Product Manual

Drives, like any power conversion device, create certain power
disturbances (called “noise” or “harmonic distortion”) that are reflected
back into the power system to which they are connected. These
disturbances rarely affect the drive itself but can affect other electrically
sensitive components.
Control Complexity: Even small, low-cost AC drives are now being
produced with impressive features, including an array of programmable
functions and extensive input and output capability for integration
with other components and control systems. Additional features may
be offered as options. Vector drives, as indicated previously, are one
example of enhanced control capability for specialized applications.
In addition, nearly all drives provide some measure of fault logging
and diagnostic capability. Some are extensive, and the easiest to
use display the information in words and phrases rather than simply
numerical codes.
Environmental Factors: The enemies of electronic components are
well-known. Heat, moisture, vibration and dirt are chief among them
and obviously should be mitigated. Drives are rated for operation in
specific maximum and minimum ambient temperatures. If the maximum
ambient is exceeded, extra cooling must be provided, or the drive
may have to be oversized. High altitudes, where thinner air limits cool-
ing effectiveness, call for special consideration. Ambient temperatures
too low can allow condensation. In these cases, or where humidity is
generally high, a space heater may be needed.
Drive enclosures should be selected based on environment. NEMA 1
enclosures are ventilated and must be given room to “breath.” NEMA
4/12 enclosures, having no ventilation slots, are intended to keep
dirt out and are also used in washdown areas. Larger heat sinks
provide convection cooling and must not be obstructed, nor allowed
to become covered with dirt or dust. Higher-horsepower drives are
typically supplied within NEMA-rated enclosures. “Sub-micro” drives,
in particular, often require a customer-supplied enclosure in order to
meet NEMA and National Electrical Code standards. The enclosures of
some “micro” drives, especially those cased in plastic, may also not be
NEMA-rated.
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