Technical Bulletin—TC-9102 11
The PAT output is a pair of triacs which are switched on to open and
close an incrementally driven heating or cooling valve. The duration of
switching is directly proportional to the change in the controller output
and related to the full stroke time of the valve such that a 100% change
will completely open or close the valve. At the 0% or 100% position the
duration of switching is increased to ensure that the valve is completely at
its end position and the appropriate triac is switched on for the full stroke
time every two hours to ensure that the valve remains at its end position.
To prevent unnecessary wear on the actuator, the triac output will only be
switched when the output change exceeds 1% in the same direction as the
previous change or 2% if the direction of change is reversed. The default
full stroke time is 60 seconds.
100
0
5
10 30
Output (%)
Room
Temperature (°C)
Heating
Cooling
12 14 16 18 20 22 24 26
Night
Standby
Comfort
Comfort
Standby
Night
Low Limit
tc2hcvdc
Figure 8: Heating/Cooling Control 0-10 VDC, DAT, PAT
The output is a pair of triacs which are switched on in sequence as the
controller output increases. The first stage triac is switched as soon as the
output is above 0% and the second stage triac is switched when the output
is equal to the set load rating for the first stage which is defaulted to 50%.
The switching differential is fixed at 5%. When this type of output is used
with 3-speed fan control, the output will be switched off whenever the
fan speed is manually overridden to the “OFF” position on the Room
Control Module. The control diagram is shown below.
Night
Standby
0
Room
Temperature
°C
Heating
Coolin
100
Output (%)
1
222 222
1
1
111
Comfort
Comfort
Standby
Night
Low Limit
5
10
30
12 14 16 18 20 22 24 26
Figure 9: Heating/Cooling Control - 2-Stage On/Off
PAT - Position
Adjust Type
2-Stage On/Off
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