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The Emerson SP3401 is a high-performance AC drive in the Unidrive SP series, developed for variable-speed motor control in industrial machinery. It supports open-loop and closed-loop motor control configurations, allowing the drive to be applied to induction motor systems and compatible servo applications according to the selected control mode and feedback arrangement.
The SP3401 operates with a three-phase 380–480 V AC supply. Its rated output current is 32 A in Heavy Duty operation and 35 A in Normal Duty operation, making it suitable for industrial equipment requiring controlled acceleration, speed regulation and coordinated motor operation. Typical applications include pumps, fans, conveyors, extruders, winding equipment and production machinery.
The drive combines motor-control functions with configurable inputs and outputs, serial communication and expansion slots for optional interface modules. A built-in PLC function supports drive-related automation tasks, while Smartcard functionality allows supported parameter configurations and programs to be stored and transferred. These features help engineers adapt the drive to different machine-control requirements without changing the basic drive platform.
| Parameter | Specification |
|---|---|
| Manufacturer | Emerson / Control Techniques |
| Model | SP3401 |
| Product Series | Unidrive SP |
| Product Type | Universal AC and Servo Drive |
| Drive Configuration | Panel-Mount Variable-Speed Drive |
| Input Voltage | 380–480 V AC |
| Input Phase | Three-phase |
| Input Frequency | 48–65 Hz |
| Normal Duty Output Power | 18.5 kW |
| Heavy Duty Output Power | 15 kW |
| Normal Duty Output Current | 35 A |
| Heavy Duty Output Current | 32 A |
| Control Modes | Open-loop V/Hz, open-loop vector, rotor flux control, closed-loop vector and compatible servo control |
| Serial Communication | Built-in RS-485, Modbus RTU |
| Analog Inputs | 3 |
| Analog Outputs | 2 |
| Digital Inputs | 6 standard digital inputs, with configurable functions depending on setup |
| Digital Outputs | 3 |
| Relay Outputs | 1 |
| Expansion Slots | 3 option-module slots |
| Programmable Logic | Built-in drive PLC function |
| Enclosure Protection | IP20 |
| Cooling Method | Forced convection |
| Dimensions | 368 × 250 × 260 mm |
| Weight | 3.5 kg |
The SP3401 converts incoming three-phase AC power into a controlled electrical output for the connected motor. Its power electronics regulate the output voltage and frequency according to the configured control mode, motor data and speed reference.
In open-loop V/Hz or vector operation, the drive adjusts motor output according to the selected control strategy and the requested operating speed. Closed-loop vector operation uses compatible feedback equipment when required to improve control of motor speed and torque. Servo applications require the appropriate motor, feedback arrangement and configuration.
For example, on a conveyor line, a PLC can send a speed reference and run command to the SP3401. The drive regulates motor operation according to the reference and configured acceleration and deceleration settings. Status signals and fault information can be returned to the controller, allowing the wider machine-control system to coordinate the conveyor with upstream and downstream equipment.
The built-in PLC function can handle supported local logic, while serial communication and optional modules provide additional integration possibilities. Actual behavior depends on motor characteristics, drive parameters, feedback devices and the application configuration.
The SP3401 serves as the motor-power conversion and speed-control component in an industrial automation system. It receives operating commands and references from a controller or configured local control logic, then regulates the electrical output supplied to the motor.
| System Component | Function | Relationship to the SP3401 |
|---|---|---|
| SP3401 AC Drive | Regulates motor voltage, frequency and operating behavior | Controls the connected motor |
| Three-Phase AC Supply | Supplies electrical power | Provides the drive input |
| Induction Motor | Converts electrical energy into mechanical motion | Receives the controlled drive output |
| PLC or Machine Controller | Executes machine sequencing and interlocks | Sends commands and speed references |
| Encoder or Feedback Device | Measures motor position or speed where required | Supplies feedback for supported closed-loop configurations |
| RS-485 Communication Network | Exchanges serial data | Connects the drive to compatible control equipment |
| Analog Reference Source | Provides a configured speed or process reference | Supplies an input for drive regulation |
| Digital Control Signals | Carry run, stop, enable and other configured commands | Control drive operation |
| Braking Resistor | Dissipates regenerated energy where required by the installation | Supports applications requiring additional braking capability |
| Option Module | Adds supported communication, feedback, I/O or automation functions | Extends the drive configuration |
| Motor Protection and Isolation Devices | Support electrical protection and safe isolation | Form part of the surrounding installation |
The actual architecture depends on the motor type, selected control mode, feedback requirements and machine safety design.
