ABB ACH550-02-645A-4 [35/454] Protection against short circuit in the motor and motor cable

Preparing for installation 31

ACH550-02 User’s Manual

protection function that protects the motor and switches off the

current when necessary. Depending on a drive parameter (see

parameter 3501

SENSOR TYPE), the function either monitors a

calculated temperature value (based on a motor thermal model,

see parameters 3005 MOT THERM PROT … 3009 BREAK POINT

FREQ) or an actual temperature indication given by motor

temperature sensors (see Group 35: MOTOR TEMP MEAS).

The user can tune the thermal model further by feeding in

additional motor and load data.

The most common temperature sensors are:

• motor sizes IEC180…225: thermal switch (e.g. Klixon)

• motor sizes IEC200…250 and larger: PTC or PT100.

Protection against short-circuit in the motor and

motor cable

The drive protects the motor cable and 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

Arrange the protection according to the following guidelines.

Circuit diagram Short-circuit

protection

Protect the

drive and input

cable with

fuses or a

circuit breaker.

See footnotes

1) and 2).

Distribution

board

Input cable

I >

Drive