York YLUA0078 - BAS;EMS DISCHARGE AIR TEMPERATURE RESET USING A VOLTAGE OR CURRENT SIGNAL

JOHNSON CONTROLS
140
FORM 150.73-NM1
ISSUE DATE: 09/04/2020
SECTION 8 – UNIT OPERATION
BAS/EMS DISCHARGE AIR TEMPERATURE
RESET USING A VOLTAGE OR CURRENT
SIGNAL
The Remote Reset Option allows the Control Center
of the unit to reset the discharge air temperature set-
point using a 0 VDC to 10 VDC input, or a 4 mA to
20 mA input connected to XTBC1 terminals A- and
A+. Whenever a reset is called for, the change may be
noted by pressing the Cooling Setpoints key twice. The
new value will be displayed as “REM SETP = XXX
°F.”
If a 0 VDC to 10 VDC signal is supplied, it is applied to
terminals A+ and A-, and jumper JP1 on the I/O board
must be inserted between pins 2 and 3. To calculate
the reset discharge air temp setpoint for values between
0 VDC and 10 VDC, use the following formula:
Setpoint = Local Discharge Air Temp Setpoint +
°Reset
°Reset = (DC voltage signal) x (*Max Reset Value)
10
Example:
Local Discharge Air Temp Setpoint = 45 °F (7.22 °C)
*Max Reset Value = 20 °F (11.11 °C)
Input Signal = 6 VDC
(English)
°Reset = 6 VDC x 20 °F = 12 °F Reset
10
New Setpoint = 45 °F + 12 °F = 57 °F
(Metric)
°Reset = 6 VDC x 11. 11 °C = 6.67 °C Reset
10
New Setpoint = 7.22 °C + 6.67 °C = 13.89 °C
* Max Reset Value is the “Max EMS-PWM Remote Temp. Reset”
setpoint value described in the programming section under Cool-
ing Setpoints. Programmable values are from 2 °F to 40 °F (1.11
°C to 11.11 °C).
** Note: The Suction Pressure Setpoints are not remotely
resettable.
If a 4 mA to 20 mA signal is supplied, it is applied to
terminals A+ and A- and jumper JP1 on the I/O board
must be installed between pin 1 and 2. To calculate the
discharge air temp setpoint for values between 4 mA
and 20 mA use the following formula:
Setpoint = Local Discharge Air Temp Setpoint +
°Reset
°Reset = (mA signal - 4) x (*Max Reset Value)
16
Example:
Local Discharge Air Temp Setpoint = 45° (7.22 °C)
*Max Reset Value = 10 °F (5.56 °C)
Input Signal = 12 mA
(English)
°Reset = 8 mA x 10 °F = 5 °F Reset
16
Setpoint = 45 °F + 5 °F = 50 °F
(Metric)
°Reset = 8 mA x 5.56 °C = 2.78 °C Reset
16
Setpoint = 7.22 °C + 2.78 °C = 10.0 °C
A 240-24 Volt Ratio Transformer (T3) is
used to derive nominal 12 V output from
the 120 V supply.