Honeywell W7761A - Manual (Page 23)

EXCEL 10 W7761A INPUT/OUTPUT DEVICE
23 74-2699
M10090
24 VAC 120/240 VAC
TRANSFORMER
EARTH`
GROUND
24 25
1
EARTH`
GROUND
24 25
1
EARTH`
GROUND
24 25
1
W7761A W7761A W7761A
Fig. 13. Power wiring details for two or more Excel 10s per transformer.
IMPORTANT
If the W7761A Device is used on Heating and Cooling Equipment (UL 1995 US only) devices and the transformer
primary power is more than 150 volts, connect the transformer secondary to earth ground, see Fig. 14.
M10088
24 VAC
LINE VOLTAGE`
GREATER`
THAN 150 VAC
TRANSFORMER
EARTH`
GROUND
EARTH`
GROUND
1` IF THE W7761 CONTROLLER IS USED IN UL 1995 EQUIPMENT AND `
THE PRIMARY POWER IS MORE THAN 150 VOLTS, GROUND ONE `
SIDE OF TRANSFORMER SECONDARY.
1
1
W7761A
Fig. 14. Transformer power wiring details for one Excel 10 used in UL 1995 equipment (U.S. only).
IMPORTANT
Notes on power wiring:
•
All field wiring must conform to local codes and ordinances.
•
To maintain NEC Class 2 and UL ratings, the installation must use transformers of 100 VA or less capacity.
•
For multiple controllers operating from a single transformer, the same side of the transformer secondary must be
connected to the same input terminal in each device and the ground terminals (1 on the W7761A) must be
connected to a verified earth ground for each device in the group. See Fig. 13. (Device configurations are not
necessarily limited to three devices per transformer.)
•
For the W7761A Device (which has Triac outputs), all output devices must be powered from the same transformer
as the one powering the Excel 10 W7761A Device.
•
Use the heaviest gauge wire available, up to 14 AWG (2.0 mm 2 ) with a minimum of 18 AWG (1.0 mm 2 ) for all
power and earth ground connections.
• To minimize EMI noise, do not run Triac output wires in the same conduit as the input wires or the E-Bus
communications loop.
•
Unswitched 24 Vac power wiring can be run in the same conduit as the E-Bus cable.