

RMS Value

‘Average’

Value

Average

Value with

RMS

adjustment

% Deviation

from RMS

Sinusoid

0

1

1.414

0.707

0.637

0.707

0%

Square wave

0

1

1.000

1.000

1.000

1.111

+11%

Triangle

0

1

1.732

0.577

0.500

0.555

-4%

Phase-

controlled

Sinusoid –

leading 50%

0

1

2.000

0.500

0.318

0.354

-29%

While an ideal measuring instrument would be able to handle any input waveform, realizable meters have restrictions on the maximum allowable

crest factor for accurate measurements. DMR35 AC meters are designed to handle signals with crest factors up to 3 with minimal additional

measurement errors.