MCAC-CTSM-2018-1
Flooded type water cooled screw chiller (MIC)
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7) control point settings
8) discrete output status of various devices
9) compressor motor starter status
10) optional spare input channels
11) current and voltage for each phase
12) frequency
g. Schedule Function:
The chiller controls shall be configurable for manual or automatic start-up and shutdown. In
automatic operation mode, the controls shall be capable of automatically starting and
stopping the chiller according to a stored user programmable occupancy schedule. The
controls shall include built-in provisions for accepting:
1) A minimum of two 365-day occupancy schedules.
2) Minimum of 8 separate occupied/ unoccupied periods per day.
3) Daylight savings start/end.
4) Minimum of 18 user-defined holidays.
5) Means of configuring an occupancy timed override.
6) Chiller start-up and shutdown via remote contact closure.
h. Service Function:
The controls shall provide a password protected service function which allows authorized
individuals to view an alarm history file which shall contain the last 25 alarm/alert messages
with time and date stamp.
i. Network Window Function:
Each chiller control panel shall be capable of viewing multiple point values and statuses from
other like controllers connected on a common network, including controller maintenance
data.
j. Chilled Water Reset:
The control center shall allow reset of the chilled water temperature set point based on any
one of the following criteria:
1) Chilled water reset based on an external 4 to 20 mA signal.
2) Chilled water reset based on a remote temperature sensor (such as outdoor air).
3) Chilled water reset based on water temperature rise across the evaporator.
k. Demand Limit:
The control center shall limit amp draw of the compressor to the rated load amps or to a lower
value based on one of the following criteria:
1) Demand limit based on a user input ranging from 40% to 100% of compressor rated load
amps.
2) Demand limit based on external 4 to 20 mA signal.
l. Controlled Compressor Shutdown:
The controls shall be capable of being configured to soft stop the compressor.
2. Safeties:
a. Unit shall automatically shut down when any of the following conditions occur: (Each of these
protective limits shall require manual reset and cause an alarm message to be displayed on
the control panel screen, informing the operator of the shutdown cause.)
1) motor overcurrent
2) over voltage
3) under voltage
4) single cycle dropout*
5) bearing oil high temperature
6) low evaporator refrigerant temperature
7) high condenser pressure
8) high motor temperature
9) high compressor discharge temperature
10)
low oil pressure
11)
prolonged surge
