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Table 2: AirSmart Multi-Machine Sequencing Settings
3.5 Programmable IO Configuration
Next, the System Pressure input needs to be assigned on the Programmable IO settings page.
The AirSmart protocol requires a pressure sensor input representing the system pressure that is
measured at the system storage in order for a machine to be considered capable of being a
master on the network. An additional system pressure transducer connected to an open analog
input on the IO module at X11 is typically used for this and will need to be properly addressed.
The system pressure transducer shown in the diagram above in Figure 4
is connected to Analog
Input 3 on the IO module. The mapping of this location would correspond to Channel 3 for the
Sequence System Pressure, as shown below in Figure 15.
Machine delivery pressure may also be used in place of the system pressure transducer, if
desired. This is only recommended for small installations where there is little differential between
the delivery pressure and the system pressure, as well as between the delivery pressure of the
machines in the sequencing network. In this case, the channel that is assigned to Delivery
Pressure may be assigned to System Pressure on the Programmable IO configuration and the
controller will use this pressure signal for both purposes. On many machines, delivery pressure is
on Analog Input 2, but refer to the wiring diagram for your machine to verify this value.
Settings
Default Values
Description
Unit Number
1
A number between one and eight assigned to each machine in sequence. No two
machines can share a unit number.
Transfer
Interval
4 hours
Controls how frequent the Leader role is transferred. The leader role will be transferred
to another capable master of the same capacity when the difference between the run
hours of the two machines is equal to the Transfer Interval.
Fault Action
Local
This value may be set to Local or Wait. Indicates what a slave compressor (one that
cannot become master because no system pressure transducer is assigned) should do
when it no longer receives data from a master compressor. Local: modulate the pressure
based on the compressor’s own delivery pressure sensor and use the compressor’s own
set points. Wait: blowdown and stop compressor until communication with a valid master
compressor is reestablished. Note that the AirSmart controller does not have this setting
and will utilize the Wait behavior described above.
Lag Start
Delay
15 seconds
The Lag Start Delay is a value in seconds that sets amount of time the Master will wait
between commands to other machines in the system. This ensures that machines are
not brought on or offline too quickly. In most cases the default value of 15 seconds
should be used.
Capacity
700 CFM
Capacity value in CFM used to decide which machine is the Master in the sequence.
The largest machine capable of running as a master will always be the master in the
sequence, so Capacity values must be set to the same value for all machines that you
wish to rotate as the master of the system.
Transfer Load
Decrement
35%
Transfer Load Decrement sets the minimum percent load the network will run before
unloading one of the slave compressors due to pressure exceeding the unload setpoint.
Transfer Load
Increment
80%
Transfer Load Increment sets the maximum percent load the network will run before
loading another slave to meet demand.
Hour Offset
0 hours
The Hour Offset can be used to equalize maintenance hours of master machines on the
network. For example, if machine A has 100 hours and machine B has 25000 hours, the
Hour Offset on machine A could be set to 24900 hours so that the transfer interval
calculation would consider that the machines had equal run time.
Summary of Contents for Governor
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