37
4-20 mA TEMPERATURE RESET — The control system is
also capable of temperature reset based on an externally pow-
ered 4 to 20 mA signal. The Energy Management Module
(EMM) is required for temperature reset using a 4 to 20 mA
signal.
To use 4-20 mA Temperature Reset, four variables must be
configured: Cooling Reset Select, Current No Reset Value
(milliamp signal at which no temperature reset is required),
Current Full Reset Value (milliamp signal at which full tem-
perature reset is required), and Cooling Reset Deg Value (the
maximum amount of temperature reset desired).
To configure this option with the Touch Pilot™ display:
In the example in Fig. 34, at 4 mA no reset takes place and
at 20 mA, 5° F (2.8° C) chilled water set point reset is required.
CAUTION
Care should be taken when interfacing with other control
systems due to possible power supply differences such as a
full wave bridge versus a half wave rectification. Connec-
tion of control devices with different power supplies may
result in permanent damage. Touch Pilot controls incorpo-
rate power supplies with half wave rectification. A signal
isolation device should be utilized if the signal generator
incorporates a full wave bridge rectifier.
DISPLAY NAME PATH VALUE
Cooling Reset
Select
0=None, 1=OAT
2=Delta T,
3=4-20mA control
4=Space Temp
Main Menu
Configuration Menu
Reset Configuration
Low = 0° F (0° C)
Default = 0° F (0° C)
High = 4 F (2.2 C)
Current No
Reset Value
Low = 0° F (0° C)
Default = 0° F (0° C))
High = 20 F (11.1 C)
Current Full
Reset Value
Low = 0° F (0° C)
Default = 0° F (0° C)
High = 20 F (11.1 C)
Cooling Reset
Deg Value
Low = 30 F (16.7 C)
Default = 0° F (0° C)
High = 30 F (16.6 C)
0
1
2
3
4
5
6
0101420
mA Signal
Degrees Reset (deg F)
2
Cooling Reset
Deg. Value
(cr_deg)
Current No Reset Value
(v_hr_no)
Current Full Reset Value
(v_hr_fu)
46 8
12 16 18
a30-5885
Fig. 34 — Example: 4 to 20 mA Temperature Reset
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