Auto-off manual switch guide

Some of the most common applications HVAC drives like the ACH580s are used in involve an Auto-Off-Manual switch, such as carpark exhaust fans, kitchen exhaust fans, and cooling tower fans. This Tech Tip will show you the basic parameter configurations you’ll need for your Auto-Off-Manual application.

In this example, a 3-position switch is used to change between auto, off, and manual modes, with the switch wired to DI1 and DI6. In auto mode (DI1), the drive will run using an analog input as a frequency reference, such as a CO sensor or pressure sensor. In manual mode (DI6), the drive will run at a constant frequency of 50Hz.

Navigate to the complete list of parameters by pressing Menu > Parameters > Complete List.

GROUP 12 (Standard AI)

12.15:
AI1 Unit Selection
V

12.17:
AI1 min
0.000

12.18:
AI1 max
10.000

12.19:
AI1 Scaled at AI1 Min
0.000

12.30:
AI2 Scaled at AI2 Max
50.000

GROUP 19 (Operation Mode)

19.11
Ext1/Ext2 Selection
DI6

GROUP 20 (Start/Stop/Direction)

20.01
Ext1 Commands
In1 Start

20.03
Ext1 In1 Source
DI1

20.06
Ext2 Commands
In1 Start

20.08
Ext2 In1 Source
DI6

GROUP 28 (Frequency Reference Chain)

28.11
Ext1 Frequency Ref1
AI1 Scaled

28.13
Ext1 Frequency Function
Ref1

28.15
Ext2 Frequency Ref1
Zero

28.17
Ext2 Frequency Function
Ref1

28.22
Constant Frequency Sel1
DI6

28.26
Constant Frequency 1
50Hz


That’s it! There may be some minor application-specific tweaks required, but you should be well on your way to getting your application up and running.

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