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PUMP CONTROL
8. PUMP CONTROL
Pump control can be enabled, automatic control (AUTO) or disabled (off).
See SETUP section for further details on how to enable or disable pump control.
LCD backlight color indicates the pump control status:
• green - automatic control or in View menu mode
• yellow - disabled or in Edit menu mode
On the LCD screen, the pump status is displayed as below:
oFF, no dosing
AUTO, dosing
Startup Delay (Automatic Control Only)
When Startup Delay option is enabled, the controller is in Control Off mode for the set time; and the
LCD backlight color is yellow. The delay countdown will start upon powering the controller. At the end
of the timing the LCD backlight turns green and the control mode is automatic (Auto).
8.1. AUTOMATIC CONTROL TYPES
There are two automatic control types: On/Off (constant) control and Proportional control.
On/Off Control
With On/Off control type enabled in SETUP, the algorithm uses only “set point” and “hysteresis”, both
with user-selectable values. See SETUP section for further details.
Low control mode:
When the process EC drifts down and it reaches a low set point, it triggers the dosing
pump to turn on and fertilizer solution can be added to increase the EC. The pump will remain on until the
EC has increased to the set point value plus the hysteresis value. Then the pump will shut off.
High control mode:
Conversely, with High control mode, the process EC drifts upward until it reaches
a high set point. This triggers the dosing pump to turn on and a solution (purified water) can be added
to decrease the conductivity. The pump will remain on until the EC has decreased to the set point value
minus the hysteresis value. Then the pump will shut off.
The typical application uses a low control point with the addition of a fertilizer solution to increase
the EC value.