ATI
Q46UV UV254/Turbidity Monitor
Part 5 - Configuration
34
O&M Manual
Rev-D (11/19)
*A Setpoint
This function establishes the trip point for relay A. The entry value is
limited to a value within the range specified in “Set Range”. Use the
LEFT arrow key to select the first digit to be modified. Then use the UP
and LEFT arrow keys to select the desired numerical value. Press
ENTER to store the new value.
*A Hysteresis
This function establishes the hysteresis, or “deadband”, for Relay A.
Hysteresis is most often used to control relay chattering; however, it may
also be used in control schemes to separate the ON/OFF trip points of
the relay. Press ENTER to initiate user entry mode, and the value will
flash. Use the arrow keys to modify value. Press ENTER to store the
new value.
*A Delay
This function places an additional amount of time delay on the trip point
for relay A. This delay is in addition to the main delay setting for the
controller. The entry value is limited to a value between 0 and 999
seconds. Press ENTER to initiate user entry mode, and the value will
flash. Use arrow keys to modify value; range is 0 to 999 seconds. Press
ENTER to store the new value.
*A Phasing
This function establishes the direction of the relay trip. When phase is
HI, the relay operates in a direct mode. Therefore, the relay energizes
and the LCD indicator illuminates when the oxygen value
exceeds
the
setpoint. When the phase is LO, the relay energizes and the LCD
indicator illuminates when the oxygen level drops
below
the setpoint.
The failsafe setting does have an impact on this logic. The description
here assumes the failsafe setting is OFF. Press ENTER to initiate user
entry mode, and the entire value will flash. Use the UP arrow key to
modify the desired value; selections include
HI
for direct operation or
LO
for reverse operation. Press ENTER to store the new value.
See Figure 19 below for a visual description of a typical control relay application.
Figure 19 - Control Relay Example, Hysteresis & Phase Options
When value rises to
≥
1.000 ppm, relay closes.
When value falls to
≤
0.950 ppm, relay opens.
When value rises to
≥
1.050 ppm, relay opens.
When value falls to
≤
1.000 ppm, relay closes.
}
1.000 ppm
0.950 ppm
PHASE: HI
ON
HYSTERESIS
OR
“DEAD BAND”
X
OFF
}
1.050 ppm
1.000 ppm
PHASE: LO
OFF
HYSTERESIS
OR
“DEAD BAND”
X
ON
Settings:
Setpoint: 1.000 ppm
Hyst:
0.050
Delay:
000
Failsafe: OFF
