Siemens PGC 302 Edition II - Electronics for FID and FPD

Electronics for FID and FPD
The FID signal is applied directly to a precision
analog-to-digital converter for extremely small cur-
rents in the pA range.
Operating voltage
The operating voltage is 300 V for the FID and 600 V
for the photomultiplier of the FPD. The voltage is
generated on the detector module from +24 V and is
electrically isolated.
Ignition
The ignition command resulting from an operator input
or a time program is converted in the detector module
into five 24-V pulses. These are converted in the igni-
tion module into high-voltage sparks.
Range
Each range has a dynamic response of 10
6
. Nine ranges
can be selected for the FID. The ranges result in an
attenuation from 2
0
to 2
8
. The table lists the maximum
detector current in each range.
Zero adjustment
The microcontroller on the detector module adjusts the
zero using software functions if an autozero is triggered
manually or by a time program.
Connection of detector
Refer to the connection diagram below.
Range Detector signal => Full-scale
at recorder range
0
0
1
2
3
4
5
6
7
8
0 ... 0,8 pA
0 ... 13 nA
0 ... 26 nA
0 ... 52 nA
0 ... 104 nA
0 ... 208 nA
0 ... 416 nA
0 ... 832 nA
0 ... 1,664
µ
A
0 ... 3,328
µ
A
0
14
15
16
17
18
19
20
21
22
X8
RUN
1
X8
X201
X202
Detector A
X 202
X 201
Detector B
X 202
X 201
A
D
Input signal
GND
20 bits
operating voltage
+300 V
U
U
Mm
+24 V
GND
Mm
1
2
3
4
5
6
7
8
9
10
FID am
p
lifier
X8
green: operating voltage
+ 300V
X3
Coax
I
g
nition
module
FID
brown: GND 24 V
white: ignition pulses
Detector electronics
9DETEKT.CHP, Stand Dezember 22, 1999
5