York MILLENNIUM YCAL0043SC Manual page 87

EMS-PWM REMOTE TEMPERATURE RESET
EMS-PWM Remote Temperature Reset is a value that
resets the Chilled Liquid Setpoint based on a PWM in-
put (timed contact closure) to the microboard. This PWM
input would typically be supplied by an Energy Manage-
ment System.
A contact closure on the PWM Temp Reset input at CTB
1 terminals 13 - 20, will reset the chilled liquid setpoint
based on the length of time the contacts remain closed.
The maximum temperature reset is achieved at a con-
tact closure of 11 seconds. This is the longest contact
closure time allowed. One second is the shortest time
allowed and causes the Chilled Liquid Setpoint to revert
back to the Local programmed value. The reset value is
always added to the Chilled Liquid Setpoint, meaning
that this function never lowers the Chilled Liquid Setpoint
below the locally programmed value, it can only reset to
a higher value. The microboard must be refreshed be-
tween 30 seconds 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 chilled liquid setpoint is calculated by
the following equations:
setpoint = local chilled liquid setpoint + °reset
°reset = (Contact Closure - 1) x (*Max. Reset Value)
Example:
Local Chilled Liquid Setpoint = 45°F (7.22°C).
*Max Reset Value = 10°F (5.56°C)
Contact Closure Time = 6 Seconds.
(English)
(6 sec. - 1) (10°F/10) = 5°F Reset
So...the new chilled liquid setpoint = 45°F + 5°F= 50°F.
This can be viewed by pressing the Cooling Setpoints
key twice. The new value will be displayed as "REM
SETP = 50.0°F."
(Metric)
(6 sec - 1) * (5.56°C/10) = 2.78°C
Reset Cooling Setpoint = 7.22°C + 2.78°C = 10.0°C
So...the new reset Cooling Setpoint = 7.22 °C + 2.78°C
= 10°C. This can be viewed by pressing the Cooling
Setpoints key twice. The new value will be displayed as
"REM SETP = 10.0°C."
* Max Reset Value is the "Max EMS-PWM Remote Temp. Reset" setpoint value described in the programming section under Cooling
Setpoints. Programmable values are from 2°F to 40°F (1.11°C to 22.22°C).
YORK INTERNATIONAL
BAS/EMS TEMPERATURE RESET OPTION
The Remote Reset Option allows the Control Center of
the unit to reset the chilled liquid setpoint using a 0 - 10
VDC input, a 4 - 20 ma input, or a contact closure input.
The Remote Reset circuit board converts the signals
mentioned above into pulse width modulated (PWM)
signals which the microprocessor can understand.
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"
The optional Remote Reset option would be used when
reset of the chilled liquid setpoint is required and a PWM
signal (timed contact closure) cannot be supplied by an
Energy Management System. The Remote Temp. Re-
set Board will convert a voltage, current, or contact sig-
nal that is available from an EMS to a PWM signal, and
every 80 seconds provide a PWM input to the microboard.
Figure 3 shows a diagram of the field and factory elec-
trical 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 CTB 1 terminals 13 - 20. To
calculate the reset chilled liquid setpoint for values be-
tween 0 VDC and 10 VDC use the following formula:
10
setpoint = local chilled liquid setpoint + °reset
°reset = (dc voltage signal) x (*Max Reset Value)
Example:
Local Chilled Liquid 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
setpoint = 45 °F + 12 °F = 57°F
(Metric)
°reset = 6 VDC x 11. 11°C = 6.67°C reset
setpoint = 7.22°C + 6.67°C = 13.89°C
FORM 150.62-NM2
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