Planning the electrical installation
39
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 the chapter Technical data. When placed at the distribution board, standard
IEC 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.
Motor thermal protection
According to regulations, the motor must be protected against thermal overload and
the current must be switched off when overloading 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.
The ACSM1-04 has a dedicated connection for PTC or KTY84 sensors. See page
60 in this manual, and the appropriate Firmware Manual for the parameter settings
concerning motor thermal protection.
Ground fault protection
The drive is equipped with an internal ground fault protective function to protect the
unit against ground faults in the motor and the motor cable. This is not a personal
safety or a fire protection feature. The ground fault protective function can be
disabled with a parameter, refer to the appropriate Firmware Manual.
The internal mains filter includes capacitors connected between the main circuit and
the frame. These capacitors and long motor cables increase the ground leakage
current and may cause fault current circuit breakers to function.
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