SYLK™ I/O DEVICES
31-00028—02 4
IMPORTANT
• If a controller is used on Heating and Cooling
Equipment (UL 1995, U.S. only) and transformer
primary power is more than 150 volts, connect the
transformer secondary common to earth ground
(see Fig. 5 on page 6).
• When multiple controllers operate from a single
transformer, connect the same side of the trans-
former secondary to the same power input termi-
nal in each device. The earth ground terminal
(terminal 3) must be connected to a verified earth
ground for each controller in the group (see Fig. 6
on page 7).
POWER BUDGET CALCULATION EXAMPLE
Table 3 is an example of a power budget calculation for
typical Spyder LON controller and Sylk IO devices. While
the example is shown for only these models, the process is
applicable for all controller and device configurations.
Table 3. Power budget calculation example.
a
Excludes the use of digital Triac outputs.
The system example above requires 31.7 VA of peak power.
Therefore, a 100 VA AT92A transformer could be used to
power one controller and device of this type. Because the
total peak power is less than 33 VA, this same transformer
could be used to power this configuration and meet NEC
Class 2 restrictions (no greater than 100 VA).
See Fig. 4–Fig. 6 beginning on page 6 for illustrations of
controller power wiring. See Table 4 for VA ratings of
various devices.
Table 4. VA ratings for transformer sizing.
a
When used, each digital Triac output can add an addi-
tional 22 VA (peak) and 12 VA long-term.
For contactors and similar devices, the in-rush power ratings
should be used as the worst case values when performing
power budget calculations. Also, the application engineer
must consider the possible combinations of simultaneously
energized outputs and calculate the VA ratings accordingly.
The worst case, which uses the largest possible VA load,
should be determined when sizing the transformer.
Each device requires 24 Vac power from an energy-limited
Class II power source. To conform to Class II restrictions
(U.S. only), transformers must not be larger than 100 VA. A
single transformer can power more than one device.
GUIDELINES FOR POWER WIRING ARE AS FOLLOWS:
— For multiple devices operating from a single trans-
former, the same side of the transformer secondary
must be connected to the same power input termi-
nal in each device. The earth ground terminal must
be connected to a verified earth ground for each
device in the group (see Fig. 6 on page 7). Device
configurations are not necessarily limited to three
devices, but the total power draw, including acces-
sories, cannot exceed 100 VA when powered by the
same transformer (U.S. only).
— See Fig. 5 on page 6 for device power wiring used in
UL 1995 equipment (U.S. only).
— Many devices require all loads to be powered by the
same transformer that powers the device.
— Keep the earth ground connection wire run as short
as possible (refer to Fig. 4–Fig. 6 beginning on
page 6).
— Do not connect earth ground to the device’s digital
or analog ground terminals (refer to Fig. 4 and
Fig. 6).
— Unswitched 24 Vac power wiring can be run in the
same conduit as the L
ONWORKS® Bus cable.
Device
VA
Informatio
nObtained From
PUL6438SR 5.0 Spyder LON Product Data
Sheet
SIO6042
5.0
a
See “Specifications” on
page 2.
R8242A
Contactor fan
rating
21.0
TRADELINE
®
Catalog
inrush rating
D/X Stages 0.0 For example, assume
cooling stage outputs are
wired into a compressor
control circuit and have
no impact on the budget.
M6410A Steam
Heating Coil
Valve
0.7
TRADELINE
®
Catalog,
0.32A 24 Vac
TOTAL 31.7
Device Description VA
PVL0000AS,
PVL4022AS, and
PVL6436AS
controllers and
Series 60 Floating
Damper Actuator
Controller and Actuator
a
9.0
PUL1012S,
PUL4024S,
PUL6438S,
PVL4024NS, or
PVL6438NS
Controller
a
5.0
SIO12000
IO Device
a
3.0
SIO4022 4.0
SIO642 5.0
ML684 Versadrive Valve Actuator 12.0
ML6161 Damper Actuator, 35 lb-in. 2.2
ML6185
Damper Actuator SR 50 lb-in
12.0
ML6464 Damper Actuator, 66 lb-in. 3.0
ML6474 Damper Actuator, 132 lb-in. 3.0
R6410A Valve Actuator 0.7
R8242A Contactor 21.0
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