151.4.6 Motor Thermal ProtectionThe F5 series inverters are UL approved as a solid state motor overload protec-tion device. It is necessary to adjust the current trip level in parameter LF. orLF.12. The function assumes the use of a non-ventilated motor. The functionmeets the requirements set forth in VDE 0660 Part 104, UL508C section 42,NFPA 70 Article 430 part C. See the description for parameter LF. for the tripcharacteristics.A motor winding sensor can also be used for additional safety and the highestlevel of protection. Either a normally closed contact (rating: 15V / 6mA) or a PTC(positive temperature coefficient) resistor can be connected to the T1, T2 termi-nals on the inverter. The thermal device should be connected as indicated onpage 24.1.4.7 Motor Cable LengthIn some conventional installations and many MRL applications, the motor canbe a considerable distance (greater then 40 feet) from the elevator drive. Underthese circumstances the long cable length can cause high voltage peaks or highdv/dt (rate of voltage rise) on the motor windings. Depending on the design of themotor, these can lead to damage of the motor winding. Therefore, in these instal-lations use of a special dv/dt filter is highly recommended.The standard approved solution is special output choke designed for use with thea maximum of 16kHz switching frequency and low inductance so as not to drasti-cally influence the motor's equivalent circuit model.There are three sizes available for motors rated up to 136A. The part numbersand current ratings are listed below.Part Number Rated Current18Z1A05-1000 45A21Z1A05-1000 75A23Z1A05-1000 136AThe use of a conventional line or motor choke on the output of the drive is notrecommend since the inductance value is high enough that it would distort thevalues in the motor model and result in poor control of the motor.General
