EUTECH INSTRUMENTS alpha-pH 2000D, Instruction Manual, Page: 26 / 50

Instruction Manual
α
lpha-pH2000D
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6.4 Control Relay A / Relay B (SP1/SP2) sub-function
The SP1 sub-function determines the operating parameters for Relay A; while SP2 defines the
operating parameters for Relay B. Since these groups have the same set-up parameters, they
are described together.
SETUP
HOLD
SETUP
HOLD
SETUP
HOLD
SETUP
HOLD
SETUP
HOLD
SETUP
HOLD
hi
1
2
5 6
3
3
4
ENT
ENT
ENT
ENT
ENT
ENT
ENT pH
pH
SETUP
HOLD
1. Select the “SP1” (Relay A) or “SP2” (Relay B) sub-function, then press the ENT key.
2. Setting set point value: press the ▲ or ▼ key to enter the value for set point 1 (set point 2)
at which your controller will activate. Press the ENT key to confirm your setting.
3. Selecting relay function: press the
▲
or
▼
key to select the desired relay function (“LO”=
low or “HI”= high). Press the ENT key to confirm your selection.
Note: This parameter lets you choose the relay function. Select “LO” to activate the
relay when the pH/ORP value undershoots the set point; select “HI” to activate the
relay when the value overshoots the set point. SP1 and SP2 can be selected as
“Lo/Lo”, “Lo/Hi”, “Hi/Lo”, or “Hi/Hi”.
4. Setting a hysteresis value: press the ▲ or ▼ key to select the desired hysteresis (setting
range: 0.1 to 1.0 pH, 10 to 100mV or 1 to 10%) for set point 1 (set point 2). Press the ENT key
to confirm your setting.
Note: Hysteresis prevents rapid contact switching if your value is fluctuating near
the set point. Please refer to Appendix 3 for a graphical representation of the
hysteresis.
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 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.