Direct Current Measurement - Gossen MetraWatt METRAHIT ENERGY TRMS System Multimeter Operating Instructions Manual

5.8.1 Direct Current Measurement

Measurement of Pulsating, Direct and Alternating Current, and Frequency
A (DC+AC), A DC and A AC/Hz Direct, and Total Harmonic Distortion
Ð First disconnect supply power from the measuring circuit or
the power consumer (1), and discharge any capacitors. See
circuit diagram on next page.
Ð In accordance with the current to be measured, set the rotary
switch to A or A /~.
Note
Set the CL iP parameter to 0FF in the current clamp setup
menu. Otherwise all displayed measured values are cor-
rected by the amount resulting from the selected transfor-
mation ratio for an interconnected current clamp trans-
former. The clamp symbol is also displayed. Refer to section
5.8.2, "Current Measurement with Current Clamp Sensor";
regarding adjustment.
Ð Select the type of current appropriate for the measured quan-
tity by briefly pressing the FUNC | ENTER multifunction key. Each
time the key is pressed, the instrument is switched back and
forth between A (DC + AC)
thd, which is indicated by means of an acoustic signal. The
current type is indicated at the LCD by means of the
(DC+AC) , DC or AC
TRMS TRMS
thd measurement: Total harmonic distortion appears at the
main display as a percentage relative to the fundamental har-
monic, and the total RMS value of distortion appears at the
right-hand auxiliary display in A.
Ð Safely connect the measuring instrument (without contact re-
sistance) in series to the power consumer (2) as shown.
GMC-I Messtechnik GmbH
Measurements: V/Hz/dB – PQ/
, A DC, A AC /Hz and %
TRMS TRMS
symbol.
– MHz/% – /nS/R
– /
SL
Ð Switch supply power to the measuring circuit back on (3).
Ð Read the display. Make a note of the measured value if the in-
strument is not being operated in the memory mode or the
transmission mode.
Ð Disconnect supply power from the measuring circuit or the
power consumer (1) once again, and discharge any capaci-
tors.
Ð Remove the test probes from the measuring point and return
the measuring circuit to its normal condition.
Crest Factor Display
Crest factor is displayed for current in the A (AC+DC) function
simultaneously along with the measured current value. The peak
current value is measured simultaneously in a separate measuring
circuit to this end, and crest factor is displayed within a range of
1.0 to 11.0.
This value indicates the quality of the applied signal. The only pre-
requisite is a periodic signal with a valid frequency (see table).

Measuring range: 1.0 CF
Typical (not specified) maximum deviation for signals greater than
5% of the measuring range:
CF  3.0
Frequency
02
10 to 70 Hz
02
70 to 440 Hz
05
440 Hz to 1 kHz
> 1 kHz: Not valid
– Temp – /m – W/Wh – A/Hz/thd

11.0; resolution: 0.1
3.0 < CF  5.0 5.0 < CF  10.0
0.2
0.5
Not valid
Not valid Not valid
Not valid Not valid
0.5
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