LTI Drives BR-090.03.540.UR.H38 Braking Resistor E232497 ALW 70 750VDC 300W
The LTI Drives BR-090.03.540.UR.H38 Braking Resistor E232497 ALW 70 750VDC 300W is a braking resistor used in industrial drive systems. It absorbs electrical energy that is generated when a motor decelerates or when a load drives the motor. This energy would otherwise increase the DC link voltage in the drive. The braking resistor converts the energy into heat and helps keep the drive within safe operating limits.
The model code contains important technical information. BR identifies the braking resistor family. The 090 value relates to the mechanical size or resistance class. The 03 and 540 values provide additional rating and voltage information. UR and H38 indicate design and cooling features. E232497 is an identification number. ALW 70, 750VDC, and 300W describe the operating voltage and power dissipation class. These details help users match the resistor to the drive and braking duty cycle.
Function in Drive Systems
When a servo motor or inverter drive brakes a high inertia load, energy flows back into the drive DC link. If this energy is too high, the DC link voltage rises and the drive may trip. A braking resistor provides a controlled path for this energy. The drive activates a brake chopper, which connects the resistor to the DC link for short periods. The resistor heats up and dissipates the energy as heat.
Braking resistors are used in applications with frequent starts and stops, vertical axes, unwinding systems, and high inertia loads. Correct resistor selection depends on peak braking power, continuous braking power, duty cycle, and resistance value. The resistance must match the drive brake chopper specification. The power rating must be sufficient for the thermal load over the machine cycle.
Construction and Cooling
The BR-090.03.540.UR.H38 is designed for panel or machine mounting. It includes a resistive element and a housing that supports heat dissipation. The H38 marking relates to the cooling and mounting design. The resistor must be installed with adequate clearance for air circulation. Surface temperature can become very high during braking, so it must be mounted away from combustible materials and protected against accidental contact.
Wiring must use suitable high temperature cables and protective devices. The resistor circuit should be separated from signal cables. The protective earth connection must be secure. The drive parameters for brake chopper operation must be set correctly to avoid overload.
Installation
Mount the resistor on a stable surface inside a ventilated cabinet or in a protected area. Follow the minimum clearance requirements. Do not cover the cooling openings. Connect the resistor to the drive brake chopper terminals according to the drive manual. Use the specified cable cross section. Check terminal tightness. Ensure that the resistor is not installed near heat sensitive components.
Before power is applied, verify the resistance value and wiring. Check that the drive brake chopper is enabled and configured. Test braking at low load first. Monitor DC link voltage and resistor temperature during the test. Increase the duty cycle gradually while checking thermal behavior.
Commissioning and Operation
During commissioning, the drive must know the resistor resistance and power rating. The brake chopper threshold and duty cycle limits must be set. The machine cycle should be tested to confirm that the resistor does not overheat. If the resistor becomes too hot, the duty cycle may be too high or the resistance value may be incorrect. In some systems, a thermal switch or temperature sensor is used to protect the resistor. This signal should be connected to the drive or machine controller.
During operation, the resistor may produce heat and a slight odor when first used. This is normal for some materials, but overheating, smoke, or discoloration indicates a problem. The drive fault history should be checked if DC link overvoltage faults occur.
Maintenance
Regular maintenance includes checking terminals, mounting, and cooling paths. Remove dust and dirt from the resistor surface and cabinet filters. Inspect cables for heat damage. Measure resistance if a fault is suspected. Replace the resistor if the element is broken or the housing is damaged. Always disconnect power and wait for discharge before servicing.
In summary, the LTI Drives BR-090.03.540.UR.H38 Braking Resistor E232497 ALW 70 750VDC 300W provides reliable energy dissipation for drive braking. Correct selection, installation, and thermal management help protect the drive and maintain stable machine operation.
