York YLAA0115 - Remote BAS;EMS Temperature Reset Using a Voltage or Current Signal

JOHNSON CONTROLS
159
SECTION 8 – UNIT OPERATION
FORM 150.72-ICOM6
ISSUE DATE: 12/29/2017
8
REMOTE BAS/EMS TEMPERATURE RESET
USING A VOLTAGE OR CURRENT SIGNAL
The Remote Reset Option allows the Control Center
of the unit to reset the chilled liquid setpoint using a
0 to 10VDC input, or a 4 to 20mA 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 to 10VDC signal is supplied, it is applied to Ter-
minals A+ and A-, and jumper JP1 on the I/O board
must be inserted between pins 2 and 3. To calculate the
reset chilled liquid setpoint for values between 0VDC
and 10VDC use the following formula:
Setpoint = Local Chilled Liquid Setpoint + °Reset
°Reset = (DC voltage signal) x (*Max Reset Value)
10
Example:
Local Chilled Liquid Setpoint = 45 °F (7.22 °C)
*Max Reset Value = 20 °F (11.11 °C)
Input Signal = 6VDC
(English)
°Reset = 6VDC x 20 °F
10
New Setpoint = 45 °F + 12 °F = 57 °F
(Metric)
°Reset = 6VDC x 11. 11 °C
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 Remote Setpoint Control on page
125 under “Cooling Setpoints”. Programmable values are from 2
°F to 40 °F (1.11 °C to 11.11 °C).
= 12 °F Reset
= 6.67 °C Reset
If a 4 to 20mA signal is supplied, it is applied to Ter-
minals A+ and A- and jumper JP1 on the I/O board
must be installed between pin 1 and 2. To calculate the
chilled liquid setpoint for values between 4mA and 20
mA use the following formula:
Setpoint = Local Chilled Liquid Setpoint + °Reset
°Reset = (mA signal - 4) x (*Max Reset Value)
16
Example:
Local Chilled Liquid Setpoint = 45° (7.22 °C)
*Max Reset Value = 10 °F (5.56 °C)
Input Signal = 12 mA
(English)
°Reset = 8mA x 10 °F
16
Setpoint = 45 °F + 5 °F = 50 °F
(Metric)
°Reset = 8mA x 5.56 °C
16
Setpoint = 7.22 °C + 2.78 °C = 10.0 °C
= 5 °F Reset
= 2.78 °C Reset
A 240 to 24 Volt Ratio Transformer (T3)
is used to derive nominal 12 volt output
from the 120 volt supply.