Emerson 54e pH/ORP Setpoint +07.00 pH, Time period 30 sec, URV 2.00 pH, LRV 0.00 pH

MODEL 54e pH/ORP	SECTION 5.0
	SOFTWARE CONFIGURATION

5.7 CHANGING ALARM PARAMETERS (continued)

Alarm Setup Parameters (for TPC Alarms)

Setpoint: +07.00 pH

Proportional: 100.0%

Integral: 0 sec

ExitEdit

Derivative: 0.0%

Time period: 30 sec

URV: 2.00 pH

ExitEnter

URV: 2.00 pH

LRV: 0.00 pH

Relay default: None

ExitEnter

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".

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