ABB DCS800, Hardware Manual

Page: 49 / 134

Planning the electrical installation
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3ADW000194R0611 DCS800 Hardware Manual f us
changes in the cooling air temperature and volume. Since the cooling air volume can
only be detected indirectly, a differential-pressure switch has been additionally
installed at the unit’s housing, always located close to the power terminals.
The resistance change proportional to the temperature is acquired and evaluated in
the unit’s software. If the temperature rises above the preset value, then first an
alarm will be signaled, and - if the temperature continues to rise - an error message.
The value to be set for this parameter must not be more than 5 degrees above the
permissible ambient temperature.
The differential-pressure switch compares the pressure inside the unit with the
normal atmospheric pressure. If the fan has been switched on and the unit door
closed (and no unit casings have been removed), the pressure switch will signal
“Cooling conditions ok”, which means the drive may be enabled. There is no need to
set any specific differential pressure (recommendation: center setting).
Thermal overload and short-circuit protection
The drive protects itself and the input and motor cables against thermal overload
when the cables are dimensioned according to the nominal current of the drive.
Mains cable (AC line cable) short-circuit protection
Always protect the input cable with fuses. Size the fuses according to local safety
regulations, appropriate input voltage and the rated current of the drive (see chapter
Technical Data) .
High-speed semiconductor fuses provide short-circuit protection, but don’t provide
thermal overload protection.