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Frequency Converter SD4B

Frequency converter SD4B by SIEB & MEYER, the successor of SD2B plus, can be used as a highly dynamic servo amplifier for the operation of rotary and linear low-voltage servo motors as well as for optimized operation of high-speed low-voltage synchronous and asynchronous motors and of IPM motors. On the control side, the SD4B enables the operation up to a rotating field frequency of 4,000 Hz (240,000 rpm), which is a unique feature in the market and allows customers to create new system designs.

Due to this motors can be operated speed-controlled and torque-controlled even from speed zero. The safety function Safe Torque Off (STO) is integrated as standard in the device to allow low-cost realization of the steadily increasing demands towards machine safety. 

In the high-speed range, the SD4B allows sensor-based operation of motors with superimposed synchronization based on 24 V synchronization signals. Thus, several high-speed motors can be operated with angular synchronism via master/slave connection, which is useful in the field of optical systems, for example. The robust speed control also permits high mass inertia ratios between motor and tool of up to 1:100.

Starting in early 2023, the NRTL/CSA certification, which is currently being applied for, enables users to integrate the devices into systems for the US market without additional approvals.


  • Master-Slave-Operation

    Synchronization of several SD4B / motors with superimposed synchronization based on 24 V synchronization signals.

    Autarkic high-precision synchronization of several SD4B frequency converters without external control components.

    Lower system costs.

  • Universal Motor Control

    Sensorless and sensor based operation of low-voltage synchronous and asynchronous motors and of IPM motors.

    Optimal operating mode for a wide variety of system configurations.

    Reduction of the variety of devices.

  • Integrated Logic Voltage Supply

    NRTL/CSA certified.

    Easier integration into machines for the North American market.

    Lower costs, as no additional approvals are necessary.

The Space Marvel

Frequency Converter SD4B comes with an IP20 housing and stands out for its compact design: thanks to its width of only 25 mm, the device requires very little installation space. In addition, the frequency converter is equipped with an internal logic voltage supply - there is no need for an additional external 24 VDC supply. 

The SD4B is equipped with the STO safety function as well as CANopen, Modbus RTU and Modbus TCP as standard. An EtherCAT interface is offered as an option, PROFINET and POWERLINK are in preparation. In addition to the TTL encoder inputs and outputs, five digital inputs/outputs each as well as an Ethernet interface for easy parameterization are available to the users.

The Interfaces of Frequency Converter SD4B

  1. DC supply
  2. EtherCAT (Powerlink and PROFINET in preparation)
  3. Ethernet 100 MBit, Modbus TCP, parameterization, diagnosis and operation
  4. Analog reference value interfaces: +/-10 V
  5. Safety integrated "STO": Restart lock to meet category 4/PL e according to EN ISO 13849-1:2015 and EN 61508:2010 SIL3
  6. 5 digital inputs and 5 digital outputs as well as 24 V DC voltage supply
  7. RS232/485, CAN, CANopen, ModbusTCP interface
  8. Digital motor encoder interface (BiSS-C, EnDAT 2.2, TTL, Hall)
  9. Motor connection

Drive Functions and Safety Functions


Software for Initial Operation and Parameterization: drivemaster4

The parameterization, simulation and diagnostic software drivemaster4 enables the user to commission drive systems easily and quickly. With the integrated simulation tool Motor Analyzer, the user can already prove at the time of system design that the desired system characteristics in terms of operating points and harmonics can be realized. The basis for this is suitable electrical motor data.


  • Electrical operating points
  • Influence of PWM frequency/converter topology
  • FFT analysis including THDi/THDu calculation
  • Export of simulation data


  • Parameterization of the motor data/interfaces
  • Optimization by means of oscilloscope
  • Commissioning tool


  • Data logger
  • Real-time clock
  • Error memory
  • Operating hours counter

Technical Specifications of Frequency Converter SD4B

Device type Rated power1) Rated current Peak current/time Max. output voltage1) HxWxD (mm) Weight Cooling
Device with housing (SD4B) - 1 x 24...80 VDC supply voltage
0SD4BB1D1Pxxxx 2) 940 VA 10 Arms 12 Arms/10 s 3 x 55 VAC 165 x 120 x 25 0.55 kg Air

1) Rated power and max. output voltage for mains voltage/supply voltage (in italic)
2) NRTL/CSA certified (starting early 2023)


  • High-speed spindles are the key components of a machine tool. Only when operated in an optimal way, the desired machining accuracy, productivity and service life of the whole machine is guaranteed. 


  • For dressing applications, it is essential to keep the spindle temperature low: a temperature increase in the spindle causes a longitudinal growth and therefore a shift of the tool position. 


  • Small CAD/CAM routing machines are used, for example, in dental laboratories for jewelry making or engraving works as well as for producing advertising displays. 


  • Polygon scanners are based on special optics and operate, for example, sorting machines. Up to now, manufacturers had to install encoders to run these scanners with a high speed stability.

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