Thermal Overload And Short Circuit Protection; Thermal Overload Protection; Protection Against Short-Circuit In The Motor Cable; Protection Against Short-Circuit In The Supply Cable Or The Drive - ABB ACS850-04 Hardware Manual

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Thermal overload and short circuit protection

Thermal overload 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. 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.

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 in the supply cable or the drive

Protect the supply cable with fuses or circuit breakers. Fuse recommendations are
given in chapter
gG fuses or UL type T fuses will protect the input cable in short-circuit situations,
restrict drive damage and prevent damage to adjoining equipment in case of a short
circuit inside the drive.

Operating time of the fuses and circuit breakers

Check that the operating time of the fuse is below 0.5 seconds. The operating
time depends on the type, the supply network impedance, and the cross-sectional
area, material and length of the supply cable. US fuses must be of the "non-time
delay" type.

Circuit breakers

The protective characteristics of circuit breakers depend on the supply voltage as
well as the type and construction of the breakers. There are also limitations
pertaining to the short-circuit capacity of the supply network. Your local ABB
representative can help you in selecting the breaker type when the supply network
characteristics are known.
Planning the electrical installation
Technical data. When placed at the distribution board, standard IEC