The Turbo Air® 3000 Centrifugal Compressor Compressor Handbook

The Turbo Air 3000 Centrifugal Compressor Operator’s Manual
Main Drive Motor Controls
The major functions of a motor-control system are:
· Starting and stopping of the motor.
· Governing motor speed, torque, output (horsepower/kilowatts), and other characteristics.
· Protecting personnel and equipment.
When the main drive motor controller is purchased along with the compressor, Cooper
Turbocompressor specifies the proper hardware and design for easy compatibility with the compressor’s
Vantage Microprocessor Control System.
Cooper Turbocompressor Engineering Specification EDR-G-009, Requirements for Owner-Supplied
Motor Controls, completely details the minimum requirements for proper interface between the
compressor control system and the owner-supplied motor control equipment. However, because there
are different types of motor starting equipment and an even wider variety of optional features available,
many factors have to be considered when making an appropriate choice.
There are two general categories of starters for single speed, squirrel cage induction motors, full
voltage starters and reduced voltage starters. When selecting the motor controls, consider the following
information about these two types.
Full Voltage Starters
These apply full-line voltage directly to the motor terminals and are available in many types, including
manual, magnetic, combination, and reversing. It is also possible to add several other functions to
improve protection or increase monitoring capability.
Reduced Voltage Starters
These systems, which limit the drive motor current inrush, work well when normal considerations for
use of reduced voltage starting are observed. Starting times for reduced voltage systems are generally
less than 30 seconds. However, with reduced voltage starters the compressor’s inlet guide vanes must
not be cycled open until the motor and compressor have reached full speed. (The Vantage Control
System has the capability to delay loading with a variable timer.)
Although two general types of reduced voltage starters are commonly used, stepped starters and solid
state starters, stepped starters have been shown to give more consistent and reliable performance. The
wide variety of solid state starting equipment, along with contributing effects of various options and/or
features, makes performance of solid state starters inconsistent and difficult to predict.
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CAUTION:
It is advisable to use stepped starters for reduced voltage motor controls.
In certain applications, solid state starter performance may be unreliable or inconsistent.
Refer to Cooper Turbocompressor Engineering Specification EDR-G-008, Solid State Starter Specifications,
for more information on minimal requirements for solid state starting equipment.