Walchem WebMaster ONE Instruction Manual page 49

Relay 1- 8 Set Points
The set points available for each relay will vary depending upon the control mode selected. A
computer connection is required to change the control mode. The units of measure of some of the
set points will vary depending upon sensor input that may be assigned to the relay.
Set Point xxxxx (if control mode is any on/off set point, time proportional, target PPM)
Use the arrow keys to change the process value at which you want the relay to activate. The set
point value is limited to the range of the sensor input. Press Enter to accept the changes.
Dead Band xxxxx (if control mode is on/off set point)
Use the arrow keys to change 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 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. Press Enter to accept the new value.
Sample Period (minutes) xxxx (if control mode is time proportional feed)
Use the arrow keys to adjust the number of minutes used for the time proportional control sample
period. Any value between 1 and 1440 is acceptable. Press Enter to accept the new value.
Proportional Band xxxx (if control mode is time proportional feed)
Use the arrow keys to adjust the distance from the set point where the maximum output activation
time will occur. This parameter will be in the units of measure of the sensor input used to control
the relay. The acceptable range for this set point varies with the input. Press Enter to accept the
new value.
Duration (if control mode is intermittent sampling)
Use the arrow keys to set the minutes and press Enter to accept the new value. Then press Next to
move the cursor to the seconds and adjust with the arrow keys and press Enter to accept. Any
value between 10 sec and 60 minutes is acceptable. The duration is the time that the valve will be
open in order to get a fresh water sample to the electrode.
Hold Time (if control mode is intermittent sampling)
Use the arrow keys to set the minutes and press Enter to accept the new value. Then press Next to
move the cursor to the seconds and adjust with the arrow keys and press Enter to accept. Any
value between 10 sec and 10 minutes is acceptable. The hold time is the time that the valve will be
closed following a sample, but prior to the conductivity measurement. The hold time should ensure
that the sample is water and not steam.
Blowdown Time (if control mode is intermittent sampling)
Use the arrow keys to set the fixed blowdown time (in minutes) and press Enter to accept the new
value. Any value between 1 and 1440 minutes is acceptable. If the conductivity exceeds the set
point, the blowdown valve will activate for this time.
Interval Time (if control mode is intermittent sampling)
Use the arrow keys to set the time between samples (in minutes) and press Enter to accept the new
value. Any value between 5 and 1440 minutes is acceptable.
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