The Bautz SMD 101/120 is a compact, high-performance analog servo drive (also referred to as a servo amplifier) designed for the precise control of permanent magnet DC servo motors. Originally manufactured by Bautz (now part of the Kollmorgen / Danaher Motion group), the SMD series is a legacy powerhouse in the field of industrial automation. It is engineered to provide high-bandwidth velocity or torque control, making it a reliable choice for machine tool axes, robotics, and high-speed positioning systems.

Technical Description & Parameters

The SMD 101/120 utilizes a Pulse Width Modulation (PWM) power stage to provide efficient and smooth power delivery to the motor.

• Model Number: SMD 101/120
• Drive Type: 4-Quadrant DC Servo Amplifier
• Rated Current: 10 Amperes (Continuous)
• Peak Current: 20 Amperes (for acceleration/short cycles)
• DC Bus Voltage: 120V DC (Nominal)
• Input Voltage: Typically 100V AC to 120V AC (via external transformer/rectifier)
• Control Interface: Analog ±10V DC Command Signal
• Feedback Options: DC Tachometer (Standard) or Encoder (via optional interface card)
• Protection: Overvoltage, Short-Circuit, and Thermal Overtemperature monitoring.

 

Product Technical Description

The SMD 101/120 is an “Analog” drive, meaning it does not require complex software programming to commission. Instead, it relies on a series of onboard potentiometers (trimpots) to tune the PID (Proportional-Integral-Derivative) control loop. The 4-quadrant design allows the drive to both drive and brake the motor in both directions, which is essential for vertical axes or high-inertia loads that require active deceleration. The modular plug-in design allows for quick replacement in the field without rewiring the entire control cabinet.

 

Product Datasheet Essentials

The “101/120” designation signifies its current-to-voltage capability. It features a robust aluminum heat sink for natural convection cooling, though many installations utilize external fans for high-duty cycle applications. The drive includes diagnostic LEDs on the front panel to indicate “Ready,” “Fault,” and “Current Limit” statuses. It is designed to be DIN-rail or panel-mounted within a protected electrical enclosure (IP20 rating).

 

Country of Origin

Germany (Bautz / Kollmorgen)

 

Application Fields

The Bautz SMD series is a staple in various precision engineering sectors:

• Textile Machinery: Managing high-speed spindle and loom controls.
• Packaging Equipment: Synchronizing film feed and cutting mechanisms.
• Lab Automation: Powering small-scale robotic arms and liquid handlers.
• Legacy CNCs: Serving as the axis drive for older milling and grinding machines.

 

Product Usage Instructions

1. Mounting: Install the drive vertically to allow for optimal airflow through the cooling fins.
2. Power Connections: Connect the 120V DC bus to the power terminals. Ensure a proper fuse is installed on the DC supply line to protect the power transistors.
3. Signal Wiring: Connect the ±10V analog command from your CNC or PLC to the signal input terminals. Ensure shielded cables are used to prevent electrical noise.
4. Tuning: Use the “Gain,” “Offset,” and “Current Limit” potentiometers to match the drive’s response to the specific motor and load inertia.
5. Grounding: Verify that the drive chassis and the motor frame are securely connected to a common star-point ground to eliminate ground loops.

 

Common Questions & Answers (Q&A)

Q: Can I use this drive with a brushless AC motor? A: No. The SMD 101/120 is designed specifically for Brushed DC servo motors. For brushless motors, you would need the Bautz BSM or Kollmorgen AKD series.

Q: My drive is showing a “Fault” LED; what should I check first? A: First, check the motor for a short circuit or worn-out brushes. Next, verify that the DC bus voltage is within the 100-130V range. If the fault persists, it may indicate a failure in the internal power bridge.

Q: Is there a modern replacement for the SMD 101/120? A: Since this is a legacy product, Kollmorgen often recommends a modern digital drive with an analog input interface. However, keeping the original drive is often easier to avoid rewiring and retuning the entire control system.

 

Explore More Motion Control Hardware

For technical support and to source the SMD 101/120 along with other Bautz and Kollmorgen spare parts, visit our online technical catalog.

 

Recommended Similar Models

1. SMD 102/120 – A higher-current version (20A continuous) for larger DC motors.
2. SMD 101/60 – A lower voltage (60V DC) version for smaller servo applications.
3. Kollmorgen Servostar – A modern digital successor for comprehensive motion control.
4. Bautz E series – Legacy DC motors frequently paired with the SMD drive.
5. Bautz W series – High-torque DC servo motors compatible with this amplifier.