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5. CONTROLLERS – GENERAL
5.1 Overview
The solid-state dryer controller is located in a polycarbonate, NEMA
Class 4/4X, IP66 rated electrical enclosure mounted to a center panel
located between the two desiccant towers. Controls are available in
three functional levels. The Timer Controller offers a fixed-time cycle
that provides a dew point corresponding to ISO compressed air quality
class 2. Both the Level 1 and Level 2 controls offer four fixed-time
cycles that provide dew points corresponding to ISO compressed air
quality classes 1 through 4. A key difference between the Level 1 and
Level 2 controls is the way in which they address energy savings. When
inlet flow is less than the adjusted rated capacity of the dryer, average
purge air requirements are reduced. This reduction can translate to
energy savings at the air compressor.
The Level 1 Controller offers 8 selectable fixed-cycle Energy (purge)
Saver modes (0% to 70% in 10 % increments) to reduce purge time
to match the load on the dryer.
Level 2 Controllers feature the Automatic Purge Saving System
(APSS) as described in Sections 3.2 and 3.4. When Level 2 Controllers
are operated in demand rather than fixed cycle modes, the APSS
automatically adjusts to dryer loading and extends drying time when
possible. Average purge use is thus automatically reduced.
A feature-by-feature comparison of each controller can be found in
Table 5-1.
Table 5-1
Feature Comparison
(continued on next page)
Desiccant Dryer Controllers
Timer
Controller
Level 1
Fixed Cycle Only
Level 2
Fixed Cycle
and APSS
Category
Feature
General
AC Input Voltage: 100-240 VAC, 50-60 Hz (See NOTE 1)
•
AC Input Voltage: 85-264 VAC, 47-63 Hz (See NOTE 1)
•
•
DC Input Voltage: 11.5-28 VDC (See NOTE 1)
•
•
Auxiliary power terminals (See NOTE 2)
•
•
Solenoid valve coil voltage
12 VDC
12 VDC
12 VDC
NEMA 4/4X, IP 66 electrical enclosure rating
•
•
•
Soft on/off switch with two power recovery modes (See NOTE 3)
•
•
Tower status LEDs (amber=drying)
•
Tower status LEDs (green=drying, amber=regenerating)
•
•
Process valve status LEDs (on=valve open, off=valve closed)
•
•
Operating mode LEDs (see next category for number of modes)
•
Alarm LED (red)
•
•
Voltage-free alarm contacts, 5A rating
•
•
Alarm reset switch (mounted on front panel)
•
•
Service reminder LEDs (See NOTE 4)
•
•
Vacuum fluorescent text display
•
Operating Modes
(See NOTE 5 and
NOTE 7)
60-150 or 120-250 psig MOP (selectable via jumper on circuit board)
•
•
ISO Class 1 (-100°F/-73°C PDP) - fixed cycle (4 minute)
•
•
ISO Class 2 (-40°F/-40°C PDP) - fixed cycle (10 minute)
•
•
•
ISO Class 3 (-4°F/-20°C PDP) - fixed cycle (16 minute)
•
•
ISO Class 4 (+38°F/+3°C PDP) - fixed cycle (24 minute)
•
•
Fixed Cycle Energy (purge) Saver (See NOTE 6)
•
Manual Cycle (test mode)
•
•
ISO Class 2 (-40°F/-40°C PDP) - demand cycle
•
ISO Class 3 (-4°F/-20°C PDP) - demand cycle
•
ISO Class 4 (+38°F/+3°C PDP) - demand cycle
•
Digital I/O
Controlled shutdown and restart (upon user supplied contact closure)
•
•
Tower pressure switches (2)
•
•
High Humidity Alarm
Optional
Filter monitor alarm (1 or 2 filters)
Optional
Electric drain alarm (1 or 2 filters)
Optional
Electric drain test (1 or 2 filters)
Optional
Analog I/O
(12 bit accuracy)
Thermistors (4)
•
Communication
RS232 communication port
•
•
