Johnson Controls System 450 Series Technical Bulletin

Table 6: Control and expansion modules with relay output
Callout Description
1 Internal SPDT dry-contact relay; shown in the normally closed position
2 6 Pin module connector
3 Low-voltage (< 30 V) terminal block for optional 24 V supply power to the control system, input temperature
sensor terminals, Sn-1 and Sn-2, and pressure sensor terminal, Sn-3.
Note: The low-voltage terminal block is on C450 control modules only. C450 expansion modules do not
have low-voltage terminal blocks.
4 C terminals are connected internally as the low-voltage common for the sensors
5 C450CCU features one or two relays as follows:
• C450SBN-4C expansion module: one relay
• C450SCN-4C expansion module: two relays
6 Line-voltage terminals for SPDT output relay
Note: The relay output terminals connect to an internal SPDT dry-contact relay and do not
supply power to the application.
The following table provides information about System 450 control, expansion, and power module
terminal blocks, terminal labels, function, and wire size requirements.
Table 7: System 450 wiring terminals and wire sizes
Terminal block type Terminal label Terminal function Wire sizes
24 V Provides a power terminal to connect a
24 VAC input when you do not use the
C450YNN module.
COM Provides a 24 VAC COM terminal to connect
a 24 VAC COM input when you do not use a
C450YNN module.
This terminal is isolated from the C terminal
by a common mode choke internal to the
control.
5 V Provides 5 VDC power for a P499 or P599
transducer.
Sn-1 Connect to an A99 temperature sensor only.
Sn-2 Connect to an A99 temperature sensor or
binary switch input.
Sn-3 Connect to a P499 or P599 pressure
transducer.
Sensor and low-voltage
supply power terminal
block
C450CCU control
module
C Provides low-voltage common connections
for passive or active sensors connected to
Sn-1, Sn-2, or Sn-3.
The common terminals are connected
together internally.
0.08 mm
2
to 1.50 mm
2
28 AWG to 16 AWG
System 450 Series C450CCU Condensing Unit Control System Technical Bulletin22

Johnson Controls System 450 Series Specifications

General

Brand	Johnson Controls
Model	System 450 Series
Category	Control Unit
Language	English