7.30830.32.00
60
4.3)
Calculate setpoint reading
“I”
for current output:
I = I
0%
+
Y
X
(I
100%
- I
0%
) in mA
I
0%
current (0/4 mA) at 0% flow rate
I
100%
current (20 mA) at 100% flow rate
4.4)
Calculate setpoint reading
“f”
for pulse output:
f =
Y
X
* P
100%
in Hz
P
100%
pulses per second (Hz) at 100% flow rate
5)
Turn switch
D
(GS 8 A front panel) to “+” or “-“ (
f
orward/
r
everse flow).
6)
Set switch
Y
(GS 8 A front panel) to the value determined as described above.
7)
Check setpoint readings
I
and
f
, see items 4.3 and 4.4 above.
8)
Deviation < 1.5% of setpoint. If higher, replace signal converter, see Section 8.7.
9)
Linearity test: set lower Y values, readings will drop in proportion to the calculated values for Y.
10)
Switch off power supply
after completing the test.
11)
Disconnect the GS 8 A.
12)
Re-assemble in reverse order .
13)
The system is ready for operation after the power supply is switched on again.
Example
Full-scale range
Q
100%
= 113.1 m
3
/hr (Fct. 1.01)
Meter size
DN
= 200 mm = 8 inch (Fct. 3.02)
Current at Q
0%
I
0%
= 4 mA (Fct. 1.05)
Q
100%
I
100%
= 20 mA (Fct. 1.05)
Pulses at Q
100%
P
100%
= 280 pulses/hr (Fct. 1.06)
Primary head constant
GK
= 3.571 (see instrument nameplate)
Constant (
V
in
m
3
)
(
t
in
hr
)
K
= 7074 (see table)
(
DN
in
mm
)
Calculation of
“X”
and setting of
“Y”
:
X =
Q
100%
* K
GK * DN
2
=
113.1 * 7074
3.572*200*200
= 5.6
Y = 5
, setting of switch Y, see GS 8 A front panel
(comes closest to the value of X and is smaller than X).
Calculation of setpoint readings
I
and
f
I = I
0%
+
Y
X
(I
100%
- I
0%
) = 4 mA +
5
5.6
* (20 mA – 4 mA) = 18.3 mA
Deviations are permissible between 18.03 and 18.57 mA (equivalent to
±
1.5 %).
f =
Y
X
* P
100%
=
5
5.6
* pulses/hr = 250 pulses/hr
Deviations are permissible between 246.3 and 253.8 pulses/hr (equivalent to
±
1.5 %).
