ALPHA - Brake Resistors for Large Peak Effects

The increased need for frequency converters for control of speed and position of electro motors has lead to an increased demand for brake resistors. In order to meet this demand, Danotherm Electric A/S has developed a series of stable and mounting-friendly brake resistors for high pulse load.

Brake resistors are used to absorb the excess energy that comes when a system is decelerated. This can involve long steady impulses in relation to lifts or very high and short impulses from e.g. robots.

For All Environments and Requirements
No matter where they are to be used, the brake resistors must be installable in very varied environments, ranging from dry lift shafts to outdoor asphalting machines. Thus, the requirements for the protection rating have been increased particularly in recent years, just as customers are more often asking for various approvements - the UL in particular.

As a total supplier of brake resistor solutions for industrial applications, Danotherm is focused on their products meeting the customers' demands. A consequence of this is a further development of an existing family of brake resistors called ALPHA. This presents new types that meet the requirements of IP65 or NEMA4 and that are also UL Listed as well as CE-marked.

In All Lengths and Density Classes
The ALPHA resistors are constructed with wirewound resistor elements that are fixed in sand or MgO and encircled in aluminium profiles. This construction provides an efficient diversion of the heat from the resistance wires at the same time as it separates the brief, yet strong heating of the wire during the brake impulse itself from the outer surface of the resistor. Furthermore, the fixing of the wire in sand allows for the necessary thermal expansions during the impulses without damaging the construction.

The new ALPHA-resistors CCR, CBR and CBT have larger surfaces in the shape of fins and can be produced up to lengths of 800 mm. The profiles are constructed so the aluminium cast mounting boxes can be mounted on the profiles, which means the required density class can be reached.

CCR, CBR and CBT can be delivered as individual components for resistance (UL Recognized) or as complete brake resistors with connecting boxes in IP65 (UL Listed). The power areas range from 100W to 5kW on average charge and the impulse charges are typically 50 times a second and 10 to 20 times for 10 seconds compared to the average carrying capacity.

Optimum and Well Documented Solutions
In order to find the optimum solution for a given application, Danotherm has developed thermal models that are individual for each resistor. By using theses models Danotherm can assist customers in choosing the most suitable resistors for a given application at the same time as clients can document their projects in advance.

Further information
Area Manager Flemming Thygesen
Tel: +45 36 73 22 22