Front Panel Leds; Front Panel Switches; Dryer On / Off Switch; Percent Energy / Purge Savings Selector Switch - Gardner Denver DGH Series Instruction Manual

6.4.1 Front Panel LEDs

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Power on - green
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Alarm – red
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Service / maintenance reminder – amber
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Filters (pre, after, and pilot) service / maintenance
reminders - amber
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Operating mode (ISO class / manual (test) mode) – green
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Energy (purge) savings % – green
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Inlet switching and purge / repressurization valve status
(On = valve open; Off = valve closed) – green
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Left and right tower status (regenerating) - amber
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Left and right tower status (drying) - green
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Left and right tower pressure switch status (On = switch
closed; Off = switch open) - green

6.4.2 Front Panel Switches

The front panel contains four momentary-contact push button
switches. Refer to Figure 6-1, Front panel Overlay – Level 1
Controller for the appropriate icon associated with each switch.
Pushing on the overlay icon actuates the switch. Switching can
be affected remotely by wiring external pushbuttons to the J2
terminals located on the rear of the display board. Refer to
Section 6.2.4.

6.4.2.1 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 inlet-switching valves will open and
both purge-repressurization valves will close. 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 6.3.4 for additional information.
6.4.2.2 Operating Mode Selector Switch
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Four fixed-time cycles provide varying degrees of dryness
corresponding to ISO Classes 1, 2, 3, and 4.
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Manual cycle (test mode) is used for troubleshooting and
startup.
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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.
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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 6.4.2.4.
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Note: Button function is disabled when the remote
start / stop feature has placed the dryer in the cycle
interrupted (stop) mode. Refer to section 6.2.3.

6.4.2.3 Percent Energy / Purge Savings Selector Switch

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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.
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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 6.2.3.
6.4.2.4 Reset / Manual Advance Switch
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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.
6.4.3 Switching Failure Alarms
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When a tower does not de-pressurize, the Alarm LED,
Pressure Switch LED, and Tower Regenerating LED will
blink.
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When a tower does not re-pressurize, the Alarm LED,
Pressure Switch LED, and Tower Drying LED will blink.
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To extinguish the blinking LEDs, correct the fault condition
and press the alarm-reset button.
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Refer to Table 6-4.
6.5 Fixed Cycle Timing
Refer to Table 6-3 for the fixed cycle timing for the Level 1
Controller.
6.6 Event Sequence and Component Status
Refer to Table 6-4 for the event sequence and component status
for the Level 1 Controller.
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6. Controller – Level 1
6. Controller – Level 1