Thermo Fisher Scientific Alpha COND 560 - Manual (Page 45)

39
10.2 Appendix 2
Graphical Representation of the Function of Hysteresis
100
RELAY OFF
Forward Direction
Reverse Direction
SP1 SP2
RELAY ON
SP1 = 100 & Set to LO
SP2 = 1900 & Set to HI
µS
µS
µS
120 1880 1900
HY
S
T
E
R
E
S
IS
B
A
N
D
De
fa
u
lt =
2
0
µS
HY
S
T
E
R
E
S
IS
B
A
N
D
De
fa
u
lt =
2
0
µS
The relay of the conductivity 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 1900 µS and your hysteresis value at
20 µS. If your measured value overshoots 1900 µS, the controller’s relay activates.
The actions of the external device will cause the solution’s conductivity to drop. The
relay will deactivate, when the conductivity value drops below 1880 µS.