Bas/Ems Temperature Reset Option - York YCAL Series Installation Operation & Maintenance

SECTION 8 - UNIT OPERATION

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 clo-
sure input. The Remote Reset circuit board converts
the signals mentioned above into pulse width modu-
lated (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 sup-
plied by an Energy Management System. The Remote
Temp. Reset Board will convert 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 18 shows a diagram of the field
and factory electrical connections.
If a 0 - 10 VDC signal is available, it is applied to ter-
minals A+ and A-, and jumpers are applied to JU4
and JU2 on the reset board. This DC signal is condi-
tioned 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 chilled liquid setpoint for
values between 0VDC and 10VDC use the following
formula:
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 = 6VDC
(English)
°Reset = 6VDC x 20°F = 12°F Reset
10
New Setpoint = 45°F + 12°F = 57°F
(Metric)
°Reset = 6VDC x 11. 11°C = 6.67°C Reset
10
New Setpoint = 7.22°C + 6.67°C = 13.89°C
* Max Reset Value is the "Max EMS-PWM Remote Temp. Reset" setpoint
value described in the program ming section under Cooling Setpoints.
Programmable values are from 2°F to 40°F (1.11°C to 11.11°C).
142
10
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
CTB1 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)
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
16
Setpoint = 45°F + 5°F = 50°F
(Metric)
°Reset = 8mA x 5.56°C = 2.78°C Reset
16
Setpoint = 7.22°C + 2.78°C = 10.0°C
A 240­24 Volt Ratio Transformer (T3)
is used to derive nominal 12 volt output
from the 120 volt supply.
If the Contact Closure input is used. The connec tions
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 CTB1 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
measured at TP3 to terminal 10 on the circuit board.
The reset value will be the "Max EMS-PWM Re-
mote Temp. Reset" setpoint value pro grammed 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
PN 031­00808­000 suppres sor.
FORM 150.66-NM3
ISSUE DATE: 09/25/2020
16
JOHNSON CONTROLS