Thermo Scientific Alpha DO 1000, Руководство пользователя, Страница: 28 / 48

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7.5.4 Selecting a Hysteresis (Dead Band) Value
Hysteresis prevents rapid contact switching if the value is fluctuating near the set
point. It does this by overshooting the set point value to a specified hysteresis value
(default is 0.20 mg/l or 2.5%). You can set the hysteresis value from 0.1 to 10 mg/l,
0.1 to 10 ppm or 1 to 10%.
Example: You have set your set point 1 (Lo) at 6.20 mg/l and your hysteresis limit
value is at 0.5 mg/l. If your measured value undershoots the low set point of 6.20
mg/l, 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 6.20 mg/l. When the value has increased to 6.70 mg/l, the relay, and hence
the pump will switch off.
1. Follow directions in 7.5.1 to enter Control
Relay mode. If you are in this mode, skip to
step 2.
2. Press the ENTER key 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 (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 7.5.5, or return to Measurement mode by pressing the
▲
or
▼
keys simultaneously (escape).
NOTE: Please refer to Appendix 3 for a graphical representation of
the Hysteresis.
7.5.5 Setting an On-Delay Time Lag
You can set as time delay for each relay, which stops the relay from switching on
the moment the set point is exceeded. This controller lets you set a 0 to 1999
seconds time delay before the relay activates.
1. Follow directions in 7.5.1 to enter Control
Relay mode. If you are in this mode, skip to
step 2.
2. Press the ENTER key. Scroll with the
▲
and
▲
keys until the upper display shows “0” time
and the lower display shows “On.d”.
3. Press the
▲
or
▼
keys to enter on-delay time
for Set point 1 (Set point 2). The controller will delay activation for the
number of seconds (0 to 1999) you select.
4. Press the ENTER key to confirm your selection.
O .
HOLD SETUP
0
Hys
mg/l
HOLD SETUP
0.20