Instruction Manual VGC301 Controller
InstruTech, Inc.
Page 34
Coefficients for
voltage segment range of
7.6465 to 7.9102 volts
K
0
K
0
= +1.06
K
1
K
1
= -1.03
K
2
K
2
= +4.196562E-01
K
3
K
3
= -3.880208E-05
Coefficients for
voltage segment range of
7.9102 to 9 volts
K
0
K
0
= -2.05
K
1
K
1
= +1.02
K
2
K
2
= -5.106048E-02
K
3
K
3
= +4.554342E-06
Example: Measured analog output voltage is: V
1
= 5.6243 V.
Since analog output in this example is 5.6243 V, use the Coefficients from the fourth table shown in the previous page:
K
0
= -3.01, K
1
= +5.495931E-02, K
2
= -2.652588E-05, K
3
= +4.526774E-09
Use equation from the previous page; P = K
0
+ K
1
(454.67*V
1
)+ K
2
(454.67*V
1
)
2
+ K
3
(454.67*V
1
)
3
P = Pressure = 5.00 Torr
The following pressure vs. voltage table is derived from equations and coefficients listed above.
NONLIN 9V, Non-Linear Output Voltage vs. Pressure in Torr units for N
2
/Air
Pressure
(Torr)
Voltage
(Vdc)
Pressure
(Torr)
Voltage
(Vdc)
Pressure
(Torr)
Voltage
(Vdc)
0.0000
0.0000
2.0E-01
1.3310
4.0E+02
8.2587
1.0E-04
0.0016
5.0E-01
2.2289
5.0E+02
8.4375
2.0E-04
0.0031
1.0E+00
3.1352
6.0E+02
8.5915
5.0E-04
0.0077
2.0E+00
4.1968
7.0E+02
8.7196
1.0E-03
0.0153
5.0E+00
5.6243
7.6E+02
8.7862
2.0E-03
0.0302
1.0E+01
6.5245
8.0E+02
8.8271
5.0E-03
0.0727
2.0E+01
7.1531
9.0E+02
8.9193
1.0E-02
0.1385
5.0E+01
7.6145
1.0E+03
9.0000
2.0E-02
0.2536
1.0E+02
7.7804
5.0E-02
0.5260
2.0E+02
7.9102
1.0E-01
0.8583
3.0E+02
8.0743
An analog output of 10 volts indicates a faulty convection gauge or unplugged gauge cable.
