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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
second is the shortest time allowed and causes the
Discharge 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 locally
programmed value, it can only reset to a higher value.
The microboard must be refreshed between 30 sec-
onds and 30 minutes. Any contact closure occurring
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 calcu-
lated by the following equations:
Setpoint =
Local Discharge Air Temperature setpoint + °reset
° Reset =
(Contact Closure - 1) x
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) x (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) x (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."
Please note that temperature reset is only
usable with the Control Mode set to Dis-
charge Air Temperature. It is not avail-
able with the Control Mode programmed
for Suction Pressure Control.
YORK INTERNATIONAL
(*Max. Reset Value)
10
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 contact
closure input. The Temperature Reset circuit board con-
verts the signals mentioned above into pulse width modu-
lated (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 available
from an EMS to a PWM signal, and every 80 seconds
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 termi-
nals A+ and A-, and jumpers are applied to JU4 and
JU2 on the reset board. This DC signal is conditioned 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 temperature setpoint
for values between 0 VDC and 10 VDC, use the following
formula:
Setpoint =
discharge air temperature setpoint + °reset
° Reset =
(DC voltage signal) x (*Max Reset Value)
10
Example:
Local Discharge Air Temp. Setpoint = 55°F (12.8°C)
*Max Reset Value = 20°F (11.1°C)
Input Signal = 6 VDC
(English)
6 VDC x 20°F
°reset =
10
setpoint = 55°F + 12 °F = 67°F
(Metric)
6 VDC x 11. 1°C
°reset =
10
setpoint = 12.8°C + 6.6°C = 19.4°C
*
Max Reset Value is the "Max EMS-PWM Remote Temp. Reset"
setpoint values described in the programming section under
Cooling Setpoints. Programmable values are from 2°F to 40°F
(1.1°C to 22.2°C.)
FORM 150.63-NM2
= 12°F reset
= 6.6°C reset
127
3
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