Sullair Supervisor 2 Deluxe, Operator'S Manual

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Section 3
SEQUENCING WITH VARIABLE SPEED DRIVE COMPRESSORS
3.1 VARIABLE SPEED DRIVE APPLICATIONS
Multiple compressor systems can be designed using a variable-speed-drive (VSD) com-
pressor combined with either fixed speed or other VSD compressors. The most efficient
use of a VSD machine in sequencing is to make it always be the trim machine and always
be running. This can be accomplished using the existing Sullair sequence logic.
3.2 SETUP FOR FIXED SPEED MACHINES AND A VSD COMPRESSOR
The fixed-speed machine(s) must be set up for load/unload operation. If controlled with
Supervisor II Deluxe controllers, the pressure regulator/s must be made to have no effect
by operating the system below their effective range. If controlled by the Supervisor
Controller, the controls may be programmed for Load/No load operation whereby the Full
Load valve is energized any time the machine is running, thus defeating modulation.
Alternately, the Full Load solenoid valve may be rewired to the Load output with either the
Supervisor Controller or Supervisor II Deluxe to accomplish the same thing. In any case
care must be taken to not overload these compressors by only operating at pressures with-
in the capability of the drive motor. See the following chart for suggested settings.
Since this machine is to always be the trim machine, no Full Load action is needed. The
Max Speed input signal should be disabled unless more than one VSD machine is in the
same sequence.
In this configuration, only the fixed-speed compressors are sequenced and the VSD is run
with its sequencing disabled. Sequence hours mode can then be used to automatically
rotate the fixed-speed machines, or you may select to sequence based on Com#.
Depending on the application and system demands, the VSD compressor can either be run
continuously or in the AUTO mode to minimize the unload time to as little as an immediate
stop on unload. In this arrangement, the VSD machine will always be operating as the trim
machine because it will restart at a higher pressure than the fixed-speed machines. By
adjusting the VSD Unload time in AUTO mode and the fixed-speed Restart times, rapid
cycling and hunting can be minimized.
Target system pressure at discharge of compressors: 99 psi
VSD Compressor Fixed-Speed Compressor(s)
Unload Setpoint 104 102
Load Delta 6 6
VSD Setpoint 99
Com # COM #1, 2 (, 3, 4, etc.)
Lowest Pressure 90
Since a fixed-speed L (100 psi) compressor's pressure regulator doesn't begin to throttle
until 101- 102 psi, it should have no effect, thereby causing the machine to operate
Load/Unload with or without the Full Load solenoid valve. The net result would have the
VSD always running and be able to modulate; the fixed-speed machines would come on
and go off as necessary but operate Load/Unload. Note that the normal load delta becomes
narrower while operating a sequenced system; the settings above will load at 97 and unload