Bosch RD500 Indramat Servo Drive System (RD51.2-4B-007-L-NN-FW + RZE01.2-5-007)
Product Overview
The Bosch RD500 series, also known as Indramat, is a family of high-performance analog servo drives widely used in industrial motion control. This listing includes two components: the RD51.2-4B-007-L-NN-FW power unit (drive) and the RZE01.2-5-007 regulator card. Together, they form a complete servo drive system for controlling AC permanent magnet synchronous motors (Indramat MKD, MHD, etc.). The system accepts ±10V analog torque/speed commands from a motion controller or PLC and provides resolver feedback for precise positioning.
RD51.2-4B-007-L-NN-FW Power Unit Specifications
Model: RD51.2-4B-007-L-NN-FW
Type: Power amplifier section of RD500 drive
Supply Voltage: 3-phase 230-480 VAC (line rectified to DC bus)
Continuous Output Current: 24 A rms
Peak Output Current (2s): 48 A rms
Internal Bus Capacitance: Large (for high peak torque capability)
Control Supply: 24 VDC (via RZE01.2)
Cooling: Fan-forced internal
Dimensions: Module format fits in 19" rack or panel mount
RZE01.2-5-007 Regulator Card
Model: RZE01.2-5-007
Type: Servo regulator / control card
Feedback Interface: Resolver (1.8Vrms excitation)
Command Input: ±10V analog (torque, speed, or position loop), plus incremental encoder input for master following
I/O: 4 digital inputs (24V), 2 digital outputs (relay), 2 analog monitor outputs
Parameter Storage: EEPROM
Adjustments: Potentiometers for gain and offset, DIP switches for basic config
Control Architecture
The RD51.2-4B power unit supplies the high current to the motor, while the RZE01.2 card handles all signal processing, current loop, and resolver decoding. The system can operate in torque mode (current command) or speed mode (velocity command). An optional incremental encoder input allows electronic gearing to a master axis. The resolver feedback provides absolute rotor position for high starting torque at zero speed.
Integration with PLC and Motion Controllers
Because the RD500 is an analog drive, a PLC or CNC typically sends a ±10V analog signal (via an analog output module) to the RZE01.2’s command input. The drive’s digital I/O can be used for enable, reset, and fault monitoring. For multi-axis systems, up to 8 drives can be connected to a single power supply module (e.g., RD51.1-6B-011).
Tuning and Setup
The drive is tuned using potentiometers on the RZE01.2: proportional gain (KP), integral time (TN), and current limit. More advanced parameters (field weakening, internal offset) can be set via an optional serial interface (using Indramat’s COM software). The resolver excitation frequency and gain are configured via DIP switches.
Applications
Machine tool feed axes (milling, lathe)
Printing press register controls
Industrial robots (AC servo drives)
Dynamometer and test stands
Common Failure and Troubleshooting
Typical issues include resolver cable breakage (drive trips with “Resover fault”), blown IGBTs (shorted output), or power supply failure. The drive’s LED indicator codes can be cross-referenced with the Indramat manual. The RZE01.2 card itself is field-replaceable without removing the power unit.
Conclusion
The Bosch RD500 Indramat RD51.2-4B-007-L-NN-FW with RZE01.2-5-007 regulator forms a rugged, high-current analog servo drive solution. Its resolver feedback and peak current capability make it suitable for demanding positioning and speed control tasks in heavy machinery.





