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Unit Controls
FIG. 7 – FIELD AND FACTORY ELECTRICAL CONNECTIONS
OPTIONAL REMOTE TEMPERATURE RESET BOARD
If a 4 - 20 ma 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 4 ma 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 = 8 ma x 10°F = 5°F reset
16
setpoint = 45°F + 5°F = 50°F
The 208/240V primary is correct, even
though 120VAC is applied to it. The
transformer will "step-down" the 120VAC,
to 12VAC which is needed for the BAS
Option.
*
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).
88
(Metric)
°reset = 8 ma x 5.56°C = 2.78°C reset
16
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 10 VDC 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.
The coil of any added relay used for re-
set must be suppressed to prevent pos-
sible component damage. Use YORK
PN031-00808-000 suppressor.
035-15961-000
LD03875
YORK INTERNATIONAL
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