Table of Contents
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 two-stage compressor package
consists of two sets of compressors, motors and VFD's with common oil separation/reservoir, oil
cooling/filtering/distribution system, air cooling/filtering system, IP54 electrical enclosure to house VFD's
and 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 provide the
operator with 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.
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.
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 Motors – Each 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 governs each drive and motor-combination is supplied by the AirSmart controller
and it is based on the following basic rules:
·
The speed of the 1st stage compressor is modulated (e.g., increased or decreased) until the desired
system discharge pressure is achieved.
·
The speed of the 2nd stage compressor is modulated until its power consumption equals that of the
1st stage.
The drives share a common IP54 protected enclosure with the AirSmart controller and assorted electrical
hardware. Ventilation for the electronics is supplied by a combination of dual intake air filters and dual
discharge air filters with electric fans. The motors are built with TEFC protected frames and coupled to
each compressor via a NEMA-D flange. Each drive includes adequate current overload protection for its
companion motor.
NOTICE
13-17-605
Page 28
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