Planning the electrical installation41Thermal overload and short-circuit protectionThermal overload protection of the drive and the input and motor cablesThe drive protects itself and the input and motor cables against thermal overloadwhen the cables are dimensioned according to the nominal current of the drive. Noadditional thermal protection devices are needed.WARNING! If the drive is connected to multiple motors, a separate thermal overloadswitch or a circuit breaker must be used for protecting each cable and motor. Thesedevices may require a separate fuse to cut off the short-circuit current.Thermal overload protection of the motorAccording to regulations, the motor must be protected against thermal overload andthe current must be switched off when overload is detected. The drive includes amotor thermal protection function that protects the motor and switches off the currentwhen necessary. Depending on a drive parameter value, the function either monitorsa calculated temperature value (based on a motor thermal model) or an actualtemperature indication given by motor temperature sensors. The user can tune thethermal model further by feeding in additional motor and load data.The most common temperature sensors are:ï motor sizes IEC180Ö225: thermal switch (e.g. Klixon)ï motor sizes IEC200Ö250 and larger: PTC or Pt100.See the firmware manual for more information on the motor thermal protection, andthe connection and use of the temperature sensors.Protection against short-circuit in the motor cableThe drive protects the motor cable and motor in a short-circuit situation when themotor cable is dimensioned according to the nominal current of the drive. Noadditional protection devices are needed.
