Thermo Fisher Scientific Alpha COND 1000 - Manual (Page 24)

Operating Instructions Thermo Scientific Alpha COND 1000
16
7.3.3 Choosing High or Low set points
Select a low set point to activate controller when the conductivity value
undershoots the low set point; select a high set point to activate controller when the
value overshoots the high set point. Using both SP1 and SP2, you can select lo/lo,
lo/hi, hi/lo, or hi/hi set points (Default: SP1 = Lo; SP2 = Lo).
1) Follow directions in 7.3.1 to enter Control Relay mode.
2) Press the ENTER key. Scroll with the ▲ or ▼ keys until the upper display
shows Lo or Hi (for low or high set point) and the lower display shows SP1 (or
SP2).
3) Press the ▲ or ▼ keys to select low (lo) or high (hi) set point for SP1 (or SP2).
4) Press the ENTER key to confirm your selection.
5) Proceed to 7.3.4, or return Measurement mode by pressing the ▲ and ▼ keys
simultaneously (escape).
7.3.4
Selecting a hysteresis (dead band) value
Hysteresis prevents rapid contact switching if your value is fluctuating near the set
point. It does this by overshooting the set point value to a specified hysteresis value
Example: You have set your set point 1 (Lo) at 100.0
μS and your hysteresis limit
value is at 20
μS. If your measured value undershoots the low set point of 100.0 μS,
the controller’s relay activates, which in turn activates an external device such as a
pump or valve. The actions of the external device will cause the value to rise above
100.0
μS. When the value has increased to 120.0 μS, the relay, and hence the
pump will switch off.
Default hysteresis value in the full scale conductivity range of 2,000 µS (see
Appendix 2) is 20 µS. You can set the hysteresis value from 0 to 10% of the full
scale conductivity range.
1) Follow directions in 7.3.1 to enter Control Relay
mode.
2) Press the ENTER key. Scroll with the ▲ or ▼ keys
until the upper display shows the hysteresis (dead
band) value and the lower display shows “HYS”.
3) Press the ▲ or ▼ keys to enter your hysteresis
value for Set point 1 (or Set point 2). Your controller will activate at the value
you select. Note: All settings for SP1 and SP2 are completely independent of
each other.
4) Press the ENTER key to confirm your selection.
5) Proceed to 7.3.5, or return to Measurement mode by pressing the ▲ and ▼
keys simultaneously (escape).
NOTE: Please refer to Appendix 3 for a graphical representation of the Hysteresis.
6
Hys
μ S
HOLD SETUP
20