Product Overview

The Schneider Electric ATS48C21Y Altistart 48 Soft Starter is an industrial motor-starting and stopping device designed for three-phase asynchronous motors. It belongs to the Altistart 48 series and is intended for applications that require controlled motor acceleration, reduced starting current, and smooth deceleration.

During direct-on-line starting, an AC motor can draw a high inrush current and produce substantial mechanical stress. These effects can place additional demands on electrical distribution systems, motors, couplings, belts, pumps, and other connected equipment. A soft starter helps manage these conditions by controlling the voltage applied to the motor during startup.

The ATS48C21Y uses torque-control technology and current limiting to provide controlled motor starting. It is suitable for demanding industrial applications, including pumping systems, ventilation equipment, compressors, and other machinery driven by asynchronous motors.

The device supports a rated supply voltage range of 208–690 V AC and operates with 50/60 Hz power supplies. Its device rating is 180 A, while the applicable motor power depends on supply voltage and operating duty. For example, the published ratings include 90 kW at 400 V for severe applications and 110 kW at 400 V for standard applications.

The ATS48C21Y also provides motor and starter thermal protection functions, phase-failure protection, configurable inputs and outputs, and Modbus serial communication over an RS485 interface. These capabilities allow it to participate in industrial motor-control systems alongside PLCs, HMIs, sensors, and electrical protection equipment.

This model is part of a discontinued product range. It remains relevant to maintenance and replacement projects involving existing Altistart 48 installations. Before purchasing, engineers should verify the complete model number, electrical ratings, control supply, and communication requirements.

Technical Specifications

Note: Motor power ratings vary with supply voltage and duty classification. The device rating, operational current, and motor power should not be treated as interchangeable values. Confirm the motor’s nameplate current and the manufacturer’s selection tables before installation.

Function and Working Principle

The ATS48C21Y controls the electrical conditions during motor starting and stopping. Rather than applying full supply voltage to the motor immediately, it regulates the motor’s electrical input to achieve a controlled acceleration process.

1. Controlled Motor Starting

When a start command is received, the soft starter gradually increases the voltage applied to the motor according to its configured starting parameters.

This helps reduce the sudden electrical and mechanical effects associated with direct-on-line starting. The motor accelerates more progressively, allowing connected machinery to reach operating speed with less abrupt movement.

This function is particularly useful for pumps, conveyors, compressors, and other equipment where sudden acceleration can affect the production process or mechanical components.

2. Torque Control

The Altistart 48 series uses torque-control technology to manage motor acceleration.

Torque control is useful when the load requires a controlled increase in mechanical force during startup. For example, a pump may need gradual acceleration to reduce pressure disturbances in the connected pipeline.

The ATS48C21Y allows the starting behavior to be adjusted according to the characteristics of the motor and driven equipment. Correct commissioning is essential because the required torque and acceleration profile vary between applications.

3. Starting Current Limitation

Large AC motors can draw several times their rated current during direct starting. This can cause voltage dips, electrical disturbances, and additional stress on power distribution equipment.

The ATS48C21Y supports adjustable current limiting. By controlling the motor’s starting conditions, it can help reduce excessive inrush current when compared with an uncontrolled direct-on-line start.

The current limit must be selected carefully. Setting it too low may prevent the motor from developing enough torque to accelerate the load.

4. Controlled Motor Stopping

The soft starter can also control motor deceleration. Instead of allowing the motor to stop without controlled electrical intervention, the device can apply a configured stopping profile.

This can be beneficial for applications where abrupt stopping may cause mechanical shock or hydraulic disturbances.

For pumping systems, controlled stopping can help reduce pressure transients under suitable operating conditions. The actual result depends on the pump characteristics, pipeline design, fluid conditions, and selected stopping parameters.

5. Motor and Starter Protection

The ATS48C21Y includes protection functions intended to monitor operating conditions and help detect abnormal situations.

These functions include motor thermal protection, starter thermal protection, and phase-failure protection. They help reduce the risk of damage caused by unsuitable electrical or operating conditions.

Protection settings must be configured according to the motor’s rated current and the application requirements. The soft starter does not replace the need for correctly selected upstream short-circuit protection and appropriate electrical safety measures.

Role in Industrial Control Systems

The ATS48C21Y can serve as a motor-starting and stopping component within a larger industrial automation system. It works alongside electrical protection equipment, PLCs, operator interfaces, and field devices.

PLC Integration

A programmable logic controller can manage the operating sequence of a motor-driven machine and issue start or stop commands to the soft starter.

For example, a PLC-controlled pumping station may use pressure transmitters and level sensors to determine when a pump should start or stop. The ATS48C21Y then controls the motor’s starting or stopping process according to its configured parameters.

