7. Controller – Level 2
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7. Controller – Level 2
Time (refer to Table 7-4)
t0
t1
t2
t3
t4
t5
t6
t7
t8
Process valve name
(Process valve state
w/ de-energized
pilot solenoid valve)
Left Tower Drying
Right Tower Regenerating
Half Cycle
Right Tower Drying
Left Tower Regenerating
Half Cycle
Left purge valve
(normally closed)
Pilot Energized
(open)
Left inlet valve
(normally open)
Pilot Energized (closed)
Right inlet valve
(normally open)
Pilot Energized (closed)
Right purge valve
(normally closed)
Pilot Energized
(open)
Normal status of pressure switches
Left tower
pressure switch
closed
closed
closed
closed
closed
closed
closed for < 5
sec. then open
open at t7,
closed before t8
Right tower
pressure switch
closed
closed
closed for < 5
sec. then open
open at t3,
closed before t4
closed
closed
closed
closed
Pressure switch status that causes an alarm
Left tower drying
Low tower pressure
a
open
1
open
1
Left tower regenerating
Fail to de-pressurize
b
closed
1
Left tower regenerating
Fail to re-pressurize
c
open
2
Right tower drying
Low tower pressure
d
open
1
open
1
Right tower regenerating
Fail to de-pressurize
e
closed
1
Right tower regenerating
Fail to re-pressurizef
open
2
Note
Stop cycle on
fault?
Comments
1: Check for fault condition at 15, 25,
35,... seconds into the half-cycle
no
If the fault condition is clear for 1 cycle: the alarm LED stays on (without blinking) and the alarm message continues to
be displayed. Once the fault condition is clear, pressing the reset button will clear the alarm LED and message.
2: Check for fault condition just before
the end of the half-cycle
yes
If the fault condition clears: tower cycling resumes and the alarm LED stays on (without blinking). Once the fault
condition is clear, pressing the reset button will clear the alarm LED and message.
a: Blink the Alarm LED and display the following text message: Alarm + Left Tower Low Pressure
b: Blink the Alarm LED and display the following text message: Alarm + Left Tower Regene High Pressure
c: Blink the Alarm LED and display the following text message: Alarm + Left Tower Regene Low Pressure
d: Blink the Alarm LED and display the following text message: Alarm + Right Tower Low Pressure
e: Blink the Alarm LED and display the following text message: Alarm + Right Tower Regene High Pressure
f: Blink the Alarm LED and display the following text message: Alarm + Right Tower Regene Low Pressure
Table 7-5
Event Sequence and Component Status – Level 2 Controller