Gardner Denver DGH Series Instruction Manual page 24

7.4.1 Front Panel LEDs
• Power on - green
• Alarm – red
• Service / maintenance reminder – amber
• Filters (pre, after, and pilot) service / maintenance reminders
- amber
• Operating mode (ISO class / manual (test) mode) – green
• Energy (purge) savings % – green
• Purge / repressurization valve status (On = valve open; Off = valve
closed) – green
• Left and right tower status (regenerating) - amber
• Left and right tower status (drying) - green
• Left and right tower pressure switch status (On = switch closed;
Off = switch open) - green
7.4.2 Front Panel Switches
The front panel contains four momentary-contact push button switches.
Refer to Figure 7-1, Front panel Overlay – Standard Controllers for the
appropriate icon associated with each switch. Pushing on the overlay
icon actuates the switch. Switching can be affected remotely by wiring
external push-buttons to the J2 terminals located on the rear of the
display board. Refer to Section 7.2.4.
7.4.2.1 Dryer On / Off Switch
This switch is used to turn the dryer on (run) or off (stop).
CAUTION: In the event of a loss of power, either intentional or
unintentional, both purge-repressurization valves will close. On
standard pressure models 4100 & 5400 and high pressure models
40 through 450, both inlet-switching valves will open. A tower that
is actively purging when the power off button is actuated will be
subjected to a rapid repressurization that can lead to fluidization
and subsequent abrasion of the desiccant bed. Ideally, dryers
should be powered off at the end of any half cycle when both
desiccant towers are at full operating pressure.
Power recovery after an external loss of power is affected by the
position of control board jumper J4 (power recovery mode). Refer to
Section 7.3.4 for additional information.
7.4.2.2 Operating Mode Selector Switch
• Four fixed-time cycles provide varying degrees of dryness
corresponding to ISO Classes 1, 2, 3, and 4.
• Manual cycle (test mode) is used for troubleshooting and
startup.
• The operating mode can be changed at any time. Press the
switch repeatedly until the desired mode's LED is blinking. The
LED for the current mode remains illuminated until the end of
the current half-cycle, at which time the new selection becomes
active. At this time, the LED for the new selection switches from
blinking to illuminated, and the LED for the previous selection is
extinguished.
• To select Manual (test) cycle, press and hold the switch for
approximately 2 seconds. The current ISO Class LED will remain
illuminated and the Manual cycle mode LED will illuminate.
When in the Manual cycle mode, the dyer can be advanced one
step at a time using the reset/manual advance switch. Refer to
section 7.4.2.4.
• Note: Button function is disabled when the remote start / stop
feature has placed the dryer in the cycle interrupted (stop) mode.
Refer to section 7.2.3.
7.4.2.3 Percent Energy / Purge Savings Selector Switch
• If dryer is operated at less than maximum flow capacity a
reduction in purge air usage may be possible. Eight settings (0%
to 70% in 10% increments) reduce the purge time to match the
load on the dryer. Refer to the Operation Section to determine
maximum inlet flow capacity at operating pressure. The Energy
savings selection can be changed at any time. Press the switch
repeatedly until the desired selection's LED is blinking. The LED
for the current selection remains illuminated until the end of the
current half-cycle, at which time the new selection becomes
active. At this time, the LED for the new selection switches from
blinking to illuminated, and the LED for the previous selection is
extinguished.
• Example: If the maximum adjusted allowable inlet flow to a
dryer was 1000 SCFM, but the actual flow to the inlet was only
300 SCFM, then the Energy Saving setting would be 100%-
((300/1000)*100%)=70%. At 300 SCFM, only 30% of the dryer
capacity is being utilized. Average purge requirements and the
related energy needed to compress that purge air can be reduced
by 70%.
• NOTE: Button function is disabled when the remote start / stop
feature has placed the dryer in the cycle interrupted (stop) mode.
Refer to section 7.2.3.
7.4.2.4 Reset / Manual Advance Switch
• This switch is normally used to reset an alarm or service reminder.
When the Manual cycle (test) mode is selected, this switch is used
to advance through the operating cycle one step at a time.
NOTE: Allow towers to fully repressurize before advancing to
tower switchover.
7.4.3 Switching Failure Alarms
• When a tower does not de-pressurize, the Alarm LED, Pressure
Switch LED, and Tower Regenerating LED will blink.
• When a tower does not re-pressurize, the Alarm LED, Pressure
Switch LED, and Tower Drying LED will blink.
• To extinguish the blinking LEDs, correct the fault condition and
press the alarm-reset button.
• Refer to Table 7-4.
7.5 Fixed Cycle Timing
Refer to Table 7-3 for the fixed cycle timing for the Standard
Controllers.
7.6 Event Sequence and Component Status
Refer to Table 7-4 for the event sequence and component status for
the Standard Controller.
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