Ingersoll Rand X8I Mode D'emploi page 42

For example 2:
For a variable speed compressor that has been assigned a
maximum capacity output percentage of 60% (related to
the largest capacity), and is able to reduce speed to 30%
of maximum speed:
Example Compressor 4 is a VSD:
Max CFM = 420
Max Output Capacity 420/700 = 60%
Min CFM = 127 (30% or 420 x .30)
Min Output Capacity 127/700 = 18% (or 30% x 60% =
18%)
For example 3:
For a 3-step (0/50/100%) reciprocating compressor
that has been assigned a maximum capacity output
percentage of 60%, the minimum output capacity is the
half-output regulation step:
Minimum Output Capacity = 30%
% Minimum Efficiency
Only applicable for a variable output compressor
(IRV-485). Not shown for other types.
The minimum efficiency point is regarded as the speed, or
step, below which another smaller capacity compressor
in the system could achieve the equivalent output at a
higher efficiency.
The percentage value is directly related, and scaled, to the
maximum and minimum output percentage values.
For example:
Example: A Compressor is a VSD: Max CFM = 420 (Largest
Compressor is 700 CFM)
Max Output Capacity 420/700 = 60%
Min CFM = 127 (30% or 420 x .30)
Min Output Capacity 127/700 = 18% (or 30% x 60% =
18%)
If another compressor in the system is able to provide
40% of the compressor's full speed output more
efficiently, set the % Minimum Efficiency value to 24%
(40% x 60%). This percentage value represents 40% of
the full speed output of the compressor scaled to System
capacity.
When the compressor is detected as operating below the
% Minimum Efficiency value for a period of time the X8I
will immediately re-evaluate utilization and re-configure,
if possible, to utilize a the smaller capacity, more efficient
compressor, or combination of compressors. This process
is automatic and executed dynamically in accordance
with prevailing operational conditions at the time. The
ENER control mode algorithms will eventually conclude
the best compressor fit without this parameter; the %
Minimum Efficiency input will speed up this process.
The intent of this feature is to always operate the smallest,
most efficient compressor and to prevent a variable
output capacity compressor operating at minimal
speed, or minimal output, for prolonged periods of time.
Generally a variable output compressor operating at
minimal capacity is less efficient than a smaller capacity
compressor that is able to achieve the same output at
higher, or maximum, output capacity.
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