JOHNSON CONTROLS
73
SECTION 2 – OPTIVIEW CONTROL CENTER
FORM 160.79-O3
ISSUE DATE: 11/09/2018
2
Low Load and Low Load Time
Access Level Required: SERVICE
Allows the user to define the criteria that determines
if the lag compressor should be shutdown because
the lead compressor is meeting the load requirement.
After the 30 minute Minimum Run Time (see
above), if the lead compres-
sor motor current goes below the Low Load Setpoint
(20% to 60%; default 45%) for a period of time equal
to the Low Load Time Setpoint (1 to 20 minutes; de-
fault 5), a Soft Shutdown will be performed on the lag
compressor.
PROGRAMMABLE
Compressor Lockout
Access Level Required: OPERATOR
Allows the user to lockout compressor #1 or #2. When
locked out, the selected compressor will be prevented
from running.
A compressor can be locked-out while both compres-
sors are running, without shutting down the entire
chiller. A soft shutdown will be performed on the run-
ning compressor selected for lockout and its status is
changed to lag (if not already the lag compressor al-
ready). Upon completion of coastdown, the selected
compressor will remain locked out until the lockout is
released. With previous software versions, a compres-
sor can be locked-out only while it is shutdown.
Compressor Mode
Access Level Required: OPERATOR
Allows the user to select Staged, Single, or Dual
Compressor operating mode.
Staged Mode - The second compressor is brought on
line to meet the load requirement.
Single Mode - The operation is restricted to one com-
pressor only. When starting the chiller in Single Com-
pressor mode, the operator does not designate which
compressor will run. Rather, the “Lead” compressor
is automatically selected by the software per normal
operation. The “lag” compressor will not be brought
on line, regardless of the load requirement. If Single
Compressor Mode is selected while both compres-
sors are running, a soft shutdown is performed on the
“Lag” compressor. All faults for this inhibited com-
pressor are continued to be handled. If the chiller is
shutdown while running in Single Compressor mode,
the software selects the “Lead” compressor as it nor-
mally does on a subsequent restart.
Dual Mode - This mode is only available when the
starters are either VSD or MVVSD. Both of the com-
pressors are started and stopped together and act as one
compressor.
NAVIGATION
Home
Access Level Required: VIEW
Causes a return to the Home screen.
Capacity Control
Access Level Required: VIEW
Causes a return to the Capacity Control screen.