Section 11
VARIABLE SPEED DRIVE APPLICATIONS
58
tion will apply to a compressor with an operating
range of 100 psig (6.9 bar). A compressor with any
other pressure range would operate in the same
manner except stated pressures. Supervisor con-
troller and VSD settings for 100 psig model can be
found in Table 11-1 Package Selection Chart.
START MODE- 0 – 50 PSIG (0 TO 3.5 BAR)
When the compressor “I” (START) pad is
depressed, the VSD ramps the motor to full speed
and the sump pressure will quickly rise from 0 to 50
psig ( 0-3.4 bar). During this period, both the regu-
lator and solenoid valves are closed, the inlet valve
is fully open and the compressor delivers full rated
capacity. The rising compressor air pressure is iso-
lated from the service line in this phase by the min-
imum pressure valve set at approximately 50 psig
(3.4 bar).
FULL LOAD MODE- 50 TO 100 PSIG (3.4 TO 6.9
BAR)
When the compressed air pressure rises over 50
psig (3.4 bar) the minimum pressure valve opens
allowing compressed air to flow into the service line.
From this point on the line pressure is continually
monitored by the supervisor controller and the vari-
able speed drive. The pressure regulator and sole-
noid valve remain closed with the inlet valve fully
open running at 100 psig (6.9 bar) or below.
VARIABLE SPEED DRIVE PART LOAD CON-
TROL
If less than rated capacity of compressed air is
Figure 11-1B Sullair Rotary Screw Air Compressor- 100HP Water-cooled with Variable Speed
(typical component layout)
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