UEi Test Instruments DM397 - Manual (Page 13)

Continuity
Diode Test
Capacitance (5,000 counts only)
*1. Accuracy with film capacitor or better
*2. Using Relative (REL∆) mode
Frequency, Duty Cycle, Pulse Width and Temperature
dBm and 1mS PEAK Hold (5,000 counts only)
Burden Voltage (A, mA, µA)
G l o s s a ry of Te r m s
Average sensing RMS calibrated: RMS (Root-Mean-Square) is the
term used to describe the effective or equivalent DC value of an AC
signal. Most digital multimeters use average sensing RMS calibrated
technique to measure RMS values of AC signals. This technique is to
obtain the average value by rectifying and filtering the AC signal. The
average value is then scaled upward (that is, calibrated) to read the
RMS value of a sine wave. In measuring pure sinusoidal waveforms this
technique is fast, accurate and cost effective. However, in measuring
non-sinusoidal waveforms significant errors can be introduced because
of the different scaling factors involved with changing average to
RMS values.
True RMS: True RMS is a term which identifies a DMM that accurately
responds to the effective RMS value regardless of the waveform shapes
such as square, saw tooth, triangle, pulse trains, spikes and transient
glitches as well as distorted waveforms with the presence of harmonics.
Non-sinusoidal waveforms may cause:
• Overheating transformers, generators and motors to burn out
faster than normal
• Circuit breakers to trip prematurely
• Fuses to blow
• Neutrals to be overheated due to the triplen harmonics present
on the neutral
• Bus bars and electrical panels to vibrate
Crest Factor: Crest Factor is the ratio of the Crest (instantaneous peak)
value to the True RMS value, which is commonly used to define the
dynamic range of a True RMS DMM. 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 ty p i cally specified in terms of dB (decibel). This
meter has a NMRR specification of >60 dB at 50Hz / 60Hz, which provides
the 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. This meter has a CMRR specification of >60 dB at DC to
60 Hz in AC volts measurement function and >120 dB at DC, 50Hz and
60Hz in DC volts measurement function.
DM397-MAN P. 12
Audible threshold: The beeper sounds if the measured resistance is lower than 10 Ω,
and turns off when greater than about 70 Ω.
Response time: < 1 m sec.
Range Accuracy Test Current (typical) Open Circuit Voltage
4 V 2% + 1 1 mA <3.0 V DC
Range Resolution Accuracy * 1
5 nF 1 pF 1.0% + 5 * 2
50 nF 10 pF 1.0% + 3 * 2
500 nF 100 pF
5 µF 1 nF 2.0% + 3
50 µF 10 nF 3.0% + 3
500 µF 100 nF
5000 µF 1 µF 3.5% + 5
Function Range Resolution Accuracy
Frequency 50 Hz 0.001 Hz
[Minimum 500Hz 0.01 Hz
Frequency: 5 kHz 0.1 Hz 0.002% + 3
0.5 Hz 50 kHz 1 Hz
sensitivity 500 kHz 10 Hz
250 mV] 5 MHz 100 Hz
Duty Cycle 0.1% to 99.9% 0.1% 0.5 Hz to 300 kHz (pulse width > 3 µ sec.)
(0.1% + 0.05% per kHz+1 count) for 5 V
input (Logic signals only)
Pulse Width Input Frequency Pulse width > 3µs
0.5 Hz to 300 kHz
Temperature -58˚ to 2.372˚F 0.1˚F with k-type thermocouple
(-50˚ to 1.300˚C) (0.1˚C) ±5.4˚F (±3˚C) typical
Function Characteristics Accuracy
Selectable reference impedance of ±0.25 dB + 2 digits
dBm 1 to 1, 9 9 9 (@ 40 Hz to 20kHz)
At 600 : -11.76 dBm to 54.25 dBm
Input impedance: 10M, 30 pF nominal
1 mS PEAK Specified voltage or current measurement accuracy ±30 counts of the peak
value of a single 1 mS pulse.
Function Range Burden Voltage (typical)
500 µA 150 µV / µA
mA / µA 5000 µA 150 µV / µA
50 mA 3.3 mV / mA
500 mA 3.3 mV / mA
A 5 A 0.03 V / A
10 A 0.03 V / A