Honeywell W7750A User Manual
EXCEL 10 W7750A,B,C CONSTANT VOLUME AHU CONTROLLER
74-2958—1
32
Fig. 20. Wiring layout for two singly terminated
L
ON
W
ORKS
® Bus segments.
NOTE:
See the L
ON
W
ORKS
Bus Termination Module section
for wiring details.
IMPORTANT
Notes on communications wiring:
•
All field wiring must conform to local codes and ordi-
nances or as specified on installation wiring dia-
grams.
nances or as specified on installation wiring dia-
grams.
•
Approved cable types for L
ON
W
ORKS
Bus communi-
cations wiring is Level IV 22 AWG (0.34 mm
2
) ple-
num or non-plenum rated unshielded, twisted pair,
solid conductor wire. For nonplenum areas, use
Level IV 22 AWG (0.34 mm
solid conductor wire. For nonplenum areas, use
Level IV 22 AWG (0.34 mm
2
), such as U.S. part
AK3781 (one pair) or U.S. part AK3782 (two pair). In
plenum areas, use plenum-rated Level IV, 22 AWG
(0.34 mm
plenum areas, use plenum-rated Level IV, 22 AWG
(0.34 mm
2
) such as U.S. part AK3791 (one pair) or
U.S. part AK3792 (two pair). See Tables 9 and 11 for
part numbers. Contact Echelon Corp. Technical Sup-
port for the recommended vendors of Echelon
approved cables.
part numbers. Contact Echelon Corp. Technical Sup-
port for the recommended vendors of Echelon
approved cables.
•
Unswitched 24 Vac power wiring can be run in the
same conduit as the L
same conduit as the L
ON
W
ORKS
Bus cable.
•
Do not use different wire types or gauges on the
same L
same L
ON
W
ORKS
Bus segment. The step change in
line impedance characteristics causes unpredictable
reflections on the bus. When using different types is
unavoidable, use a Q7751A,B Router at the junction.
reflections on the bus. When using different types is
unavoidable, use a Q7751A,B Router at the junction.
•
In noisy (high EMI) environments, avoid wire runs
parallel to noisy power cables, or lines containing
lighting dimmer switches, and keep at least 3 in.
(76 mm) of separation between noisy lines and the
L
parallel to noisy power cables, or lines containing
lighting dimmer switches, and keep at least 3 in.
(76 mm) of separation between noisy lines and the
L
ON
W
ORKS
Bus cable.
•
Make sure that neither of the L
ON
W
ORKS
Bus wires
is grounded.
Power Wiring
A power budget must be calculated for each Excel 10 W7750
Controller to determine the required transformer size for
proper operation. A power budget is simply the summing of
the maximum power draw ratings (in VA) of all the devices to
be controlled by an Excel 10 W7750 Controller. This includes
the controller itself, the equipment actuators (ML6161, or
other motors) and various contactors and transducers, as
appropriate, for the Excel 10 configuration.
Controller to determine the required transformer size for
proper operation. A power budget is simply the summing of
the maximum power draw ratings (in VA) of all the devices to
be controlled by an Excel 10 W7750 Controller. This includes
the controller itself, the equipment actuators (ML6161, or
other motors) and various contactors and transducers, as
appropriate, for the Excel 10 configuration.
POWER BUDGET CALCULATION EXAMPLE
The following is an example power budget calculation for a
typical Excel 10 W7750B Controller.
typical Excel 10 W7750B Controller.
Assume a W7750 unit with a fan, two stages of D/X cooling,
modulating steam valve for heating, and modulating
economizer dampers. The power requirements are:
modulating steam valve for heating, and modulating
economizer dampers. The power requirements are:
DeviceVA
Information Obtained from
Excel 10 W7750B,C
12.0
W7750 Specification Data
Controller
ML6161
2.2
TRADELINE
Damper Actuator
Catalog
R8242A
21.0
TRADELINE
Contactor for fan
Catalog in-rush rating
D/X Stages
0.0
NOTE:
For this example, assume the cooling stage outputs
are wired into a compressor control circuit and,
therefore, have no impact on the power budget.)
are wired into a compressor control circuit and,
therefore, have no impact on the power budget.)
M6410A Steam
0.7
TRADELINE
Heating Coil Valve
Catalog, 0.32A at 24 Vac
TOTAL: 35.9
VA
The Excel 10 System example requires 35.9 VA of peak
power; therefore, a 40 VA AT72D Transformer is able to
provide ample power for this controller and its accessories.
Alternatively, a 75 VA AT88A Transformer could be used to
power two Excel 10 Systems of this type, or a 100 VA AT92A
Transformer could be used to power two of these Excel 10
Systems and meet NEC Class 2 restrictions (no greater than
100 VA). See Fig. 22 and 23 for illustrations of power wiring
details. See Table 8 for VA ratings of various devices.
power; therefore, a 40 VA AT72D Transformer is able to
provide ample power for this controller and its accessories.
Alternatively, a 75 VA AT88A Transformer could be used to
power two Excel 10 Systems of this type, or a 100 VA AT92A
Transformer could be used to power two of these Excel 10
Systems and meet NEC Class 2 restrictions (no greater than
100 VA). See Fig. 22 and 23 for illustrations of power wiring
details. See Table 8 for VA ratings of various devices.
EXCEL 10
VAV
VAV
EXCEL 10
VAV
VAV
EXCEL 10
VAV
VAV
EXCEL 10
Q7750A
ZONE
MANAGER
Q7750A
ZONE
MANAGER
TO C-BUS
(SEE FIG. 1)
(SEE FIG. 1)
L
ON
W
ORKS
BUS
SEGMENT NUMBER 2
L
ON
W
ORKS
BUS
SEGMENT NUMBER 1
L
ON
W
ORKS
BUS
SEGMENT NUMBER 2
T7770
L
ON
W
ORKS
BUS
ACCESS
ACCESS
Q7751A
FTT
L
FTT
L
ON
W
ORKS
BUS
ROUTER
ROUTER
209541B
TERMINATION
MODULE
TERMINATION
MODULE
209541B
TERMINATION
MODULE
TERMINATION
MODULE
M17497
EXCEL 10
CVAHU
EXCEL 10
CVAHU
EXCEL 10
CVAHU
EXCEL 10
CVAHU
EXCEL 10
CVAHU
T7560A,B