Product Overview

The Emerson DST1404 Digitax ST Servo Drive is an AC servo drive in the Digitax ST family, intended for controlling servo motors in industrial motion applications. Its 5.9 A rated output current and 17.7 A peak output current place it above the DST1401, DST1402 and DST1403 in the same 380–480 V drive range.

The DST1404 is suitable for servo axes that require higher current capacity during acceleration, rapid repositioning or changes in mechanical load. Typical applications include automated assembly machinery, packaging lines, indexing systems and material-handling equipment, where the motor must follow a programmed motion profile while remaining coordinated with other machine operations.

In an indexing machine, for example, a motor may need to accelerate a loaded turntable, bring it to a precise stopping position and hold the required operating state while another process takes place. The drive regulates the motor’s electrical output, while the motion controller determines the movement sequence. Selecting the correct current rating requires consideration of the motor specifications, load inertia, acceleration time and operating cycle.

The DST1404 uses a three-phase 380–480 V AC supply and an internal fan cooling arrangement. When installing it in an existing Digitax ST system, engineers should verify the complete drive variant, motor feedback compatibility, control interface and braking requirements. Sharing the same product family does not guarantee that two drive models can be exchanged without checking their electrical ratings and configuration.

Technical Specifications

Product Features

• Three-phase AC input: Operates from the specified 380–480 V AC supply class.
• 5.9 A rated output current: Supports compatible servo motors with continuous current requirements within the drive’s rating.
• 17.7 A peak output current: Accommodates short-duration current demand within the permitted operating limits.
• Digitax ST platform: Integrates into compatible servo motion-control systems using the same drive family.
• Motor feedback control: Supports closed-loop operation when paired with a compatible feedback device and correctly configured control system.
• Internal fan cooling: Removes heat generated during drive operation.
• Configurable motor parameters: Allows motor data, current limits and control settings to be matched to the application.
• Optional interface capability: The Digitax ST range supports additional interface modules and control functions, depending on the installed drive variant.

Working Principle

The DST1404 converts incoming three-phase AC power into controlled electrical output for a compatible servo motor. It regulates motor current according to the selected operating mode and commands received from the machine’s motion-control system.

During acceleration, the drive supplies the current needed to generate motor torque against the combined inertia and resistance of the mechanical load. As the axis approaches its target speed or position, the control loop adjusts the output to follow the commanded motion profile. During deceleration, the drive manages the motor response and regenerative energy according to the configured braking arrangement.

Consider a packaging line where a loaded transfer mechanism must move rapidly between two stations. The motor may require substantial current during acceleration, followed by controlled deceleration to prevent excessive mechanical impact. The DST1404’s current ratings help determine whether it can meet the required motion profile, but actual performance also depends on the motor, feedback configuration and mechanical system.

The 17.7 A peak rating is intended for permitted short-duration demands, not continuous operation. Drive selection must account for overload duration, operating frequency, thermal conditions and the motor’s current requirements. The drive executes the configured motor-control function; the controller remains responsible for coordinating the axis with the wider machine sequence.

Role in a Digitax ST Servo Motion Control System

The DST1404 acts as the power-control stage between the electrical supply and the servo motor. It receives motion commands, regulates motor output and uses compatible feedback signals to control the motor’s response.

Three-Phase AC Supply → DST1404 Servo Drive → Servo Motor → Mechanical Axis

Motion Controller → Command Interface → DST1404 → Motor Feedback and Control Loop

Industrial Applications

Installation and Maintenance

1. Verify the drive reference: Confirm that DST1404 matches the required voltage class, current rating and control configuration.
2. Check the incoming supply: Verify that the available three-phase AC supply falls within the specified 380–480 V range.
3. Match the motor rating: Compare the motor’s continuous and peak current requirements with the drive’s ratings and permitted overload characteristics.
4. Isolate the equipment: Follow the approved electrical isolation procedure and allow the specified DC-bus discharge time before handling the drive.
5. Inspect cabinet ventilation: Ensure that the internal fan has adequate airflow and that the mounting arrangement meets the installation requirements.
6. Examine the power terminals: Check the incoming supply, motor output and protective earth connections for damage or loose terminations.
7. Verify feedback wiring: Confirm that the motor feedback device, cable and drive interface are compatible.
8. Check motor parameters: Verify the motor data, control mode, current limits and feedback settings before enabling the drive.
9. Review braking requirements: Determine whether the application’s inertia and stopping cycle require a braking resistor or another approved energy-management arrangement.
10. Inspect control wiring: Check command signals, enable circuits, interlocks and any installed option modules.
11. Commission the axis: Test motor direction, feedback response, acceleration, deceleration and positioning under controlled conditions.
12. Record service information: Document the drive reference, motor configuration, parameter settings, fault history and commissioning results.

Compatible System Components

Recommended Related Models

Key Advantages

• Operates from a three-phase 380–480 V AC supply.
• Provides 5.9 A rated output current and 17.7 A peak output current.
• Supports servo motor control with compatible feedback equipment.
• Uses internal fan cooling.
• Fits suitable installations using the Digitax ST Frame Size 1 configuration.

Technical FAQs

How does the DST1404 differ from the DST1403?

The DST1404 has a rated output current of 5.9 A and a peak output current of 17.7 A, compared with 4.0 A and 12.0 A for the DST1403. The appropriate model depends on the motor’s current demand, required acceleration and operating duty.

What should be considered when using the DST1404 for a high-inertia load?

Evaluate the load inertia, acceleration and deceleration times, stopping frequency and motor current requirements. The drive must remain within its continuous and permitted peak operating limits, and the braking arrangement must be suitable for the regenerative energy generated during deceleration.

Can the DST1404 replace a lower-current Digitax ST drive without changing the motor?

Not automatically. The supply voltage, motor ratings, feedback interface, control variant, wiring and parameter configuration must all be checked. A higher drive current rating alone does not establish full system compatibility.

What could cause the DST1404 to overheat during normal operation?

Possible causes include inadequate cabinet airflow, an obstructed cooling fan, high ambient temperature, excessive motor current or a duty cycle beyond the intended operating limits. Review the installation conditions and recorded operating data before replacing the drive.