Daikin Navigator WWV - Circuit Status Indicators; Compressor Control Methods; Compressor Cycle Timers

OPERATION
NAVIGATOR WWV/TWVDAIKIN APPLIED
38
• Unit state is O󰀨
• Rapid stop alarm occurs on the circuit
• Evaporator State is not Run
• Condenser State is not Run
T6 – Start to O󰀨 - Any of the following are required:
• Unit state is O󰀨
• Rapid stop alarm occurs on the circuit
• Evaporator State is not Run
• Condenser State is not Run
T7 – Start to Shutdown - Any of the following are required:
• Unit capacity control logic requires this circuit to stop
• Unit state is shutdown
• A normal shutdown alarm occurs on the circuit
• Control Source = Network and BAS Circuit Mode = O󰀨
Circuit Status
Circuit Status is displayed to indicate the general condition of the
circuit. The following table lists the text displayed for each circuit
status and the conditions that enable each status. If more than
one status is enabled at the same time, the highest numbered
status overrides the others and is displayed.
Table 30: Circuit Status
# Status Conditions
0 O󰀨: Ready Circuit is ready to start when needed.
1 O󰀨: Cycle Timer
Circuit is o󰀨 and cannot start due to active
cycle timer.
2
O󰀨: Max Starts
Per Hour
Circuit is o󰀨 and cannot start due to com-
pressor reaching max starts per hour.
3 O󰀨: BAS Disable
Circuit is o󰀨 and cannot start due to BAS
Circuit Mode input being set to O󰀨.
4 O󰀨: Alarm
Circuit is o󰀨 and cannot start due to active
circuit alarm.
5 Shutting Down Circuit is in shutdown state.
6 Run: Normal
Circuit is in start or run state and running
normally.
7 Run: DSH Low
Circuit is in start or run state and cannot
load due to low discharge superheat.
8
Run: Evap Press
Low
Circuit is in start or run state and cannot
load due to low evaporator pressure.
9
Run: Cond Press
High
Circuit is in start or run state and cannot
load due to high condenser pressure.
10
Run: VFD Input
Current High
Circuit is in start or run state and cannot
load due to high VFD input current.
11
Run: VFD Out
Current High
Circuit is in start or run state and cannot
load due to high VFD output current.
12
Run: VFD Temp
High
Circuit is in start or run state and cannot
load due to high VFD temperature..
13
Run: High LWT
Limit
Circuit is in start or run state and cannot
load due to the evaporator LWT exceeding
the limit for allowing full capacity.
Compressor Control
The compressor is controlled via:
• commands to the VFD via Modbus to start/stop the
compressor
• a speed command to the VFD via Modbus to control the
compressor speed
• a digital output to control the oil return solenoid valve and
jet pump solenoid valve
• digital outputs for compressor VR solenoids to control VR
Cycle Timers
A minimum time must pass between starts of each compressor.
When the compressor starts, a timer starts which will run for a
time determined by the Start-Start Timer set point.
A minimum time must pass between the stop and start of each
compressor as well. When the compressor stops, a timer starts
which will run for a time determined by the Stop-Start Timer set
point.
While either timer is running the compressor cannot start. Both
cycle timers will be enforced even through cycling of power to the
chiller. These timers may be cleared via the Clear Cycle Timers
set point.
Starts Per Hour Limit
In addition to the cycle timers, a limit of four starts per hour
is enforced. A bu󰀨er of start times for the last four starts is
maintained. If the current time is an hour or less after the rst
timestamp in the bu󰀨er, the next start will be delayed. This limit is
cleared if the Clear Cycle Timers set point is set to Yes.
Capacity Control
The compressor will vary capacity via changes to the motor
speed (frequency). The speed is controlled via writing to a
specic modbus register in the VFD. The VFD should initiate
the compressor to run when the circuit state is Start, Run, or
Shutdown.
Auto Capacity Control
The minimum running speed is set to 14 Hz and the normal
speed change is 1hz for all compressor congurations.
Circuit State = O󰀨 - Speed command is 0 Hz.
Circuit State = Start - Immediately after starting, the compressor
speed will be set to a frequency at least equal to the calculated
Compressor Minimum Frequency, which minimum is 14 Hz.
Circuit State = Run - After the circuit enters the Run state for 30
seconds, changes to the speed are performed based on load and
unload commands coming from the unit capacity control logic.
The speed is constrained to a range from the minimum based
on the conguration up to the Compressor Maximum Speed set
point.
When a capacity increase occurs a time delay starts and when
a capacity decrease occurs a separate time delay starts. While
either of these delays is active, no normal capacity changes will