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MODEL 54e pH/ORP SECTION 5.0
SOFTWARE CONFIGURATION
5.7 CHANGING ALARM PARAMETERS (continued)
Alarm Setup Parameters
(for TPC Alarms)
4b. Menu Item Options
Set point -2 to 20 pH, -1400 to +1400 mV(ORP/Redox)
Proportional 0-299.9 %
Integral 0-2999 sec
Derivative 0-299.9 %
Time period 10-2999 sec
URV -2 to 20 pH, -1400 to +1400 mV(ORP/Redox)
LRV -2 to 20 pH, -1400 to +1400 mV(ORP/Redox)
Relay Default None/Close/Open
These parameters are available for alarms that have been config-
ured as TPC alarms in step 3. Parameters can be adjusted using the
same technique as in step 4a, by highlighting the desired item and
pressing the Edit 4 key. Once Edit has been pressed, change the
item as needed and then press Save 4 to store the value.
"Setpoint" is usually the desired value at which the process is being
controlled, typically the alarm will not be on very much when the
process is at this value. This setpoint is also accessible in the
Program Menu under "Alarm Setpoints" (see Section 5.2)
"Proportional" is short for Proportional Band and indicates the
range over which control is being used. It is the opposite of the
process gain. Smaller values provide tighter control.
"Integral" is the number of seconds over which deviations from the
setpoint are integrated to remove continuing offsets. Smaller values
provide higher response.
"Derivative" is a form of control that resists all changes in readings.
Higher readings increase the derivative function. Use caution in set-
ting the derivative value to prevent process oscillation.
"Time period" is the cycle time for the TPC control. One cycle con-
sists of an energized (relay on) time and an deenergized (relay off)
time. The relative amounts of on time and off time depends on the
reading and the other settings listed here.
"URV" is the deviation from the setpoint that results in the alarm
being on all the time.
"LRV" is the deviation from the setpoint that results in the alarm being
off all the time. This should be set to 0.00.
EXAMPLE 1: A setpoint of 6 pH with URV of +2.0 pH and LRV of 0.0
pH, a time period of 30 seconds. When the pH is 7.0, the relay will
be on (7-6)/(2-0) = 50% of the time, 15 seconds each time. If the set-
point is changed to 6.5 pH, the relay will be on 7-6.5/(2-0) = 25% of
the time. The relay would then be on for 7 seconds and off for 23 sec-
onds.
"Relay Default" determines how the relay will act if there is a fault or
hold condition. Each alarm can be forced on (Close), off (Open) or
can remain unchanged (None). The original configuration is "None".
Setpoint: +07.00 pH
Proportional: 100.0%
Integral: 0 sec
Exit Edit
Derivative: 0.0%
Time period: 30 sec
URV: 2.00 pH
Exit Enter
URV: 2.00 pH
LRV: 0.00 pH
Relay default: None
Exit Enter