Protecting The Motor Against Thermal Overload - ABB ACS355 series User Manual

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Protecting the motor against thermal overload

According to regulations, the motor must be protected against thermal overload and
the current must be switched off when overload is detected. The drive includes a
motor thermal protection function that protects the motor and switches off the current
when necessary. It is also possible to connect a motor temperature measurement to
the drive. The user can tune both the thermal model and the temperature
measurement function further by parameters.
The most common temperature sensors are:
• motor sizes IEC 180...225: thermal switch (for example Klixon)
• motor sizes IEC 200...250 and larger: PTC or Pt100.
For more information on the thermal model, see section
page 148. For more information on the temperature measurement function, see
section Motor temperature measurement through the standard I/O
Implementing the Safe torque off (STO) function
See Appendix: Safe torque off (STO)
Using residual current devices (RCD) with the drive
ACS355-01x drives are suitable to be used with residual current devices of Type A,
ACS355-03x drives with residual current devices of Type B. For ACS355-03x drives,
other measures for protection in case of direct or indirect contact, such as separation
from the environment by double or reinforced insulation or isolation from the supply
system by a transformer, can also be applied.
Using a safety switch between the drive and the motor
It is recommended to install a safety switch between the permanent magnet
synchronous motor and the drive output. This is needed to isolate the motor from the
drive during maintenance work on the drive.
Implementing a bypass connection
WARNING! Never connect the supply power to the drive output terminals U2,
V2 and W2. Power line voltage applied to the output can result in permanent
damage to the drive.
If frequent bypassing is required, employ mechanically connected switches or
contactors to ensure that the motor terminals are not connected to the AC power line
and drive output terminals simultaneously.
Planning the electrical installation 47
on page 417.
Motor thermal protection
on page 157.
on