Danfoss vlt FC 102 Operating Instructions Manual

Also see for VLT HVAC Drive FC 102: Operating instructions Service guide Programming guide Installation guide Installation guide

8.2.4. Derating for Low Air PressureThe cooling capability of air is decreased at lower air pressure.At altitudes higher than 2 km, please contact Danfoss regarding PELV.Below 1000 m altitude no derating is necessary but above 1000 m the ambient temperature (TAMB) or max. output current (Iout) should be derated inaccordance with the shown diagram.Illustration 8.1: Derating of output current versus altitude at TAMB, MAX. By altitudes above 2 km, please contact Danfoss regardingPELV.An alternative is to lower the ambient temperature at high altitudes and thereby ensure 100% output current at high altitudes.8.2.5. Derating for Running at Low SpeedWhen a motor is connected to a frequency converter, it is necessary to check that the cooling of the motor is adequate.A problem may occur at low RPM values in constant torque applications. The motor fan may not be able to supply the required volume of air for coolingand this limits the torque that can be supported. Therefore, if the motor is to be run continuously at an RPM value lower than half of the rated value, themotor must be supplied with additional air-cooling (or a motor designed for this type of operation may be used).An alternative is to reduce the load level of the motor by choosing a larger motor. However, the design of the frequency converter puts a limit to themotor size.8.2.6. Derating for Installing Long Motor Cables or Cables with Larger Cross-SectionThe maximum cable length for this frequency converter is 300 m unscreened and 150 m screened cable.The frequency converter has been designed to work using a motor cable with a rated cross-section. If a cable with a larger cross-section is used, reducethe output current by 5% for every step the cross-section is increased.(Increased cable cross-section leads to increased capacity to earth, and thus an increased earth leakage current).VLT® HVAC Drive Operating Instructions 8. SpecificationsMG.11.A6.02 - VLT® is a registered Danfoss trademark 1538