13-18-601 Page 26
SECTION 4
CONTROLS & INSTRUMENTATION
GENERAL DESCRIPTION
- The Gardner Denver rotary screw compressor package is pre-wired with all
electrical components suitable for the voltage and horsepower at time of order. It is necessary only to
connect the compressor unit to the correct power supply and to the shop air supply network - and to the
appropriate water supply if using the water-cooled variant. A standard single stage compressor package
consists of unitized module that houses a single rotary screw compressor, oil sump, separation, filtering,
and internal injection delivery system, a main drive motor, a VFD, an oil/air cooling system, IP54 electrical
enclosure to house VFD on common controller and a sound-attenuating enclosure. The various control
devices employed are described as follows:
Controller
- The compressor package features the AirSmart controller, which integrates all the control
functions under microprocessor control. Controller functions include safety and shutdown, compressor
regulation, operator control and advisory/maintenance indicators. The keypad and display provides a
logical and easily operated control of the compressor and indication of its condition. The controller is
factory adjusted for the compressor package, but allows tuning for specific applications.
NOTICE
Read the Operator’s Manual before operating the compressor. It is critical that
the detailed instructions for the controller, found in the controller manual
13-17-600, are read and understood. Once the appropriate parameters have
been selected into the controller, compressor operation may commence. For
your convenience, a “Quick Start” excerpt from the controller manual is shown
on Section 3.8
Press the red “STOP/RESET” button to clear any conditions (e.g., “Loss of Power” when electrical system
was energized) and start the unit by pushing the green “START” button. Since the unit is equipped with a
minimum pressure (80 psig, 5.5 bar) valve, no special procedure to maintain minimum reservoir pressure
is required.
Main VFD and Motor
– The compressor is driven by an inverter-duty electric motor, which in turn is
energized by a pulse-width modulated, variable frequency drive (commonly referred to as VFD). This
combination of components enables the compressor package to match the supply of compressed air
(e.g., flow capacity) to meet the customer’s demand in real time and in a step-less fashion. The
operational logic which govern the drive and motor-combination is supplied by the AirSmart controller and
it is based on the following basic rules:
•
The speed of the compressor is modulated (e.g., increased or decreased) until the desired system
discharge pressure is achieved.
The drive shares a common IP54 protected enclosure with the AirSmart controller and assorted electrical
hardware. Ventilation for the electronics is supplied forced air delivered by the heat exchanger cooling
fans and filtered by inlet and outlet filters. The motor is built with a TEFC protected frame and coupled to
the compressor via a NEMA-D flange. The drive includes adequate current overload protection for its
companion motor.
The drive and motor are designed to operate with 3ph-60Hz-460vac electrical power, which must be
installed in accordance with local (site) Electrical Code requirements.
