Metex 2200R ORP Analyzer/Controller - Manual (Page 18)

Model 2200R Page 16
a) Enter the menu by pressing CALL, proceed by pressing CALL until the RELAY
A DEADBAND LED is illuminated. Now use the arrow keys to make the display
read the desired value. Press ENTER. The display will flash until ENTER is
pressed again to confirm the value.
b) Press RUN, to place the instrument on line, or press CALL for another menu
selection.
5.7 Control Relay B Setpoint / Deadband
3.5.1 Control Relay B is configured the same as Relay A. (Refer to Sec. 5.5 / 5.6) As
shipped from the factory, Control Relay B is configured to control increasing ORP.
However, you may change the direction of control by changing the position of the
DIP switch. (Refer to Section 4.7)
5.8 Relay B Deadband
3.5.1 Relay B Deadband is configured in the same way as Relay A Deadband. See
Section 5.6.
NOTE: A deadband setting on the wrong side of the setpoint is an invalid entry which will
be indicated by the LED flashing when you return to RUN. To correct, return to the
menu and change the deadband setting or, if the direction of control is the problem,
change the position of the relevant DIP switch. Refer to Sections 4.7 and 5.6.
5.9 Bi-directional Control
5.9.1 The two control relays can be used for bi-directional control, best explained by an
example. In this example the ORP must be maintained between 600 and 800. One
possible configuration would be as follows:
Control Relay A
• Connect Pump to NO and COM of Relay A
• Set to Control Decreasing ORP Dip Switch #4 Bank S1 “On Position”
• Set Control Relay A Setpoint at 600 mV
• Set Control Relay A Deadband at 650 mV
Control Relay B
• Connect Pump to NO and COM of Relay B
• Set to Control Decreasing ORP Dip Switch #2 Bank S2 “Off Position”
• Set Control Relay B Setpoint at 800 mV
• Set Control Relay B Deadband at 750 mV
With the above configuration Relay A will control the addition of caustic. The pump
will turn on if the ORP falls to 600 mV ORP and will stay on until the ORP rises
above 650mV. Relay B will control the other pump. The acid pump will turn on if the
ORP rises to 800mV ORP and will stay on until the ORP falls to 750 mV. Therefore
the ORP will always remain between 600 mV and 800 mV.