| Application | Typical Equipment | Role of the SP3401 |
|---|---|---|
| Conveyor Systems | Production conveyors and material-transfer lines | Regulates motor speed to coordinate material movement |
| Pumping Systems | Industrial process and utility pumps | Adjusts motor speed according to process demand |
| Industrial Fans | Ventilation and process-air equipment | Controls airflow through variable-speed operation |
| Extrusion Machinery | Plastic and material-processing equipment | Regulates drive speed according to production requirements |
| Winding Equipment | Web handling and material winding systems | Supports configured speed and feedback control |
| Packaging Machinery | Automated packaging and conveying equipment | Coordinates motor speed with machine sequences |
| Hoists and Material Handling | Compatible lifting and movement equipment | Supports configured motor control when the drive and system ratings are suitable |
| Printing Machinery | Web-fed printing and material transport systems | Regulates motor operation within the configured control arrangement |
| General Manufacturing | Industrial machines with variable-speed motors | Provides adjustable speed and motor-control functions |
| Component | Function | Relationship to the SP3401 |
|---|---|---|
| Unidrive SP Keypad | Provides local parameter access and operating status | Supports local setup and monitoring when compatible |
| Smartcard | Stores supported drive parameters and programs | Assists with configuration transfer and backup |
| Encoder Feedback Module | Interfaces with compatible motor feedback devices | Supports applicable closed-loop control configurations |
| Communication Option Module | Adds supported industrial communication interfaces | Connects the drive to compatible automation networks |
| I/O Option Module | Adds supported input and output functions | Extends signal-handling capabilities |
| Braking Resistor | Dissipates braking energy where required | Supports applications with demanding deceleration requirements |
| Three-Phase Induction Motor | Converts drive output into mechanical motion | Serves as the controlled motor load |
| PLC | Coordinates machine logic and interlocks | Sends operating commands and receives status information |
| Motor Isolation Device | Provides electrical isolation for servicing | Supports safe maintenance procedures |
| Control Transformer or DC Power Supply | Supplies power to associated control circuits where required | Supports the wider drive-control installation |
| Model | Product Type | Relationship | Selection Consideration |
|---|---|---|---|
| Emerson SP3401 | Unidrive SP Universal AC and Servo Drive | Main product | 380–480 V AC drive with 32 A Heavy Duty and 35 A Normal Duty output ratings |
| Emerson SP3402 | Unidrive SP Universal AC and Servo Drive | Same frame family | Higher output-current model; verify motor and load requirements |
| Emerson SP3403 | Unidrive SP Universal AC and Servo Drive | Same frame family | Higher-rated alternative for compatible applications |
| Emerson SP2401 | Unidrive SP Universal AC and Servo Drive | Smaller frame family | Alternative where the required power rating and installation arrangement permit |
| Emerson SP2402 | Unidrive SP Universal AC and Servo Drive | Smaller frame family | Compare current ratings and duty requirements before selection |
| Emerson SP2403 | Unidrive SP Universal AC and Servo Drive | Smaller frame family | Evaluate against the motor rating and required operating mode |
Related models are not automatically interchangeable. Selection must account for supply voltage, motor current, duty rating, control mode, feedback requirements and installed option modules.
The drive has different output ratings for the two duty classifications. The SP3401 is rated at 35 A and 18.5 kW in Normal Duty operation, compared with 32 A and 15 kW in Heavy Duty operation. The correct classification depends on the motor load and application requirements.
Yes. The Unidrive SP supports open-loop control modes that do not require encoder feedback. Closed-loop operation requires the appropriate feedback arrangement and configuration.
The drive includes a two-wire RS-485 serial interface and supports Modbus RTU communication. Additional communication protocols can be supported through compatible option modules.
Compare the supply voltage, motor current, Normal Duty and Heavy Duty ratings, control mode, feedback requirements and installed option modules. Also verify the control wiring and parameter configuration before commissioning the replacement.