Thermal Overload And Short-Circuit Protection; Thermal Overload Protection Of The Drive And The Input And Motor Cables; Thermal Overload Protection Of The Motor; Protection Against Short-Circuit In The Motor Cable - ABB ACS800 Hardware Manual

62

Thermal overload and short-circuit protection

Thermal overload protection of the drive and the input and motor cables

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. No
additional thermal protection devices are needed.
WARNING! If the drive is connected to multiple motors, a separate thermal overload
switch or a circuit breaker must be used for protecting each cable and motor. These
devices may require a separate fuse to cut off the short-circuit current.

Thermal overload protection of the motor

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. Depending on a drive parameter value, the function either monitors
a calculated temperature value (based on a motor thermal model) or an actual
temperature indication given by motor temperature sensors. The user can tune the
thermal model further by feeding in additional motor and load data.
See the Firmware manual of the drive application program for more information on
the motor thermal protection, and the connection and use of the temperature
sensors.

Protection against short-circuit in the motor cable

The drive protects the motor cable and the motor in a short-circuit situation when the
motor cable is dimensioned according to the nominal current of the drive. No
additional protection devices are needed.

Protection against short-circuit inside the drive or in the supply cable

• If the drive is equipped with internal AC fuses (option code +F260), install external
protection (such as fuses) at the supply to protect the input cable.
• If the drive is not equipped with AC input fuses, install external fuses at the supply
to protect the input cable and the drive. Use the AC fuse types listed in the
chapter
each DSU module.
WARNING! Circuit breakers are not capable of providing sufficient protection
because they are inherently slower than fuses. Always use fuses with circuit
breakers.
Planning the electrical installation
Technical data on page 128, or equivalent fuses. Six fuses are needed for