Minipa ET-2907, Инструкция по эксплуатации, Страница: 59 / 98

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A pure sinusoidal waveform has a Crest Factor of 1.414. A badly distorted
sinusoidal waveform normally has a much higher Crest Factor.
NMRR (Normal Mode Rejection Ratio)
NMRR is the DMM’s ability to reject unwanted AC noise effect which
can cause inaccurate DC measurements. NMRR is typically specified
in terms of dB (decibel). The Meter has a NMRR specification of >
60dB at 50Hz/60Hz, which means a good ability to reject the effect of
AC noise in DC measurements.
CMRR (Common Mode Rejection Ratio)
Common mode voltage is voltage existing on both the COM and Voltage
input terminals of a DMM, with respect to ground. CMRR is a DMM’s
ability to reject common mode voltage effect which can cause digit
rattle or offset in voltage measurements. The Meter has a CMRR
specification of > 60dB at DC to 60 Hz in AC volts measurement function
and > 120 dB at DC, 50Hz and 60Hz in DC volts measurement function.
Burden Voltage
Burden voltage is a voltage drop across the input terminals of a current-
measuring device, caused by internal shunt resistance. Burden voltage
contributes measurement error, and should be as low as practical.
Temperature Coefficient
Temperature Coefficient is a factor used to calculate the change in
indication or output of an instrument with changes in temperature.
Uncompensated changes in temperature contribute uncertainty by an
amount determined by the temperature coefficient to instrument.