These braking resistors are insulated and can easily be mounted in compact constructions. They are specially constructed for high pulse loads compared to the average load. The nominal load can be improved by forced air cooling or by mounting the resistors on a heat sink. The resistor elements are wirewound on mica support sheets. Lower ohmic values are made with helix wound elements mounted in ceramic support. The outer housing is an aluminium profile insulated with micanite sheets on all inner surfaces. The resistor elements are fixed symmetrically in the profile by the mica construction. This ensures a symmetric expansion of the resistors and maximum stability to high load impulses. The aluminium profile with the fixed resistor element is filled with quartz sand. This ensures a minimum change of the resistor surface temperature even if the resistor element reaches its maximum temperature during a pulse load.

Small size

The Alpha range of resistors from Danotherm consist of fully welded wirewound resistors, mounted in silica sand, insulated with Micanite and mounted in an anodised aluminium house. The base material is high temperature Micanite which is long time stable at +700°C and short time resistant up to +1000°C. The construction has high resistance to temperature changes. These braking resistors comply with IP50 giving electrical and thermal protection. Danotherm has developed thermal simulation corresponding to all resistor types and resistor values. By using these models, Danotherm were able to calculate the temperature rises in the resistor wire and on the surface for all possible load applications.