EXCEL 10 W7750A,B,C CONSTANT VOLUME AHU CONTROLLER
74-2958—132
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 wirin
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.
• 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
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
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.
• Unswitched 24 Vac power wiring can be run in the
same conduit as the L
ON
W
ORKS
Bus cable.
• Do not use different wire types or gauges on the
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.
• 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
ON
W
ORKS
Bus cable.
• Make sure that neither of the L
ON
W
ORKS
Bus wires
is grounded.
Power Wiring
A power bud
et must be calculated for each Excel 10 W7750
Controller to determine the re
uired transformer size for
proper operation. A power bud
et is simpl
the summin
of
the maximum power draw ratin
s
in VA
of all the devices to
be controlled b
an Excel 10 W7750 Controller. This includes
the controller itself, the e
uipment actuators
ML6161, or
other motors
and various contactors and transducers, as
appropriate, for the Excel 10 confi
uration.
POWER BUDGET CALCULATION EXAMPLE
The followin
is an example power bud
et calculation for a
t
pical Excel 10 W7750B Controller.
Assume a W7750 unit with a fan, two sta
es of D/X coolin
,
modulatin
steam valve for heatin
, and modulatin
economizer dampers. The power re
uirements are:
DeviceVA Information Obtained from
Excel 10 W7750B,C 12.0 W7750 Specification Data
Controller
ML6161 2.2 TRADELINE
Damper Actuator Catalo
R8242A 21.0 TRADELINE
Contactor for fan Catalo
in-rush ratin
D/X Sta
es 0.0
NOTE: For this example, assume the coolin
sta
e outputs
are wired into a compressor control circuit and,
therefore, have no impact on the power bud
et.
M6410A Steam 0.7 TRADELINE
Heatin
Coil Valve Catalo
, 0.32A at 24 Vac
TOTAL: 35.9 VA
The Excel 10 S
stem example re
uires 35.9 VA of peak
power; therefore, a 40 VA AT72D Transformer is able to
provide ample power for this controller and its accessories.
Alternativel
, a 75 VA AT88A Transformer could be used to
power two Excel 10 S
stems of this t
pe, or a 100 VA AT92A
Transformer could be used to power two of these Excel 10
S
stems and meet NEC Class 2 restrictions
no
reater than
100 VA
. See Fi
. 22 and 23 for illustrations of power wirin
details. See Table 8 for VA ratin
s of various devices.
EXCEL 10
VAV
EXCEL 10
VAV
EXCEL 10
VAV
EXCEL 10
Q7750A
ZONE
MANAGER
TO C-BUS
(SEE FIG. 1)
L
ONWORKS BUS
SEGMENT NUMBER 2
L
ONWORKS BUS
SEGMENT NUMBER 1
L
ONWORKS BUS
SEGMENT NUMBER 2
T7770
L
ONWORKS
BUS
ACCESS
Q7751A
FTT
L
ONWORKS
BUS
ROUTER
209541B
TERMINATION
MODULE
209541B
TERMINATION
MODULE
EXCEL 10
CVAHU
EXCEL 10
CVAHU
EXCEL 10
CVAHU
EXCEL 10
CVAHU
EXCEL 10
CVAHU
T7560A,B
