York YK Style H Operation Manual page 129

Table 129: Programmable
V09 software
Button
and earlier
Quick Start
Admin
Mode
Quick Pulldown
Service
Setpoint Offset
Quick Ramp
Current Service
Threshold
Model YK Style H Centrifugal Liquid Chillers with OptiView Control Center
V10 and later
with YORK
Description
Chiller Access
Manager
(Enabled, Disabled; default Disabled)
This setpoint is used to Enable and Disable the Quick Start feature. It
can only be Enabled when the Motor Drive Type Setpoint is set to VSD
or MVVSD. If Heat Pump Duty is enabled, the Quick Start feature is only
available when the Heat Pump Operational mode setpoint is set to
Cooling.
The default is Disabled. Quick Start can only be enabled using an Admin
password. When logged in at Admin access level, a Quick Start key will
appear on the Setpoints Screen. Pressing this key will navigate to the
Admin
Quick Start Screen where this setpoint is used to enable/disable the
feature.
Quick Start can be Disabled when logged in at Service access level.
However, once Disabled, it requires an Admin password to enable it again,
as explained previously. Quick Start mode will be automatically disabled
when any of the following occur: The Motor Drive Type is changed to
something other than VSD or MVVSD, or the Motor Communications
Protocol is changed to YORK, or the Heat Pump Duty (if enabled)
Operational Setpoint is set to Heating mode.
(0°F to 10°F; default 5°F)
This setpoint sets the Leaving Chilled Liquid Temperature at which
the control transitions from Quick Start mode to normal operation.
It is entered in the form of an offset above the active Leaving Chilled
Liquid Temperature (LCHLT) Setpoint. Once the Leaving Chilled Liquid
Temperature falls below the Active LCHLT Setpoint plus Quick Pulldown
Setpoint Offset, PRV (Quick Restart) and speed control (Quick Restart and
Quick Normal Start) revert to normal automatic control. Lower values of
this offset result in faster pulldown times but can result in overshoot of
the LCHLT Setpoint. Setting the value to its minimum of 0 results in the
JCI Service
fastest pulldown time but nearly always results in setpoint overshoot.
Depending upon how close the Low Chilled Liquid Temperature shutdown
threshold is to the LCHLT Setpoint, this could result in a LOW CHILLED
LIQUID TEMPERATURE cycling shutdown.
The Leaving Chilled Liquid Temperature and setpoint is shown on the
Quick Start Screen for reference. This setpoint sets one of the two
setpoints that determine when the control transitions from Quick Start
mode to normal operation. The other is the Pulldown Override Time
below.
(20% to 80% FLA; default 50%) This setpoint sets the motor current
threshold where the VSD speed command ramp rate changes. At or below
this threshold the speed command ramp is 4X of standard control.
Over this threshold, the ramp rate is 2X of standard control until it hits the
JCI Service
standard current limiting over 80% FLA.
Higher current thresholds can result in faster pulldown times. However,
setting this value too high can result in slower pulldown times due to
hitting the current limit sooner on pulldown.
129