metrix.Theoretical Introduction
MULTIMETERS
Multimeters
Choosing multimeter
■ Type
Choose the AVG type for measurements sinusoidal signals.fr
.
F C
RMS val. multimeter's bandwidth
indicates the instrument's ability process these signals.
• the weakest element that defines your level protection. counts
■ Bandwidth
This the frequency range within which the multimeter can measure
accurately.
■ Accuracy
This the difference between the signal's true value and the value displa
It may differ according the calibre and usually expressed follows:
E reading counts
■ Crest factor
This the ratio the peak (highest) value signal the RMS value.
Detailed product brochures can downloaded from www.
There direct relationship between the resolution, the calibre and the number
of display counts:
Resolution =
Calibre
No. Otherwise, opt for TRMS instrument, preferably
offering selection AC+DC coupling.
Thus, its mechanical protection, leakproofing, weight, handling and general ergonomics are crucial factors for the
instrument's reliability, life span and operational effectiveness.
■ Safety rules and good practice:
• Use measurement instruments and accessories which are suitable for the application and measurement conditions.
Initial signal
5 Hz
150 Hz
1
250 Hz
h 1
A t
.Any accessory with even slight defect must replaced immedia
tely longer guarantees your safety.
• Only use accessories perfect condition.), you will longer protected the event a
fault overvoltage. you replace them with more economical models, even
worse, pieces metal (copper wire, aluminium foil, etc. you use accessories with lower category or
voltage rating than your measuring instrument, reduces the overall safety level guaranteed your measuring
system. Peak value
L* Vy
■ Other important features
The instrument must suitable for its environment and operating constraints. crucial when the signal distorted because, according
to Fourier series development, periodic signal any shape can be
broken down into set elementary sinusoidal signals whose
frequencies are multiples the fundamental.
■ Number display points
This indicates the instrument's maximum display capacity.
• High-rupture-capacity fuses are safety elements. It
helps estimate the rate distortion which the multimeter can measure
correctly. f
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