Thermo Fisher Scientific Alpha pH 560 - Manual (Page 48)

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Thermo Scientific Alpha pH 560 43
The relay of the pH Controller activates when the set-point is reached
(forward direction). In the reverse direction, it does not de-activate
when the value reaches the set-point. Instead, it continues to be active
till the value reaches the amount set by the Hysteresis band.
Example: You have set your high set point at pH 10.0 and your
hysteresis value at pH 0.5. If your measured value overshoots pH 10.0,
the pH Controller’s relay activates. The actions of the external device
will cause the solution’s pH to drop. The relay will deactivate, when the
pH value drops below 9.5 pH.
Control characteristics of pH Controller used as a limit value switch
Figure 0–28.
Appendix 2
Graphical
Representation of
the Function of
Hysteresis
Appendix 3
General Instructions
Concerning
Controller Settings