Product Details:

The SEW BW039-012 braking resistor is a wire-wound dynamic braking resistor specially developed for SEW MOVIDRIVE MDX61B, MD60A and MOVITRAC B series variable frequency drives and servo drives. Its nominal resistance value is 39 ohms and the continuous braking power is 1.2kW under 100% cyclic duration factor. Although its continuous power rating is relatively low compared with large grid resistors, it still has reliable short-time overload capacity and can handle instantaneous regenerative peak energy during frequent deceleration and stop actions of light and medium loads. This base model BW039-012 does not integrate a built-in thermal contact switch. According to machine safety design specifications, users need to add an external thermal protection relay in the wiring circuit to realize independent over-temperature interlock, so as to avoid permanent thermal damage of the resistance core under long-time continuous braking cycles.

The internal part adopts high-quality alloy resistance wire winding structure and high-temperature inorganic insulating filler. It can maintain stable resistance value within the tolerance range of ±10% under repeated thermal shock and instantaneous current impact, and has good anti-aging performance under long-term intermittent braking cycles. The compact wire resistor structure is designed for simple installation inside the electrical cabinet, and it is equipped with standard power terminals for direct wiring to the braking chopper terminals of the matched SEW drive. The drive’s built-in monitoring logic can detect open circuit and short circuit faults of the braking loop. If the resistance winding burns open, suffers short-circuit damage, or the connecting cable is aged and disconnected, the drive will lose the channel for regenerative energy dissipation. The DC bus voltage will rise sharply during deceleration, the equipment cannot realize fast stop and load descending functions normally, and the control system will trigger overvoltage fault alarm and safety interlock stop.

This braking resistor adopts IP20 protection grade. The working ambient temperature range is 0℃ to 55℃, and the storage temperature range is -20℃ to 70℃. The surface temperature of the resistor shell will rise obviously during braking operation. Enough heat dissipation clearance must be reserved around the installation position. Cables, wire ducts and other electrical components cannot cover the heat dissipation area, otherwise heat accumulation will be caused and the service life of the resistor will be shortened. When matching this resistor with the SEW drive, it is necessary to strictly check the minimum braking resistance limit of the internal braking chopper to prevent the IGBT braking unit from being burned out due to the excessively low resistance value.

This SEW BW039-012 braking resistor is widely used as maintenance replacement spare parts for light-duty material conveyors, small packaging auxiliary machines, printing auxiliary equipment, small lifting positioning axes and other automation equipment that require low-power intermittent braking. Most spare parts circulating on the global industrial spare parts market are fully tested refurbished stock. Before installation, technicians need to check whether the shell is deformed, burnt or cracked, and use a multimeter to measure the resistance value to confirm that it is within the standard tolerance range. After wiring, complete the jog test and high-speed deceleration test to verify the stability of DC bus voltage during braking. Regular cleaning of dust accumulated on the resistor surface and inspection of terminal tightness can effectively reduce the probability of intermittent faults and extend the service life of the braking resistor and the matched drive system.