York MILLENNIUM YCUL0016SC, Assembly, Installation, Operation & Maintenance

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YORK INTERNATIONAL
128
EMS-PWM REMOTE TEMPERATURE RESET
EMS-PWM Remote Temperature Reset is a value that
resets the Discharge Air Temperature Setpoint based
on a PWM input (timed contact closure) to the
microboard. This PWM input would typically be sup-
plied by an Energy Management System.
A contact closure on the PWM Temp Reset input at
CTB 1 terminals 13 - 20, will reset the Discharged Air
Temperature setpoint based on the length of time the
contacts remain closed. The maximum temperature re-
set is achieved at a contact closure of 11 seconds. This
is the longest contact closure time allowed. One sec-
ond is the shortest time allowed and causes the Dis-
charge Air Temperature Setpoint to revert back to the
Local programmed value. The reset value is always
added to the Setpoint, meaning that this function never
lowers the Discharge Air Temperature below the lo-
cally programmed value, it can only reset to a higher
value. The microboard must be refreshed between 30
seconds and 30 minutes. Any contact closure occur-
ring sooner than 30 seconds will be ignored. If more
than 30 minutes elapse before the next contact closure,
the setpoint will revert back to the locally programmed
value. The new Discharge Air Temperature setpoint is
calculated by the following equations:
Setpoint =
Local Discharge Air Temperature Se °rRset
°Reset =
(Contact Closure - 1) x (*Max. Reset Value)
10
Example:
Local Setpoint = 55°F (12.8°C)
*Max Reset Value = 10°F (5.6°C)
Contact Closure Time = 6 Seconds.
(English)
(6 sec. - 1) 10°F/10) = 5°F Reset
So...the new setpoint = 55°F + 5°F = 60°F. This can be
viewed by pressing the Cooling Setpoints key twice.
The new value will be displayed as “REM SETP =
60.0°F.”
(Metric)
(6 sec - 1) * (5.6°C/10) = 2.8°C
Reset Cooling Setpoint = 12.8°C + 2.8°C = 15.6°C
So...the new reset Cooling Setpoint = 12.8 °C + 2.8 °C
= 15.6 °C. This can be viewed by pressing the Cooling
Setpoints key twice. The new value will be displayed
as “REM SETP = 15.6 °C.”
BAS/EMS TEMPERATURE RESET OPTION
The Remote Reset Option allows the Control Center of
the unit to reset the discharge air temperature setpoint
using a 0 - 10 VDC input, a 4 - 20 mA input, or a con-
tact closure input. The Temperature Reset circuit board
converts the signals mentioned above into pulse width
modulated (PWM) signals which the microprocessor
can use. 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 =
XX.X°F”
The reset option would be used when reset of the dis-
charge air temperature setpoint is required and a PWM
signal (timed contact closure) cannot be supplied by an
Energy Management System. The reset board will con-
vert a voltage, current, or contact signal that is avail-
able from an EMS to a PWM signal, and every 80 sec-
onds provide a PWM input to the microboard. Figure
12 shows a diagram of the field and factory electrical
connections.
If a 0 - 10 VDC signal is available, it is applied to ter-
minals A+ and A-, and jumpers are applied to JU4
and JU2 on the reset board. This DC signal is condi-
tioned to a 1 - 11 second PWM output and supplied to
the PWM input on the microboard at CTB1 terminals
13 - 20. To calculate the reset discharge air tempera-
ture setpoint for values between 0 VDC and 10 VDC,
use the following formula:
setpoint = discharge air temperature se °reset
°reset = (DC voltage signal) x (*Max Reset Value)
10
Example:
Local Disch. Air Temp. Setpoint = 55°F (12.8°C)
*Max Reset Value = 20°F (11.1°C)
Input Signal = 6 VDC
(English)
°reset =
6 VDC x 20°F
= 12°F reset
10
Setpoint = 55°F + 12 °F = 67°F
Unit Controls
Please note that temperature reset is
only usable with the control mode set
to discharge air temperature. It is not
available with the control mode pro-
grammed for suction pressure control.