RZM Motor Filters

RZM Motor Filters are Bosch Rexroth RD500 output-side filters used between the frequency converter and motor to limit voltage stress created by pulse-converter operation and extended motor-cable runs. Their main function is to reduce transient overvoltage at the motor terminals while also lowering cable leakage current and improving EMC performance in the drive installation. The series covers 3-phase 380–400 V and 3-phase 500 V applications, with operating limits that depend on voltage class, output frequency, cable type, and total motor-cable length. In 380–400 V systems, cable lengths can reach up to 150 m at 200 Hz or 300 m at 100 Hz, while 500 V systems allow up to 120 m at 200 Hz or 200 m at 100 Hz; shielded cable installations reduce these permitted lengths by 50%. RZM filters are available across a wide current range, from smaller 8 A and 10 A models to larger 350 A units, with nominal current values defined at 4 kHz and 8 kHz pulse frequencies. Wiring is arranged with U1/V1/W1 as the filter input from the converter and U2/V2/W2 as the filtered output to the motor.