Danfoss VLT FCD 311 Design Manual

Also see for VLT FCD 303: Operating instructions

Contents

Danfoss VLT FCD 311 Design Manual Manual pdf 120 page image

VLT® FCD Seriesswitch frequency can be based on the load, the am-bient temperature, the supply voltage and the cablelength.The function ensures that the frequency converterautomatically adjusts the switch frequency betweenf sw,min and fsw, max (parameter 411), see drawing be-low. Derating for air pressureBelow 1000 m derating is not necessary.Above 1000 m the ambient temperature (T AMB) ormax. output current (I MAX) must be derated in accor-dance with the diagram below:1. Derating of output current versus altitude at T AMB= max. 40 C.2. Derating of max. T AMB versus altitude at 100%output current. Derating for running at low speedWhen a motor is connected to a frequency con-verter, it is necessary to ensure adequate cooling ofthe motor. At low rpm values, the motor fan is notable to supply an adequate volume of cooling air.This problem occurs when the load torque is con-stant (e.g. with a conveyor belt) across the fullregulating range. The reduced amount of ventilationdetermines the permissible torque in continuous op-eration. If the motor is to run continuously at an rpmlower than half the rated value, extra cooling air mustbe supplied to the motor. Instead of providing extracooling, it is possible to reduce the motor load ratio.This can be done by selecting a larger motor. How-ever, the design of the frequency converter putslimits on the size of motors that can be connected tothe frequency converter. Motor cable lengthsThe frequency converter has been tested using a 10m unscreened/unarmoured cable and a 10 mscreened/armoured cable and has been designed towork using a motor cable with a rated cross-section. Vibration and shockThe frequency converter has been tested accordingto a procedure based on the following standards:IEC 68-2-6: Vibration (sinusoidal) - 1970.IEC 68-2-34: Random vibration broad-band -general requirements.IEC 68-2-35: Random vibration broad-band -high reproducibility .IEC 68-2-36: Random vibration broad-band -medium reproducibility. Air humidityThe frequency converter has been designed to meetthe IEC 68-2-3 standard, EN 50178 item 9.4.2.2/DIN 40040 class E at 40 C. UL StandardThis device is UL-approved. EfficiencyTo reduce energy consumption it is very important tooptimize the efficiency of a system. The efficiency ofeach single element in the system should be as highas possible.MG.04.A1.02 - VLT is a registered Danfoss trade mark120