Carrier WeatherExpert 50LC14, Installation Instructions Manual, Page: 57 / 84

57
ECONOMISER HARDWARE
Actuators
The EconoMi$er
®
X damper actuators are direct-coupled types
with spring-return. Power is 24-v from the W7220 outputs. Range
of rotation is 95 degrees; timing for full-range movement is
90 seconds to drive open in normal operation, 30 seconds in Test
Mode and 25 seconds for spring return.
These actuators are S-bus enabled. The S-bus is a proprietary local
equipment network that connects the W7220 controller, one
S - enabled actuator and up to three S-type enthalpy sensors on a
two-wire communication network. The S-bus is polarity-
insensitive. Devices attached to the S-bus are automatically recog -
nized by the controller.
Actuator command position is defined in a 2-10 vdc value. 2.0-v is
outside air damper position fully closed (0% open); 10.0-v is
damper position fully open (100% open). See Table 11 to correlate
control voltage values to outside air damper opening percentage.
These units use a 5-Nm (44 lb-in.) torque model, Honeywell
Series MS3105K actuator.
Table 11 — Actuator Voltage vs. Damper Position
Supply Air Temperature Sensor
The W7220 controller uses a 20k ohm analog sensor for Supply
Air Temperature (SAT). The thermistor is attached to a ring termi -
nal. The ring terminal is attached to the unit’s supply fan housing,
downstream of the unit’s indoor coil. The SAT sensor is connected
to the W7220 input terminals marked MAT. See Table 12 for sen -
sor resistance to temperature correlations.
The W7220 controller requires a valid signal from its SAT channel
in order to function. If the SAT connection to the W7220 is lost,
the W7220 will initiate an alarm condition immediately. No econ -
omizing operation will be permitted until this alarm is cleared.
Table 12 — SAT/OAT Sensor Characteristics
Outside Air Temperature Sensor
EconoMi$er
®
X systems equipped with outdoor dry bulb tem -
perature changeover control include a 20k ohm analog sensor to
measure Outdoor Air Temperature (OAT). This is the same sensor
used for the SAT function; see Table 12 for resistance vs tempera -
ture characteristics.
The OAT sensor is attached to the outside air damper frame. It is
connected to the W7220’s OAT input terminals.
If an accessory enthalpy sensor is added to an EconoMi$er X sys -
tem with factory dry bulb changeover, disconnect this OAT sensor
wiring at the W7220’s OAT input terminals.
Enthalpy Control Sensor Configuration
The W7220 economizer control system can accommodate up to
three S-bus enthalpy sensors. On EconoMi$er X models with fac -
tory-installed Enthalpy Changeover control, one S-bus sensor is
provided in the economizer outdoor section. Additional sensors
may be added to measure return air and discharge air conditions.
The enthalpy control sensor (P/N HH57AC081) communicates
with the W7220 economizer controller on the two-wire local
equipment network bus (S-bus) and can either be wired using a
two-pin header or using a side connector. This sensor is used for
all OAT (Outdoor Air Temperature), RAT (Return Air Tempera -
ture) and DAT (Discharge Air Temperature), depending on how
its three-position DIP switch is set.
Use Fig. 76 and Table 13 to locate the wiring terminals for each
Enthalpy Control sensor.
Use Fig. 76 and Table 14 to set the DIP switches for the desired
use (location) of the sensor.
Fig. 76 — Enthalpy Control Sensor — Dimensions
and DIP Switch Locations
Table 13 — Enthalpy Control Sensor Wiring
Terminations*
*Terminals are polarity insensitive.
Vdc % OPEN VDC % OPEN VDC % OPEN
2.0
0 4.8 35 7.6 70
2.4 5 5.2 40 8.0 75
2.8
10 5.6 45 8.4 80
3.2 15 6.0 50 8.8 85
3,6
20 6.4 55 9.2 90
4.0 25 6.8 60 9.6 95
4.4
30 7.2 65 10.0 100
DEG C OHMS DEG F OHMS
–30
415,156
–20
386,130
–25 301,540 0 193,070
–20
221,210
20
101,820
–15 163,834 32 70,200
–10
122,453
40
55,420
–5 92,382 45 47,771
0
70,200
50
41,258
5 53,806 55 35,725
10
41,561
60
31,035
15 32,341 65 27,069
20
25,346
70
23,719
25 20,000 77 20,000
30
15,886
80
18,473
35 12,698 100 11,544
40
10,212
120
6,768
45 8,261
50
6,720
TERMINAL
TYPE DESCRIPTION
NBR LABEL
1 S-BUS S-BUS
S-Bus Communications
(Enthalpy Control Sensor Bus)
2
S-BUS S-BUS
S-Bus Communications
(Enthalpy Control Sensor Bus)
2-1/64 (55)
51/64 (21)
4-1/4 (108)
2-3/4 (70)
NOTE : Dimensions are in inches. Dimensions in ( ) are in mm.