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INSTRUMENT
AMP. SAC100
/ SAC420
(HIGH
ACCURACY MILLIVOLT AMPLIFIERS)
SAC100 and SAC420 are high accuracy
amplifiers that are specially designed for use with thermopile sensors. The
primary application is with heat flux sensors, pyranometers, net-radiometers and
pyrheliometers.
The specifications of both amplifiers are such that they
can be used with the highest class of this type of instruments, while ensuring
that no accuracy is lost. Also the amplifiers contain protection against
transients (useful in meteorological applications). In this sense, SAC100 and
SAC420 are unique. SAC100 has a voltage output, SAC420 has a 4 to 20 mA current
output.
While the current output in some applications has the
advantage of extra quality assurance for cable breaks (current will go to zero),
it has the disadvantage that it cannot be used with input signals that can go
both positive and negative, such as net-radiometers and heat flux sensors in
meteorological situations.
SAC 100 & SAC 420 FEATURES & BENEFITS
-
Extremely low zero offset and range drift over the entire
temperature range.
-
Adaptable sensitivity, by do-it-yourself mounting of
ordinary metal film resistors
-
Possibility of feeding through extra wires, e.g. from
temperature sensors or more voltage signals that are led through the same cable
as the signal that must be amplified.
-
Can be used with the highest accuracy lowest signal
sensors without loss of accuracy.
-
Suitable for outdoor installation.
SPECIFICATIONS
|
|
SAC100 |
SAC420 |
|
Typical
sensors |
Heat flux
plates
Pyranometers
Net –radiometers
Pyrgeometers
Pyrheliometers
Albedometers
Connectors for wiring of additional temperature
sensors are available inside SAC 100 housing |
Pyranometers
Pyrheliometers
Albedometers
Heat flux plates in applications with only one-way
heat flux
Connectors for wiring of additional temperature
sensors are available inside SAC 420 housing |
|
Minimal full scale
input |
+/- 3
mV |
+ 3
mV |
|
Maximum full scale
input |
1000
mV |
1200
mV |
|
Output |
Voltage between +3
and –3 Volt |
4 –20 mA current
loop (to 3.5 mA) |
|
Standard Amplification
(A) |
200 |
1
mA/mV |
|
Do-it –yourself
adjustment of A by resistor R |
A =
(2*(50.000/R)+1
A from 1 to 1000. R can be composed of 1 to 3
separate resistors in series. |
10 mV full scale,
using 4 to 14 mA range
R = 100* full scale input
A from 16 mA/5 mV to 16 mA/1200 mV. R can be
composed of 1 to 3 separate resistors in series. |
|
Example of R
calculation |
R of 1000 ohm plus
10 ohm gives an A of 100. |
Heat flux sensor
UT 03 delivers 4.56 mV an 1000 W/m2 heat flux. R of 456 ohms delivers 4 mA at
zero input and 14 mA at 1000 W/m2. AC 420 is only to be used if the
heat flow does not reverse / change sign. |
|
Specifications of
R |
1%, 50 ppm metal
film resistor |
1%, 50 ppm metal
film resistor |
|
Input
impedance |
1 Mohm |
1
Mohm |
|
Ambient
temperature range |
-20 to + 50 °
C |
-20 to + 50 °
C |
|
Temperature range
for storage |
-30 to + 70 °
C |
-30 to + 70 °
C |
|
Zero drift at
output |
< 0.05 mV/°
C |
< 0.25 m A/°
C |
|
Range drift at
output |
< 20 ppm/°
C |
< 20 ppm/°
C |
|
Initial
accuracy |
0.1% |
0.1% |
|
Power
supply |
8 – 24
VDC |
10 – 24
VDC |
|
Supply
current |
< 20
mA |
n.a. |
|
Loop voltage to
output ratio |
n.a. |
< 10 m A /
V |
|
Output
impedance |
< 10
ohm |
n.a. |
|
Maximum
load |
< 1
mA |
n.a. |
|
Response
time |
< 1
s |
< 1
s |
|
Dimensions |
120 * 120 * 80
mm |
120 * 120 * 80
mm |
|
Connection |
Swivels for cables
from 4 to 6 mm diameter |
Swivels for cables
from 4 to 6 mm diameter |
|
Input
protection |
Protected against
static discharge, reverse power |
Protected against
static discharge, reverse power |
|
Options |
MA 220 mains
adapter for 220 VAC. |
MA 220 mains
adapter for 220 VAC. |
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