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Making Control Connections
™
Digital Ready
– Face & Bypass Control
Components Model AVS
Digital Ready is a factory installed pre-wired package of selected Direct
Digital Control (DDC) components. It facilitates the field hook up of a
DDC Unit Ventilator Controller (UVC) that is compatible with these
factory installed, pre-wired components, and capable of providing the
standard ASHRAE II cycle.
CAUTION
It is the responsibility of the Automatic Temperature Control
supplier to ensure the controls operate correctly and protect
the unit.
Digital Ready consists of the following components which are factory
wired and powered:
1
Unit Main Power "On-Off" switch – disconnects main power to
the unit for service. Non-fused power interrupt switch
2
Fuse(s) – fan motor, auto transformer and control transformer
have the hot line(s) protected by factory installed cartridge type
fuse(s).
3
Three (3) speed HIGH-MEDIUM-LOW-OFF motor fan speed
switch (SW2).
4
75 VA 24-volt NEC Class 2 transformer for 24-volt power
supply
5
Three 10-pole Europa type 16 awg terminal strips rated for 10
amps at 300 volts with nickel plated connectors and zinc plated
clamping screws (TB1, TB2, TB3).
6
Space available in left end compartment, approximately 8" x 21"
(203mm x 533mm) for UVC mounting (by others)
Figure 112 - Component Locations (Vertical Floor Unit Shown)
5
6
13
12
Page 42 of 60
10
Outdoor Air Opening (Sensor)
11
Wired to the Terminal Strips:
7
Interface with the fan motor start/stop relay, (R4) in electric
connection box.
8
Interface with a factory installed Low Air Temperature Limit (T6
- Freezestat). Cuts out below 38
F±2
o
o
above 45
F. Responds when any 15% of the capillary length
senses these temperatures. Wired so that upon T6 cut out, the outside
air damper (A1) closes, the hot water valve opens and the 24 volt
power supply to the terminal strip (T6 Sig) is interrupted.
9
Discharge Air Temperature Sensors – (S2) 10 K ohm NTC (Negative
Temperature Coefficient) and 1 K ohm PTC (Positive Temperature
Coefficient). Located on the second fan housing from the right to
sense discharge air temperatures.
10 Room Temperature Sensors - (S1) 10K ohm (NTC) and 1 K ohm
(PTC). The unit mounted sensors are located in the unit sampling
chamber (front center section), where room air is constantly
drawn through for prompt response to temperature changes in the
room.
11 Outdoor Air Temperature Sensors - (S3) 10K ohm (NTC) and 1
K ohm (PTC). The sensors are located in the outdoor air section
of the unit before the outdoor air damper.
12 Direct coupled, proportional control (2 to 10 VDC or 4 to 20 mA)
Outdoor Air/Return Air Damper Actuator (A1) (spring return).
13 Direct coupled, proportional control (2 to 10 VDC or 4 to 20 mA)
Face and Bypass Damper Actuator (A3) (non-spring returned).
14 Interface from the terminal board with one or two End of Cycle
DDC valves with spring return actuators (by others) (Not Shown)
providing 24-volt power. Open/shut signal from UVC (by others).
15 24-volt power wiring harness from the right to left-hand end
compartment through the built-in metal wire raceway terminating
at three terminal blocks.
16 Low Refrigerant Temperature Sensor (T4-capillary sensor), helps
protect against abnormally low evaporator coil temperatures. Direct
Expansion (DX) units only (Not shown).
15
9
8
F±2
o
o
F and automatically resets
Motor
7
2
3
1
4
IM 817-4
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