Watlow QPAC - Manual (Page 20)

20 QPAC User's Guide Chapter 2: Install & Wire
QPAC system Wiring Example
The most common failure mode of an SCR is in the shorted state. If this hap-
pens, the temperature control can no longer control the SCR and a run-away
condition exists. An independent high limit control must be used that will
sense unsafe temperature and disengage the circuit breaker via undervolt-
age trip or a mechanical contactor as shown below.
System Wiring
QPAC System Wiring
Example, Overtemperature
Cutout.
∫
WARNING:
Follow National
Electric Code safety
practices and other lo-
cally applicable codes to
avoid potential electric
shock when wiring this
unit to a power source,
and to electrical sensors
or peripheral devices.
Failure to do so could
result in serious injury or
death.
PM6C2FA - ALAJAAA
98
99
CC
CA
CB
B5
D6
D5 F1
G1
H1
T1
S1
R1
L4
K4
T2
S2
R2
RY1
L1
N
Q32-202-300-BV0
4
5
+
-
-
+
L3
L2
T1 L1 L2 L3 T3
Limit
Thermocouple
Controller
Thermocouple
1A
1A
2ASB
2ASB
208/120V
Fan Assembly