6
JOHNSON CONTROLS
OptiView Control Center
- continued
Shutdown, a Safety Shutdown and a chiller Run Contact.
pressure transducers sense system pressures and therm-
istors sense system temperatures. The output of each
transducer is a DC voltage that is analogous to the pres-
sure input. The output of each thermistor is a DC voltage
that is analogous to the temperature it is sensing.
Setpoints can be changed from a remote location via
0-10VDC, 4-20mA, contact closures or through serial
communications. The adjustable remote reset range [up
to 20°F (11.1°C)] provides flexible, efficient use of remote
signal depending on reset needs. Serial data interface
to the YORK ISN Building Automation System (BAS) is
through the General protocol Interface Card (GpIC), which
can be mounted inside the Control Center.
This printed circuit board requests the required data from
the Micro Board and makes it available for the YORK
ISN network. This optional board is available through the
Johnson Controls BAS group. The operating program
is stored in non-volatile memory (epROM) to eliminate
chiller failure due to AC power failure/battery discharge.
programmed setpoints are retained in lithium battery-
backed RTC memory for 11 years minimum.
Smart Freeze point protection can operate the chiller as
low as 36°F (2.22°C) leaving chilled water temperature,
without nuisance trips on Low water Temperature. The
sophisticated program and sensor monitors the chiller wa-
ter temperature to prevent freeze-up. each programmable
point has a pop-up screen with the allowable ranges, so
the chiller cannot be programmed to operate outside of
its design limits.
Thermal ice storage systems are based on the concept
of using off-peak, lower cost electricity to build ice for
handling the cooling load during peak hours. The most
efficient way to build ice is to maximize chiller load and
minimize run time. Standard chiller control systems are not
designed for this operating mode. In a typical application,
chillers will load and unload to maintain a leaving chilled
liquid setpoint. when the YORK YS chiller operates in the
thermal storage control mode, the unit will remain at 100%
load until the setpoint shutdown temperature is reached.
To add greater operating flexibility and eliminate unnec
-
essary chiller cycling, two different Low water (Liquid)
Temperature Restart Thresholds can be programmed, one
for the ice mode and one for the standard cooling mode.
This control enhancement is standard on all YS chillers.
The chiller can also be left in the standard control mode
for temperatures ranging between 20 and 70°F (-6.7 and
21.1°C), for applications involving a process cooling duty
that requires leaving chilled liquid temperature setpoint
control.
when power is applied to the chiller, the
HOME
screen
is displayed. This screen displays a visual representation
of the chiller and a collection of data detailing important
operations and parameters. when the chiller is running,
the flow of chilled liquid is animated by the alternating
shades of color moving in and out of the pipe nozzles. The
primary values that need to be monitored and controlled
are shown on this screen. They are as follows:
Display Only:
• Chilled Liquid Temperature – Leaving
• Chilled Liquid Temperature – Return
• Condenser Liquid Temperature – Return
• Condenser Liquid Temperature – Leaving
• Motor Run (LeD)
• % Full Load Amps
• Operating Hours
with the “soft” keys the operator is only one touch away
from the 8 main screens that allow access to the major
information and components of the chiller. The 8 screens
are the
SYSTEM, EVAPORATOR, CONDENSER, COM-
PRESSOR, OIL SUMP, MOTOR, SETPOINTS,
and the
HISTORY.
Also on the Home Screen is the ability to
LOG
IN, LOG OUT
and
PRINT.
Log In and Log Out is the means
by which different security levels are accessed.
The
SYSTEM
screen gives a general overview of common
chiller parameters for both shells. This is an end view of
the chiller with a 3-D cutaway of both the shells. The fol-
lowing can be viewed from this screen:
Display Only:
• Discharge Temperature
• Chilled Liquid Temperature – Leaving
• Chilled Liquid Temperature – Return
• Chilled Liquid Temperature – Setpoint
• evaporator pressure
• evaporator Saturation Temperature
• Condenser Liquid Temperature – Leaving
• Condenser Liquid Temperature – Return
• Condenser pressure
• Condenser Saturation Temperature
• Oil Temperature
• Differential Oil pressure
• % Full Load Amps
• Current Limit
• Slide Valve position
