Daikin AGZ080E - RapidRestore Option

IOM 1206-7 • TRAILBLAZER
™
MODEL AGZ CHILLERS 68 www.DaikinApplied.com
UnIT fUnCTIons
RapidRestore
®
Option
RapidRestore
®
is an option that can be added to Trailblazer
™
chillers. The general purpose of the option is to allow the
capability to restart more quickly and to load faster than normal
operation.
Enabling
The RapidRestore
®
option shall be enabled via the
RapidRestore
®
set point and requires the optional module.
Doing so will require the following to be true:
• RapidRestore
®
module is present at address 22
• DI1 on the RapidRestore
®
module has a signal
If the DI1 input loses the signal or the RapidRestore
®
module
is no longer communicating, then the option will be disabled in
the chiller.
Operation Following Power Cycle
The chiller will enter RapidRestore
®
upon powering up when
the following conditions are met:
• RapidRestore
®
is enabled
• Power failure lasts less than the value of the Max Power
Failure Time set point
• Power failure lasts at least one second (shorter power
loss may result in unpredictable operation)
• Unit is enabled
When RapidRestore
®
is triggered, the time value used for the
evaporator recirculation time will be limited to 110 seconds
or less. The evaporator recirculation time set point will not be
changed. Only the value used in the evaporator state logic will
be limited, and only if the set point exceeds the 110 second
limit.
This action will ensure that the chiller is ready to start after the
motor protection module delay has expired.
Time to Start
The compressor manufacturer requires a minimum two minute
delay after power on until a compressor should be started,
which is to ensure proper operation of the motor protection
modules. Unit controller boot time is about 10 seconds, so a
delay of 110 seconds will start upon completing boot up. After
this delay, the two minute manufacturer requirement will be
satised.
After the 110 second delay, the rst circuit to start will enter the
preopen state, which takes ve seconds. The end result is that
the rst compressor should start approximately 125 seconds
after power is restored to the chiller.
Current software has a delay of 150 seconds after bootup is
complete before the rst circuit can start. The software will be
changed to use the 110 second delay discussed above only
when the chiller is performing the RapidRestore operation.
Fast Loading
Fast loading will be performed when the following conditions
are met after the unit power up:
• Chiller enters RapidRestore
®
operation
• Current LWT > Start Up Temperature
For reference, Start Up Temperature is Stage Up Temperature
+ Start Up Delta T. Stage Up Temperature is calculated based
on the Full Capacity Evaporator Delta T set point and the
number of compressors on the chiller.
Fast loading should end if any of the following conditions occur:
• LWT < Stage Up Temperature
• Unit capacity = 100%
• All circuits become disabled for any reason
• Unit becomes disabled for any reason
• 10 minutes have passed since unit powered up
When fast loading ends, the RapidRestore
®
operation is
considered complete.
Capacity Changes
Normally the delay between compressors staging on is
determined by the Stage Up Delay setting. That setting
defaults to 240 seconds and has a range of 120 to 480
seconds. During fast loading, a delay of 60 seconds between
compressor starts within a circuit should be used. In addition,
a delay of 30 seconds between compressor starts on different
circuits should be used.
This change during RapidRestore
®
operation will allow for a
faster time to full capacity while maintaining stable operation
within each circuit. Assuming both circuits are able to run, the
effective unit stage up delay will be 30 to 35 seconds, so it will
load about four times faster during RapidRestore
®
than the
fastest it possibly can during normal operation.
Max Pulldown Rate
Max pulldown rate will be ignored during fast loading so the
chiller can reach full capacity as soon as possible.
Backup Chiller Operation
If DI2 on the RapidRestore
®
module has a signal and the unit
has RapidRestore
®
enabled, then the chiller is considered a
‘backup chiller’. When a ‘backup chiller’ is enabled, it will use
an evaporator recirculation time of 13 seconds regardless of
what the evaporator recirculation time set point is. Then, fast
loading will be used as outlined previously in the fast loading
section.
This backup chiller sequence is safe for the unit if it has had
power applied for the minimum time stated in the operation
manual. Since this sequence does not have to wait on the
compressor motor protection module delay, the unit can
achieve full capacity even faster than during a power loss
scenario.