JOHNSON CONTROLS
16
FORM 160.81-O1 (1020)
ISSUE DATE 10/05/2020
SECTION 1 - DESCRIPTION OF SYSTEM AND FUNDAMENTALS OF OPERATION
• With software version C.OPT.05.08.303 (and ear-
lier), it is 60 seconds.
• With software version C.OPT.05.09.303 (and later),
the duration is determined by the motor current
when the shutdown command is received as follows:
- 100% FLA or above equals 30 seconds.
- 75% FLA and below equals 5 seconds, lin-
ear between 75% and 100% FLA.
In multiple chiller applications it may be possible for
the chilled liquid (Water or Brine) from an operating
chiller to flow through the Evaporator of a standby
chiller. This represents a possible freeze threat to the
Condenser of the standby chiller. The
Standby Chiller
Freeze Protection
feature minimizes this freeze po-
tential by allowing the OptiView™ Control Center of
the standby chiller to cycle the condenser pump based
on the standby chiller’s Condenser Saturation Tem-
perature while it is shutdown. At chiller shutdown, the
pump runs until the condenser saturation temperature
increases to more than 35.0ºF, whereupon the pump is
turned OFF. While the chiller is shutdown, the condens-
er saturation temperature is monitored. If it decreases
to less than 30.0ºF, the pump is turned ON and runs un-
til the temperature increases to more than 35.0ºF. After
the chiller has been shutdown for at least the time delay
programmed as the Freeze time setpoint, and the tem-
perature decreases to less than 28.0ºF, “WARNING –
FREEZE THREAT FROM OPERATING CHILLER”
is displayed and alarm output is activated. When the
temperature increases to 28.0ºF, the warning message
and alarm output automatically clear. If this feature is
desired, Freeze Warning must be enabled by a Service
Technician. A complete description of this feature is
contained in the OptiView Control Center Service In-
structions (Form 160.81-M1).
Motor current overload protection is provided by the
CM-2 Board (Electro-Mechanical Starters) and Liq-
uid Cooled Solid State Starter. The overload is a timed
function beginning at 105% of the Chiller Full Load
Amps. With software version C.OPT.05.07.xxx (and
later), there is also a motor current overload provided
by the Microboard software. It also starts at 105% of
the chiller Full Load Amps and is adjustable over the
range of 12 (default) to 40 seconds with the 105% Mo-
tor Current Time setpoint. When the motor current has
exceeded 105% of Chiller FLA continuously for the
programmed time period, a safety shutdown is per-
formed and “105% Motor Current Overload” is dis-
played on the System Details Line of the Display.
The coolant temperature inside any JCI-supplied
liquid-cooled motor starter must be maintained
above the dewpoint temperature in the equipment
room to prevent condensing water vapor inside the
starter cabinet. Therefore, an additional temperature-
controlled throttle valve is needed in the flow path
for the starter heat exchanger to regulate cooling
above the equipment room dewpoint for applica-
tions using cooling sources other than evaporative
air-exchange methods, such as wells, bodies of wa-
ter, and chilled water. The temperature control valve
should be the type to open on increasing drive cool-
ant temperature, fail-closed, and set for a tempera-
ture above dewpoint. It can be requested as factory-
supplied on a chiller order by special quotation.
