Instruction manual

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Other (4-20 mA input 7) should be selected if you will control the ORP relay based on a signal
from a transmitter that is connected to 4-20 mA input 7. This option is only possible if your
controller is equipped with the analog input option card.
Current ORP
(only appears if ORP Control Mode is selected as Direct ORP Sensor)
Displays the current ORP reading from the electrode.
Set Point
Type in the text box the ORP value at which the relay will close (to start a pump, or open a
solenoid valve) in order to correct it. Any value between –1500 and 1500 is acceptable (if based on
direct ORP sensor). If the control mode is based on a 4-20 mA input, then the set point value is
limited to the range of the 4-20 mA input. Click on the link called Scaling to set the range of the 4-
20 mA input.
Status
This menu is for information only, and displays whether the ORP output is “Off” or “On” and if
on, for how much time, or if any alarm conditions exist. Possible status messages are Off,
Off/Manual, On/Time counting up (for adds based on ORP input signal) and On/Time counting
down/Hand (for manual activation). Possible error messages are Time Out (output has been on too
long), No Flow and Interlock. See section 8.1 for a complete description of error messages.
Reset Timeout
There is also a button called “Reset Timeout” which is used to reset the output if it has been
activated for longer than the time limit imposed in the “Output Time Limit” menu described
below.
Custom Name
This menu allows you to call the output another name if desired. Type the new name in the text
box.
Dead Band
Type in the text box the ORP value away from the set point at which the pump will stop running.
For example, if you are forcing the ORP higher, your set point is 400 mV, and your dead band is
10 mV, then the hypochlorite pump will start at 399 mV and stop at 405 mV. The purpose of the
dead band is to prevent rapid cycling of the relay open and closed, which can shorten its life. The
dead band should be set for the lowest value that still prevents the relay from chattering.
Control Direction
Click on the radio button that describes which direction you want to move the ORP. If you plan on
adding an oxidizer to increase the ORP, select “Force Higher”. If you plan on adding a reducing
agent to decrease the ORP, select “Force Lower”.