Thermo Scientific Alpha pH 800, Manual

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11.3 Appendix 3
Simple Explanation on the Function of Hysteresis
4 . 0 4.5 9.5 10.0 7.0
R E L A Y O F F
H Y S T E R E S I S B A N D
( D E F A U L T = 0 . 5 p H )
F O R W A R D D I R E C T I O N
R E V E R S E D I R E C T I O N
S P 1
S P 2
R E L A Y O N
S P 1 S e t t o L O
S P 2 S e t t o H I
The controller relay activates when the set-point is reached. 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.