Johnson Controls METASYS VAV110 Technical Manual page 29

Power
Transformer
Isolation
VAV110/111 and
VAV140/141
Load Isolation
VAV110/111 and
VAV140/141
I/O and
3 9 F 4 0 F 4 1 F
Communication
Terminals
L
Power
Transformer
N
See CAUTION below
To
Load
Contactor
Figure 9: Transformer Wiring Diagram for
Series 110/111 VAV Controllers
!
CAUTION: Some local electric codes require the secondary
common of stepdown transformers be connected to
earth ground (typically on units powered by more than
150 VAC). You may have a maximum of one single
earth ground connection, which must be at the
transformer secondary common, whether one or
multiple controllers are powered by the same
transformer
You may connect the Series VAV110/111 and VAV140/141 power
transformer secondary directly to earth ground. If you elect to do so, the
grounded side must connect to the Common power input terminal of the
controller. You do not need a separate isolation transformer for these
controllers.
If VAV output loads such as contactor or solenoid coils are grounded, you
must use a separate isolation relay for each load.
The VAV terminal designations, which identify sensor, actuator, and power
connection points, are illustrated in Figures 10 through 12 and Tables 6
through 8. Use the HVAC PRO for Windows Configuration Tool to assign
the inputs and outputs for a specific application. The filename.PRN file
identifies these connections after you assemble the configuration.
You may make connections to the VAV by connecting single wires to the
individual screw or spade terminals.
24VAC
COM
ZBUS
REF
N2-
N2+
VAV Controller—Variable Air Volume (VAV) Controller 29
+15VDC +15VDC
24VAC
COM
ZBUS
REF
N2-
BO1
N2+
24VAC
24VAC
TRIACS
COMMON
COMMON
COMMON
COMMON
COMMON
transeri