Casella CEL CEL-160 - Manual (Page 9)

AC OUTPUT: This provides the conditioned AC
signal at a level of 1.4 V RMS via 3.3 kW, for
FSD.
DC INPUT: DC inputs will be accepted by the
socket at a nominal sensitivity of 140 mV/dB
when the DC gain control (GAIN-CAL) is in the
'CAL' position. It must be noted that the
instrument assumes that the DC input signal is
in the log DC form and produces amplitude
annotations accordingly.
REMOTE: All the necessary control signals for
peripheral instrumentation are available from
this socket. Full details are given in Figure 2.
POWER: Both constant voltage and constant
current supplies provided by the CEL-3732 AC
Adaptor and NiCad Battery Charger are
connected to the Graphic Recorder via this
socket. Reference should be made to Section
2.2.2 and the CEL-3732 Operating Instructions.
CEL-160 Socket Connections
8-pin DIN Preamplifier
Pin No.
Function
1 150 V polarising voltage.
2 Signal from preamplifier. Input impedance 20 kW.
Maximum input ±8 V peak to peak.
Maximum DC offset 15 V.
3 -5V nominal, supply to preamplifier.
Maximum current 5mA.
4 0 V.
5 30 dB gain signal. Goes from -8 V to +8 V
when gain selected. Selected on bottom five
ranges.
6 +5 V nominal supply to preamplifier.
Maximum current 5 mA.
7 AC input. Impedance 240 k Ω .
Maximum input ±80 V peak to peak.
Maximum DC offset +15 V.
Attenuated 20 dB re. Pin 2.
8 Spare. (+18 V10 mA Accelerometer bias
option).
8-Pin Remote
Pin No.
Function
1 Input 1, normally 0 V.
2 Input 2, normally +5 V.
Control inputs presently used in filter programs
to sense state of filter.
3 Step filter, 5 to10 µ S pulse to +8 V with 10 k Ω
source impedance.
4 Reset filter, normally +8 V (via l0 k Ω ). Shorted
to 0 V for 5 - 10 µ S for reset.
5 Input 3, normally 0 V. Only available on Level
1 recorders. No present usage but available
for special software.
6 0 V.
7 +8 V output for special cables/interfaces.
Maximum current 10 mA.
8 Spare.
Figure 2: Pin functions
3.3 Scale Annotations
The CEL-160 records over a 50 mm span to a
resolution of 1% and accepts 25 m rolls of
electrosensitive paper. Both X and Y grids and
annotations are generated by the recorder and
are printed at the same time as the recorded
trace.
3.3.1 Amplitude Axis (Y)
Two kinds of amplitude scaling are provided by
the instrument. Firstly, an amplitude grid and
secondly amplitude annotation.
The amplitude grid is produced by
repeatedly firing every fifth pin in the writing
comb at half intensity. This produces 20
amplitude bands across the scale, the actual
value of which depends upon the measure-
ment configuration. For example, with log
RMS recording they would represent either
0.5, 1 or 2.5 dB divisions depending on
whether the dynamic range switch was in the
10, 20 or 50 dB positions. In the linear mode
they divide the chart into 5% bands and in the
AC mode between ± 100% in 10% steps. In
the AC waveform mode the amplitude grid is
reversed out when the recorder is producing
deflections crossing the grid position. This
produces the effect of a white grid line against
the black traces.
The scale annotations produced by the
instrument depend upon the mode of
operation and in all cases follow the first time
marker after a full time print. In the RMS log
and DC modes annotations of FSD and MSD
are produced as defined by the settings of the
dynamic range and range (dB) step attenuator
switches. In the RMS linear mode the
annotation is always 0-100 to represent
percentage scale deflections and it is
independent of the gain settings. In the AC
waveform mode the signal is balanced about
the centre line of the paper and no scale
annotations are provided. When in the real
time analyser mode each individual third
octave band is annotated with the band level in
alphanumeric form.
3.3.2 Time Axis (X)
The traditional method of recording time on
recorders is to relate the length of paper
consumed to the start time via the paper
speed. These arrangements can be extremely
inaccurate especially over long periods and
there is no method of recording absolute time.
The CEL-160 does not use distance as the
method of calculating elapsed time but records
real or elapsed time directly on to the chart. It
CEL-160 Graphic Recorder - Page 9