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YORK INTERNATIONAL
94
FIG. 7 – FIELD AND FACTORY ELECTRICAL CONNECTIONS
OPTIONAL REMOTE TEMPERATURE RESET BOARD
If a 4-20mA signal is available, it is applied to termi-
nals A+ and A- and jumpers are applied to JU5 and
JU3 on the reset board. The mA signal is conditioned to
a 1-11 second PWM output. The PWM output is then
supplied to the PWM input on the microboard at CTB 1
terminals 13 - 20. 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 = 5°F reset
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setpoint = 45°F + 5°F = 50°F
(Metric)
°reset = 8mA x 5.56°C = 2.78°C reset
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setpoint = 7.22°C + 2.78°C = 10.0°C
If the Contact Closure input is used. The connections
are made to terminals C and D and only jumper JUI
must be in place on the reset board. This input is used
when a
single
reset value is needed. When the contacts
are closed, the remote temperature reset board will con-
vert this contact closure to a PWM signal that is applied
to CTB 1 terminals 13 - 20.
To set the PWM output, the contacts must be closed on
inputs C - D, and potentiometer R11 (located on the front
edge of the PC board) is adjusted to 10VDC as mea-
sured at TP3 to terminal 10 on the circuit board. The
reset value will be the “Max EMS-PWM Remote Temp.
Reset” setpoint value programmed in the SETPOINTS
section under the Cooling Setpoints key.
NOTE: The coil of any added relay used for reset must
be suppressed to prevent possible component
damage. Use YORK PN031-00808-000
suppressor.
LD03875
035-15961-000
035-15961-000
+
–
Unit Controls
A 240-24 Volt Ratio Transformer (T3)
is used to derive nominal 12 volt out-
put from the 120 volt supply.
* 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 11.11°C).