Compressor Run Status; Alarm Status; Ems-Pwm Remote Temperature Reset; Table 25 - Compressor Operation - Load Limiting - York YCAL Series Installation Operation & Maintenance

FORM 150.66-NM3
ISSUE DATE: 09/25/2020
TABLE 25 – COMPRESSOR OPERATION – LOAD
LIMITING
COMPRESSORS
IN UNIT
2
3
4
5
6
Simultaneous operation of Remote
Load Limiting and EMS­PWM Tem-
perature Reset (described on following
pages) cannot occur.

COMPRESSOR RUN STATUS

Compressor run status is indicated by closure of con-
tacts at TB1 – terminals 25 to 26 for system 1 and TB1
– terminals 27 to 28 for system 2.

ALARM STATUS

System or unit shutdown is indicated by normally-
open alarm contacts opening whenever the unit shuts
down on a unit fault, locks out on a system fault, or
experiences a loss of power to the chiller electronics .
System 1 alarm contacts are located at TB1 – terminals
29 to 30. System 2 alarm contacts are located at TB1 –
terminals 31 to 32. The alarm contacts will close when
conditions allow the unit to operate, or the fault is reset
during a loss of power, the contacts will remain open
until power is reapplied and no fault conditions exist.

EMS-PWM REMOTE TEMPERATURE RESET

EMS-PWM Remote Temperature Reset is a value that
resets the Chilled Liquid Setpoint based on a PWM
input (timed contact closure) to the microboard. This
PWM input would typically be sup plied by an Energy
Management System.
JOHNSON CONTROLS
STAGE 1 STAGE 2
50% -
66% 33%
50% -
80% 40%
66% 33%
A contact closure on the PWM Temp Reset input at
CTB1 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 contact closure of 11 seconds. This is the longest con-
tact 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 between 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
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 dis played 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
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 program ming section under Cooling Setpoints.
Programmable values are from 2°F to 40°F (1.11°C to 11.11°C).
SECTION 8 - UNIT OPERATION
10
141
8