Arbiter Systems 931A, Руководство по эксплуатации

Страница: 74 / 161

harmonics, and also displays dashes with insufficient signal levels. Narrow-
band apparent power is determined by multiplying the fundamental
voltage by the fundamental current as seen in 3.9. Power Factor is the
cosine of the angle between
V
f und
and I
f und
as seen in 3.10.
Narrow-Band:
(3.9) V A = V
f und
×
I
f und
(3.10) P F = Cos ( θ )
3.6.4 Waveform Display
Press the WAVEFORM key at any time to display waveforms for the
signals at measurement channels 1 and 2. Initially, waveforms for both
channels will be displayed.
Display individual channels by pressing
CHANNEL 1 SELECT or CHANNEL 2 SELECT. Press the WAVEFORM
key again to display both wave shapes simultaneously.
The Model 931A Waveform Display includes a text display showing
the rms magnitudes for the two signals and the frequency of the signal at
Channel 1. The following example shows a typical Waveform Display:
Signals are aligned so that the zero crossings of each channel appear at
the left-hand edge of the display.
3.7 Timer Measurements
The Model 931A includes a timer for measuring events such as relay
contact timing. The timer has two channels, which are optically isolated
from the instrument common and from each other. Both inputs can accept
various triggering inputs, including:
ˆ
Contact opening or closure,
ˆ
AC applied or removed (20 - 300 Vrms),
ˆ
DC applied or removed (4 - 300 Vdc).
See Section 3.7.2.4, “Select Timer Trigger A” for more information.
58