Download York ZR300 Specifications

UNIT CONTROLS
FIG. 3 - FIELD AND FACTORY ELECTRICAL CONNECTIONS OPTIONAL REMOTE TEMPERATURE RESET
BOARD
If a 4 - 20 ma signal is available, it is applied to
terminals A+ and A- and jumpers are applied 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 value between 4 ma and
20 ma use the following formula:
setpoint = local chilled liquid setpoint = °reset
°reset = (ma signal - 4) x (*Max reset Value)
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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
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A 240-24 Volt Ratio Transformer (T3) is
used to derive nominal 12 volt output
from the 120 volt supply.
NOTE
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 convert 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 measured 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.
setpoint = 45°F + 5°F = 50°F
(Metric)
°reset = 8 ma x 5.56°C = 2.78°C reset
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NOTE:
The coil of any added relay used for reset must be
suppressed to prevent possible component damage.
Use YORK PN031-00808-00 suppressor.
setpoint = 7.22°C + 2.78°C = 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 11.11°C).
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