YOKOGAWA RC400G, Руководство пользователя

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<6. Converter Operating Functions>
6-2
IM 12F4A1-01E
Figure 6.1 shows the discriminating method between the state either sample is present or not in
the measuring tank.
When a measured value of residual chlorine concentration decrease below the predetermined
value (set using function code “c” in <PROGRAM.1> mode), the applied voltage changes for a
very short time as shown in Figure 6.1. The diffusion current value change owing to this detecting
voltage is checked.
When sample is not present in the measuring tank, the diffusion current does not change. When
sample is present in the measuring tank and the state between the electrodes is not open, the
diffusion current changes presenting plateau characteristics.
F6.1.ai
Is
Is
A
A
Indicator
electrode
Counter
electrode
Indicator
electrode
Counter
electrode
A: Amplifier
Is: Diffusion current
V: Applied voltage
V
(a) When sample is present in the measuring tank
A: Amplifier
Is: Diffusion current
V: Applied voltage
V
(b) When sample is not present in the measuring tank
Is
Ip
0
V
Detecting
voltage
Setting
voltage
(Example: -0.40 V)
0
Time
Time
Time
Time
Is
V
Detecting
voltage
Setting
voltage
0
0
Figure 6.1 Principle of Detecting Out-of -Sample in Measuring Tank
The detecting voltage is applied periodically (approx. 10 min cycle) when the measured
concentration value decreases below the predetermined value (set using function code “c”
in <PROGRAM.1> mode) in <MEAS.> mode. As shown in Figure 6.2, the reverse voltage is
applied after the detecting voltage is applied so that the diffusion current changing time becomes
minimum. The detecting operation time in which the detecting and reverse voltages are applied is
a few seconds. Including this detecting operation, analog output holds for three minutes after the
detecting operation. (Concentration indication changes.)
14th Edition : Jul. 15, 2020