Unit Functions
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IOM 1242-8 • PATHFINDER
®
MODEL AWV CHILLERS
Unit Control States
The unit will always be in one of three states:
1.
Off – Unit is not enabled to run.
2.
Auto – Unit is enabled to run.
3.
Pumpdown – Unit is doing a normal shutdown.
T1 - Off to Auto
. All of the following are required:
• Unit is enabled
• No unit alarm requiring shutdown is active
• At least one circuit is enabled to start
• If unit mode = Ice, Ice Delay is not active
• Low Ambient Lockout is not active
•
Basic unit configuration is complete
•
Control system has rebooted since configuration changed
•
If Cond Fan Config = All Fan VFD, DC controller = Auto
T2 - Auto to Pumpdown
. Any of the following are required:
• Unit is disabled
• Unit Mode = Ice and LWT target is reached
• Unit alarm requiring normal shutdown is active
• Low Ambient Lockout is active
T3 - Pumpdown to Off
. Any of the following are required:
• Unit alarm requiring normal shutdown is active
• All circuits complete pumpdown
•
Cond Fan Config = All Fan VFD, DC controller = Auto
T4 - Auto to Off
. Any of the following are required:
• Unit alarm requiring normal shutdown is active
•
No circuits enabled and all circuits in Off state
Unit Status
Unit Status is displayed to indicate the general condition of the unit. The following table lists the text displayed for each unit 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 50: Unit Status Conditions
Enum
Status
Conditions
1
Auto
Unit State = Auto
2
Auto: Sound Reduction
Unit State = Auto and Sound Reduction is active
3
Off: Ice Mode Timer
Unit State = Off, Unit Mode = Ice, and Ice Delay = Active
4
Off: Low OAT Lockout
Unit State = Off and Low OAT Lockout is active
5
Off DC not ready
Unit State = Off, Condenser Fan Configuration = All Fan VFD, and DC controller is not in auto control
6
Off: All Cir Disabled
Unit State = Off and all circuits unavailable to start (temporary conditions are not considered)
7
Off: Unit Alarm
Unit State = Off and manual reset Unit Alarm active
8
Off: Keypad Disable
Unit State = Off and Unit Enable Set Point = Disable
9
Off: Remote Switch
Unit State = Off and Remote Switch input is off
10
Off: BAS Disable
Unit State = Off, Control Source = Network, and BAS Enable = false
11
Off: Unit Switch
Unit State = Off and Unit Switch input is off
12
Off: Test Mode
Unit State = Off and Unit Test Mode = On
13
Auto: Wait for Load
Unit State = Auto, no cooling is being provided (either mechanical or WSE), and LWT is less than the
active set point + startup delta
14
Auto: Evap Recirculate
Unit State = Auto and Evaporator State = Start
15
Auto: Wait for flow
Unit State = Auto, Evaporator State = Start, and Flow Switch input is off
16
Auto: Pumpdown
Unit State = Pumpdown
17
Auto: Max Circuit Run
Unit State = Auto, Unit Mode = Cool, number of running circuits is limited by the Max Cir Run set point
18
Auto: Unit Cap Limit
Unit State = Auto, unit capacity limit has been met or exceeded
19
Auto: RapidRestore
Unit State = Auto, unit is performing RapidRestore operation
20
Off: Invalid Config
The unit configuration is not a valid combination or not complete.
21
Off: Cfg Chg, Rst Ctlr
Unit configuration set point has changed, and reboot of controller is required
22
Off:Sending VFD Config
Controller is configuring the compressor VFD’s (Yaskawa only) via Modbus communication.
3
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