RZW03.1-004-025

Product Description:

Bosch Rexroth Indramat manufactured the RZW03.1-004-025. The power class is the first filtering parameter for engineers to choose resistors for specific energy dissipation needs, even if Bosch Rexroth’s classification is proprietary. Under normal braking loads this number helps to predict thermal and electrical performance. Resistors in this class are designed to absorb and dissipate mechanical energy from a decelerating motor in regenerative braking applications to prevent damage to the drive or associated components. In high-magnitude or repeated braking events, the power class gives a baseline of the component’s thermal endurance. The RZW03.1-004-025’s minimum connectable resistance of 30 W is a key feature. Instead of a resistance value in ohms, this is probably the lowest power that can be dissipated without thermal instability, even if it’s given in watts. Since the resistor must operate below certain temperature thresholds to prevent overheating, the differentiation is important.

The last load that can be applied while still having sufficient heat dissipation and safe current flow is defined by this value. Below this limit, the operation may cause excessive current draw, thermal stress or even failure. From a design perspective this number is a boundary condition to ensure the resistor operates within specified electrical and thermal margins even under high braking torque. It shows the mechanical construction’s ability to disperse and transmit heat as well as the rating of the internal resistive material. Advanced thermal design, probably with large surface-area fin structures, active airflow and thermally robust materials, is indicated by the ability to withstand 3.5 kW in both cases. It means the resistor can handle prolonged periods of moderate braking energy as well as short high intensity pulses without going beyond acceptable temperature limits. This kind of thermal homogeneity is rare and means either very effective convective cooling systems or exceptional thermal conductivity.

It’s also backed up by the steady-state resistance of 47 Ω for both duty cycles, which means minimal resistive drift under thermal load, which is important for braking torque in servo or spindle motor control. A built-in axial ventilator for 3-phase, 400V, 50Hz operation helps with heat management. Axial airflow accelerates thermal dissipation and provides cooling along the entire length of the resistor. The ventilation system keeps thermal homeostasis active with air current monitoring, probably via a wind vane relay. The monitoring system will sound an alarm or shut down the drive system if airflow falls below a certain level to prevent overheating and protect the resistor and the associated motor drive hardware.