Walchem WebMaster ONE Instruction Manual page 89

Status
This menu is for information only, and displays whether the output is "Off" or "On" and if on, for
how much time, as well as any alarm conditions. Possible status messages are; Off, Off/Manual,
On/Time counting up (if activated based on sensor input), Off/Time counting down or On/Time
counting down/Hand (for manual relay activation). Possible error messages are Timeout and
Interlock. See section 8.1 for a complete description of error messages.
Reset Timeout
There is 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 rename the output if desired. Type the new name into the text box.
Set Point
Type in the text box the process value at which you want the relay to activate. The set point value
is limited to the range of the assigned input.
Control Direction
Click on the radio button to select between "Force Lower" or "Force Higher".
Dead Band
Type in the text box the process value away from the set point at which the relay will deactivate.
For example, if you are forcing the conductivity lower, your set point is 2000 S/cm, and your
dead band is 100 S/cm, then the relay will activate at 2001 S/cm and deactivate at 1900 S/cm.
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.
Mutual Interlocks
Click the check boxes to select or de-select the relays and analog output control outputs that you
want to be prevented from turning ON if this output relay is already ON. If you do not need any
other output to shut off when this relay turns on, UNCHECK all boxes. The selection is mutually
exclusive, meaning that if Relay 2 has Relay 4 interlocked, then R2 won't turn on if R4 is already
on, and R4 won't turn on if R2 is already on. This feature should be used with caution since it can
potentially delay a chemical addition for a long time.
Output Time Limit
Type in the text box the maximum amount of time that the relay can be continuously activated
before the controller deactivates the relay and activates an Output Time Limit alarm. This is
intended to prevent the output from running out of control if the input fails in such a way that it
will never deactivate the relay.
Note that the relay will not activate again until someone resets the timer!
It will take some experience to find out what the normal output on-time will be. If the relay cycles
open and closed under worst case conditions in 30 minutes, you may want to set the Output Time
Limit at 60 minutes.
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