YSI 5200A
159
YSI 5200A
158
PID/PWM Control Actions
Interval, Gain, Reset Interval
Configuration of three control actions allows for greater control and stablity of
a particular environment. The control actions are Gain (page 159), Reset/Inteval
(page 158) and Interval (page 158). These three controls actions are closely inter-
related in terms of how the PID/PWM algothrium works. The objective is to tune
and configure these control actions in order that the corrective action (output
con-
trol on time
) performed by the 5200A results in system stability. That is, the system
will hold the set point without oscillating wildly (overshooting or undershooting
by significant amounts) over and under the set point. A large amount of ocillation
could cause irreparable damage to the system by dosing too large an amount, or too
small an amount, of a control dosing additive to the system stream.
AquaManager includes a PID Tuning tool which allows simulation of various control
action values and functions. The PID tuning tool should be helpful in mimicking
your system through simulation. The AquaManager PID Tuning tool is explained
in detail in the AquaManager Help System.
PID/PWM Interval control action
Range 1.00 to 999 (seconds)
Configure the interval control action to be the length of time a complete PID/PDW
control cycle takes. The control cycle includes both the control relay output on time
and the control relay output off time. Example: A 10 second control relay on time and
a 10 second control relay off time would represent a 20 second interval time. The 10
second control relay on time would be expected to decrease as the value reaches set
point. Interval, Reset interval and Gain control configurations are all interrelated in
the calculation of the control relay on time as the algothrium calculates the proper
corrective action.
PID/PWM Reset Interval control action
Range 0.00 to 100 (seconds)
Configure the Reset control action to be the rate at which the PID/PWM cycle re-
sets. In other words at what interval the past errors are erased and the PID/PWM
process begins a new cycle using new errors, and not past errors, in the PID/PWM
formula in calculating corrective action. Interval, Reset interval and Gain control
configurations are all interrelated in the calculation of the control relay on time as
the algothrium calculates the proper corrective action.
Configuring the 5200A
PID/PWM Gain control action
Range 0.01 to 10 %.
Gain is used to control the percentage of change in the output. Output increases with
greater gain. A high gain results in a large change in the output for a given change
in the error. A gain of “5” results in an additional 5% output relay on time for each
1% increase/decrease of the measurement. Tuning theory and industrial practice
indicate that gain should contribute the bulk of the output change. Interval, Reset
interval and Gain control configurations are all interrelated in the calculation of
the control relay on time as the algothrium calculates the proper corrective action.
PID/PWM Alarm System
Alarm values set the acceptable control range. Enable and configure system(s) alarm
to activate alarm output devices(s), view alarm icons, hear audible alarm and/or
receive alarm notifications sent via email or cell phone (SMS) - page 96. Config-
ure high and low alarm values to set alarm thresholds. Alarm system(s) becomes
active when value is
≤
low alarm value or ≥ high alarm value. Enabled alarm relays
energize if alarm condition exists for the general alarm hold off time. Alarm relays
are energized until one of the four softkeys
is pressed
regardless of sensor value. Pressing one of four softkeys resets the alarm system.
Alarm systems become active again if, after the alarm hold off period, the alarm
condition still exists. Alarm hold off is configured in the General Alarm menu.
When the General Alarm is enabled, (with or without enabled relay), the general
alarm system becomes active when any system alarm is active. See General Alarm
- 128.
Notes:
-
It is important to keep the 5200A at the Run Screen during normal opera-
tion. Alarm functionality (email alarms, activation of enabled alarm relays,
alarm icons, and buzzer) is suspended when 5200A is not at Run Screen.
-
Alarm icon(s) display at the Run Screen when alarm condition(s) exists for
longer than the general alarm hold off time. See Icons - page 70.
-
Press
at Run Screen to display active sensor and aux system relays.
-
to display events created by control and alarm relays - see Event Log
-
Alarm relays are not energized if the 5200A sensor value reads “Over” or
“Under.”
-
See Wire Relays - page 46 for information on wiring alarm output devices.
Configuring the 5200A
