Sullivan-Palatek UD Series, User Manual

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26 COMPONENT DESCRIPTION
3.1 AIR COMPRESSOR PACKAGE
The air compressor package consists of a rotary screw compressor unit, air-cooled/water-cooled lubrication
and cooling system, discharge system, intake and capacity control system and monitoring system.
3.2 COMPRESSION CYCLE
During operation, two helically-grooved rotors mesh to compress air. Intake air is compressed as the male
lobes roll down the female grooves, pushing trapped air along, compressing it until a female groove uncovers
the discharge port in the end of the stator and delivers smooth-flowing, pulse-free air to the receiver.
Atmospheric air fills in behind the male lobe, preparing the female groove for another compression cycle as
rotation continues and the male lobe again meshes with the female groove.
FIGURE 3-1.
COMPRESSION CYCLE
3.2.1 COMPRESSOR UNIT
The compression cycle takes place within the compressor unit (also referred to as an air end). The
compressor unit is a lubricant-flooded, positive displacement, single-stage rotary screw air end, designed to
achieve the desired operating pressure. The compressor unit’s main components include a stator housing,
discharge housing, male and female rotors, bearings and seals.
3.3 DRIVE SYSTEM
When started, the main motor starter contacts are pulled in and power is supplied to the motor. Power is
transferred from the motor to the compressor unit by the drive coupling to bring the compressor unit up
to operating speed. An adapter housing self-aligns the motor and compressor unit. The power status and
modes of operation are controlled through the starter assembly.
3.3.1 DRIVE MOTOR
The drive motor is the main electrical motor that powers the compressor unit. The electric motor is three-
phase induction type supplied with a C-flange that bolts directly to the motor/compressor adapter. Standard
motor configuration is a NEMA Premium ODP design. Optional motor configurations are available upon
request.
3.3.2 DRIVE COUPLING
The drive coupling transfers power from the drive motor to the compressor unit. The drive coupling
consists of two steel coupling halves (one for the motor shaft and one for the compressor unit shaft) and a
replaceable spider coupling element.
3.4 VFD (ELECTRICAL CONTROL PANEL)
The compressor’s Variable Frequency Drive (VFD) is sized to provide speed control and protection for the
main motor at the specified voltage. For air-cooled models an auxiliary VFD is used in conjunction with
the compressor VFD to provide variable cooling, dependent on the compressor’s demand and the ambient
conditions.
The Electrical Control Panel is NEMA 4/12 rated andprovides a standard high degree of protection against
the elements. The control panel houses the 120VAC main control power transformer, the 24VAC transformer
for supplying power to the microprocessor, the ausiliary VFD fuses (air-cooled models), circuit breakers for
ground/fault protection, and terminals for the intercommecting of exterior electrical components.
3.5 PROTECTIVE DEVICES
The compressor package is equipped with several safety devices to protect the equipment and the end user.
A pressure relief valve is mounted on the sump tank to prevent the compressor package from exceeding the
rated pressure of its components. Temperature and pressure sensors will send signals to the microprocessor
to shut down the compressor if temperature or pressure limits are exceeded.
3.5.1 PRESSURE RELIEF VALVE
The pressure relief valve will open to relieve excess pressure in the sump tank if the pressure exceeds the set