Thermal Overload Protection Of The Motor; Protection Against Short-Circuit In The Motor Cable; Protection Against Short-Circuit Inside The Drive Or In The Supply Cable; Earth Fault (Ground Fault) Protection - ABB ACS800-07-0610-3 Hardware Manual

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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 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.

Earth fault (Ground fault) protection

Both the supply unit and the inverter unit are equipped with an internal earth fault
protective function to protect the drive against earth faults in the drive, motor and
motor cable (This is not a personal safety or a fire protection feature). The function is
not active in the supply unit by default. Both earth fault protective functions can be
disabled; refer to User's Manual of the supply unit and the Firmware Manual of the
drive application program respectively.
See the ACS800 Ordering Information (3AFY64556568 [English], available on
request) for other available earth fault protection options.
The EMC filter (if present) includes capacitors connected between the main circuit
and the frame. These capacitors and long motor cables increase the earth leakage
current and may cause fault current circuit breakers to function.
Planning the electrical installation
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Technical data on page 120, or equivalent fuses. Six fuses are needed for