Product Overview

The Emerson SPMD1422 Unidrive SPM Inverter Module is a high-power inverter module in the Unidrive SPM range. It converts DC-bus power into a controlled three-phase AC output for industrial motors. Unlike the SPMC2402 controlled rectifier, which supplies the DC bus from an AC source, the SPMD1422 performs the inverter stage that drives the motor.

The SPMD1422 is intended for 400 V-class installations, with a nominal supply range of 380–480 V AC applying to the associated drive system. The module is rated for heavy-duty applications with a typical motor power of 110 kW at 400 V. The appropriate operating rating depends on the selected duty, supply conditions, installation arrangement and motor requirements.

In a large production facility, several motors may need to operate at different speeds while sharing a common DC-bus architecture. For example, a material-processing line may use separate drives for a main conveyor, feed rollers and a processing mechanism. A modular arrangement allows the inverter stages to be selected according to the individual motor loads while drawing power from a compatible rectifier and DC-bus system.

The SPMD1422 can be installed directly with a compatible rectifier module in a docked arrangement or separately in an undocked configuration. This distinction matters because the installation arrangement affects cooling and available drive ratings. The rectifier, input line reactor, DC-bus connections, protection and any required output-sharing components must be selected as part of the complete drive system.

Technical Specifications

Product Features

• High-power inverter stage: Converts DC-bus power into controlled AC output for a compatible motor.
• 400 V-class operation: Supports drive systems built around the corresponding three-phase supply and rectifier configuration.
• Heavy-duty motor rating: Supports applications around the 110 kW motor-power class at 400 V, subject to operating conditions.
• Modular drive architecture: Allows the inverter to be combined with compatible Unidrive SPM rectifier equipment.
• Docked or undocked installation: Supports different cabinet arrangements, with ratings and cooling requirements checked for the selected configuration.
• Motor control capability: Supports configured motor-control modes and the feedback arrangements appropriate to the application.
• Shared DC-bus integration: Allows compatible inverter modules to operate within a common power architecture.
• System expansion: Supports multi-inverter configurations when the rectifier, bus connections, current ratings and required sharing components are properly matched.

Working Principle

The SPMD1422 receives DC power from the rectifier and DC-bus assembly. Its inverter power stage switches the DC supply to produce a controlled three-phase output for the connected motor. The output voltage and frequency are adjusted according to the configured drive control and motor operating requirements.

During acceleration, the inverter increases the motor output to develop the torque needed to move the load. As the motor approaches its commanded speed, the drive adjusts its output to maintain the requested operating condition. When the load decelerates, energy may flow back toward the DC bus, so the complete installation must provide an appropriate method of handling regenerative energy.

Consider a large conveyor system carrying material through several processing stages. The motor must maintain the required speed as the material load changes, while stopping and restarting may place additional demands on the drive. The SPMD1422 controls its connected motor, while the upstream rectifier and shared DC bus supply the power required by the inverter.

The inverter’s usable output rating depends on factors such as the selected duty, supply voltage, switching frequency, cooling conditions and installation arrangement. Docked and undocked configurations can have different ratings, so the module should be evaluated in its actual cabinet layout rather than by its model number alone.

Role in a Unidrive SPM Modular Drive System

The SPMD1422 is the motor-side power-conversion stage in a modular drive architecture. A compatible rectifier establishes the DC supply, and the inverter converts that supply into the output needed by its connected motor.

Three-Phase AC Supply → Input Line Reactor → Compatible SPMC/U Rectifier → DC Bus → SPMD1422 Inverter → Motor

Industrial Applications

Installation and Maintenance

1. Verify the module reference: Confirm that SPMD1422 matches the required voltage class, duty rating and inverter configuration.
2. Check the supply architecture: Verify that the upstream rectifier and DC-bus arrangement are suitable for the 400 V-class drive system.
3. Confirm motor sizing: Compare the motor’s rated current, power and operating duty with the inverter’s applicable ratings.
4. Isolate the power system: Disconnect the incoming supply, isolate the DC bus and verify that stored energy has discharged before servicing.
5. Determine the mounting arrangement: Establish whether the inverter will be docked to the rectifier or mounted separately, then apply the corresponding installation and rating requirements.
6. Inspect cabinet cooling: Ensure that the cooling airflow and cabinet clearances meet the requirements for the selected configuration.
7. Check the DC-bus connections: Verify conductor sizing, terminal condition, polarity and the connection arrangement against the system documentation.
8. Inspect motor output wiring: Check the motor cable, protective earth and output connections for damage or loose terminations.
9. Verify feedback and control wiring: Confirm that the motor feedback device, control interface and associated wiring match the configured drive application.
10. Review protection and braking: Check the specified semiconductor protection, upstream circuit protection and the method used to handle regenerative energy.
11. Commission the motor: Verify rotation direction, control response, current behavior and operation under a controlled load before returning the equipment to production.
12. Record maintenance findings: Document the module reference, mounting arrangement, motor data, parameter configuration and any recorded faults or abnormal operating conditions.

Compatible System Components

Recommended Related Models

Key Advantages

• Converts DC-bus power into controlled AC output for compatible motors.
• Supports high-power industrial motor-control applications.
• Fits modular Unidrive SPM drive architectures.
• Allows docked or undocked installation when the system requirements are met.
• Can operate within shared DC-bus systems using compatible rectifier and inverter components.

Technical FAQs

What is the difference between the SPMD1422 and the SPMC2402?

The SPMD1422 is an inverter module that converts DC-bus power into controlled AC output for a motor. The SPMC2402 is a controlled rectifier that converts incoming AC power into DC power for the drive system. They perform different functions and are not interchangeable.

What motor power is associated with the SPMD1422?

The SPMD1422 is associated with a typical heavy-duty motor rating of 110 kW at 400 V and 150 hp at 460 V. The final selection must account for the actual motor current, duty requirements, supply conditions and installation arrangement.

Does the mounting arrangement affect the inverter’s operating rating?

Yes. Docked and undocked installations can have different cooling conditions and drive ratings. The applicable rating must be checked against the actual arrangement and operating requirements.

Can multiple SPMD1422 modules share a common DC bus?

A common DC-bus arrangement is possible within a properly engineered Unidrive SPM system. The rectifier capacity, bus connections, protection, inverter configuration and any required output-sharing components must all be selected for the combined installation.