VLT ® 2900 Series Special conditions ticles are typically observed on top of installation cab- inets and on existing electrical installations. Indicators that there are aggressive gases in the air are copper rails and cable ends that are black on existing electrical installations. As all other electronic equipment, a frequency con- verter contains a number of mechanical and electronic components, which to a varying extent are vulnerable to environmental impact. Aggressive environments Consequently, the frequency converter is not to be installed in environments, where liquids, particles or gases are in the air that would impact and damage the elec- tronics.
Unless the necessary measures are taken to protect the frequency con- verter, there is a risk of stoppages, which reduce the service life of the frequency converter. Derating for ambient temperature The ambient temperature (T AMB,MAX ) is the maximum temperature allowed. The average (T AMB,AVG ) meas- ured over 24 hours, must be at least 5 °C lower. If the frequency converter operates at temperatures above 45 °C, a derating of the rated output current is neces- sary. Liquids can be carried through the air and condense in the frequency converter. In addition, liquids may fa- cilitate galvanic corrosion of components and metal parts.
Steam, oil and brine may cause corrosion of components and metal parts. In these areas, it is rec- ommended to fit units in cabinets. As a minimum, cabinets should be enclosure IP 54. Particles in the air, such as dust particles, may lead to mechanical, electrical and thermal faults on the fre- quency converter. Typical indicators that there are too many particles in the air are dust particles around the frequency converter fan. In very dusty areas, cabinet fitting of units is recommended. As a minimum, cabi- nets should be enclosure IP 54.
Aggressive gases, such as sulphur, nitrogen and chlorine compounds, together with high humidity and temperature, facilitate possible chemical processes on the components of the frequency converter. These chemical processes quickly impact and damage the electronics. In these areas, cabinet fitting with fresh-air circulation in the cabinet is recommended, thereby en- suring that aggressive gases are kept away from the frequency converter. NB! Fitting of frequency converters in aggres- sive environments increases the risk of stoppages, in addition to considerably re- ducing the service life of the unit.
Before the frequency converter is installed, it must be checked whether there are liquids, particles or gases in the air. This can be done by looking at existing in- stallations in the same environment. Typical indicators of harmful airborne liquids are water or oil on metal parts or corrosion of metal parts. Too many dust par- 76 MG.29.A3.02 - VLT ® is a registered Danfoss trademark