Product Description:

The SM 25/50-TC is an AC inverter module produced by Bosch Rexroth Indramat for the SM AC Inverters series. This drive interfaces between the plant controller and a three-phase motor, converting a fixed DC bus into variable frequency and voltage output for closed-loop process control. By modulating current and voltage according to external setpoints, the unit regulates motor speed, acceleration, and braking torque in automated machinery. Its electrical ratings position it for medium-power axes that require fast current transients without overshoot. This layout also allows the module to work as a compact power stage in systems that use a centralized DC source.

The inverter operates with a control electronics supply of 24 VDC, delivered through the I/O port so internal logic stays isolated from the power stage. Current feedback is scaled so that 8 V = Imax, which simplifies signal verification with an oscilloscope during setup. The main DC link is stabilized at 520 VDC, providing the energy reservoir for pulse-width modulation and helping the drive maintain torque at rated speed. During short bursts, the power section can deliver 50 A, which supports rapid acceleration of high-inertia loads and brief demand spikes. Command values enter through an analog channel where 10 V = SWmax, allowing a standard ±10 V control signal to cover the full speed range.

Continuous operation is limited to 25 A, a figure that sets the thermal loading of the IGBTs and guides heat sink sizing. To protect the silicon, an alarm is issued once the fin reaches 80 °C, while a separate sensor inside the motor winding trips the drive at 145 °C to help prevent insulation damage. Connections are arranged for straightforward wiring: X1 carries phase conductors, X5 and X6 read resolver or encoder signals, and a service jack outputs diagnostic data to a computer. The shield drain is secured with a Faston plug, and each terminal block clamp is tightened to 3.7 ±0.2 Nm to maintain low contact resistance under vibration.