JOHNSON CONTROLS
66
FORM 160.79-O3
ISSUE DATE: 11/09/2018
SECTION 2 – OPTIVIEW CONTROL CENTER
Active LCHLT Setpoint
Displays the active temperature setpoint to which the
chiller is set to control liquid leaving the evaporator.
The Active Setpoint is a target to the Local, Remote or
BAS (ISN) LCHLT programmed setpoint, depending
on the control source selected. When the chiller is not
running, the Active Setpoint is set to Entering Chilled
Liquid Temperature - LCHLT Setpoint Start Offset
When the VSD starts, the Active LCHLT Setpoint is
ramped to the programmed LCHLT Setpoint at the
programmable LCHLT Setpoint Ramp Rate. When
the chiller is running, performing capacity control, any
change to the programmed LCHLT setpoint results in
a ramp from the old Active Setpoint value to the new
LCHLT setpoint value at the programmed LCHLT
Setpoint Ramp Rate.
Delta T
Displays the difference between the temperature of the
chilled liquid leaving the evaporator and the Leaving
Chilled Liquid Active Setpoint.
Control State
Displays the present source controlling the command
to the capacity control devices, based on conditions as
follows:
• Inactive - Capacity Control is not active
• Temperature Control - Capacity Control is active
with no overrides acting
• Input Current - Input Current Override is in con-
trol
• Motor Current - Motor Current Override is in con-
trol
• Condenser Pressure - Condenser Pressure Over-
ride is in control
• Evaporator Pressure - Evaporator Pressure Over-
ride is in control
• Low LCHLT - LCHLT low temperature Override
is in control
Load Limit
Displays if any load limiting control is acting on the
temperature control output to the capacity control de-
vices. The field indicates the following:
• Inactive - Capacity Control is not active
• None - No limit is in effect
• Input Current
• Motor Current
• Condenser Pressure
• Evaporator Pressure
Head Pressure
Displays the difference between condenser refrigerant
pressure and evaporator refrigerant pressure.
Lead Compressor
Displays which compressor is lead.
Capacity Control Output Devices
Displays the following for each of the devices that is
available: VSD (Variable Speed Drive if installed),
VGD (Variable Geometry Diffuser) or HGBP (Hot Gas
Bypass Valve if installed)
• Active Output (LED): Indicates which device is
currently selected by the control for manipulation.
• Command: Displays the output command from
the control to the device in Hertz to the VSD or in
percent of full open to the VGD or HGBP valve.
• Feedback: Displays the present speed feedback
from the VSD or present position feedback from
the VGD.
• Active Min: Displays the prevailing minimum
value to which the control to the device is limited,
based upon surge controls or operating limits.
• Control Mode: Displays whether the device is un-
der Automatic or Manual control or inactive.
Lag PRV Position
Displays the Pre-Rotation Vane position of the Lag
compressor.
PROGRAMMABLE
Select PRV Control
Allows a service technician to set the PRV to be manu-
ally controlled.
Select HGBP Control
Allows a service technician to set the Hot Gas Bypass
to be manually controlled.