Monitoring The Dcs880 Power Section; Thermal Overload And Short-Circuit Protection; Mains Cable (Ac Line Cable) Short-Circuit Protection - ABB DCS880 series Hardware Manual

Monitoring the DCS880 power section

The power part of converters size H1 ... H6 is monitored by means of a galvanic
isolated PTC thermistor. The PTC is installed on the heat sink in an isolated
configuration. The PTC's resistance and protective effect correspond to the
maximum temperature defined by the type code.
The air entry temperature at the power part of converters size H7 and H8 is
monitored by means of a galvanic isolated PTC thermistor. The sensor measures
the power part's radiated heat and any changes in the cooling air temperature and
volume.
The resistance change proportional to the temperature is read and evaluated in the
drive's firmware. If the temperature increases above the preset value, then first a
warning and - if the temperature continues to rise - a fault message is generated.
The preset value must not be set more than 5 degrees above the permissible
ambient temperature.
Since the cooling air volume can only be detected indirectly, a differential-pressure
switch has been additionally installed at the unit's housing. It is always located close
to the power terminals.
The differential-pressure switch compares the pressure inside the drive with the
normal air pressure. If the fan is switched on, the drive's door is closed, no covers
have been removed and the pressure switch signals 'cooling conditions ok' it is
possible to release the converter. There is no need to set a specific differential
pressure (recommendation: use the center setting). The differential pressure switch
should be connected to the converter fan acknowledge signal.

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
High-speed semiconductor fuses provide short-circuit protection, but don't provide
thermal overload protection.
data).
3ADW000462R0101 DCS880 Hardware Manual e a
Planning the electrical installation
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