Its Modbus RS485 interface can also support communication with compatible automation equipment. Engineers should verify the communication settings, wiring, addressing, and PLC protocol configuration before commissioning.

HMI Monitoring

An HMI can provide operators with information about motor operation, alarms, and equipment status.

Through a compatible PLC or Modbus connection, the control system can make selected soft-starter information available to the operator. This can simplify troubleshooting and help maintenance personnel identify abnormal operating conditions.

Electrical Distribution Integration

The soft starter is installed in the motor power circuit and must be coordinated with upstream protective devices, isolation equipment, and the motor.

Proper electrical coordination helps ensure that the starter operates within its rated limits and that faults can be handled safely.

Process Equipment Coordination

In an automated production line, the ATS48C21Y can help coordinate the startup and stopping of motors used in pumps, fans, compressors, and material-handling machinery.

The PLC or process-control system determines when the equipment should operate, while the soft starter manages the motor’s starting and stopping behavior.

Industrial Applications

The Schneider Electric ATS48C21Y is designed for demanding industrial motor-control applications. Its 180 A device rating and application-dependent motor power ratings make it suitable for appropriately sized motors in industrial installations.

1. Industrial Pumping Systems

Pumping systems are among the main applications of the Altistart 48 series.

Starting a large pump motor directly can create high starting current and sudden pressure changes. The ATS48C21Y can provide controlled acceleration to help reduce mechanical stress and improve the starting behavior of the pumping system.

Typical applications include:

• Industrial water supply systems.
• Water treatment plants.
• Process-fluid circulation systems.
• Cooling-water pumps.
• Industrial drainage and wastewater equipment.

The selected starting and stopping profiles should be matched to the pump and pipeline characteristics.

2. Ventilation and Fan Systems

Large ventilation systems often use three-phase asynchronous motors to drive industrial fans.

A soft starter can reduce the abrupt mechanical effects of motor startup and help control acceleration. This is useful in facilities where multiple fans operate as part of a coordinated ventilation system.

Applications may include industrial buildings, manufacturing plants, process ventilation, and infrastructure facilities.

3. Industrial Compressors

Compressors can impose significant starting loads on their motors. The starting requirements depend on compressor type, pressure conditions, mechanical design, and unloading arrangements.

The ATS48C21Y can be considered for compatible compressor motor applications where its current and duty ratings meet the equipment requirements.

The compressor manufacturer’s starting procedure must be followed when configuring the soft starter.

4. Conveyor and Material-Handling Equipment

Conveyor systems often require controlled motor acceleration to reduce sudden movement and mechanical stress.

The ATS48C21Y can support controlled startup for compatible conveyor motors used in manufacturing, warehousing, and bulk-material handling.

For high-inertia or heavily loaded conveyors, engineers should evaluate the required starting torque, acceleration time, and mechanical braking arrangements.

5. Industrial Processing Machinery

Many production facilities use large asynchronous motors to drive mixers, processing equipment, auxiliary machinery, and other rotating equipment.

A soft starter can help manage the electrical and mechanical conditions during startup and stopping. The ATS48C21Y may be suitable when the motor’s rated current, power, and duty requirements match the starter’s specifications.

Installation and System Integration

Correct installation is essential for safe operation and reliable motor starting. The ATS48C21Y should be installed by qualified personnel familiar with industrial motor-control systems.

1. Verify Supply Voltage and Motor Ratings

Before installation, confirm that the supply voltage is within the device’s specified 208–690 V AC range.

Check the motor nameplate for:

• Rated voltage.
• Rated current.
• Rated power.
• Frequency.
• Rated speed.
• Connection configuration.
• Starting and load requirements.

The device’s 180 A rating should not be used as a substitute for checking the applicable motor power and duty selection tables.

2. Confirm Control Circuit Supply

The ATS48C21Y uses a separate control circuit supply rated at 110–230 V AC.

The control supply must be connected according to the manufacturer’s wiring instructions. Verify the voltage and frequency before energizing the control circuit.

3. Mounting and Cabinet Design

The supplied product dimensions are 380 × 320 × 265 mm, with a weight of 18.2 kg.

The manufacturer’s dimensional information identifies the unit as approximately 380 mm high, 320 mm wide, and 265 mm deep.

The cabinet should provide sufficient space for mounting, power wiring, control wiring, maintenance access, and ventilation.

The ATS48C21Y uses forced-convection cooling. Ensure that the required airflow is available and that the cooling path is not obstructed.

Its IP00 protection rating means that the device does not provide a complete protective enclosure. It must be installed in a suitable electrical cabinet that provides protection against accidental contact and environmental contamination.

4. Configure Starting and Stopping Parameters

After completing the electrical connections, configure the motor parameters and starting behavior.

Important settings include:

• Motor rated current.
• Starting torque.
• Current limit.
• Acceleration time.
• Deceleration or stopping time.
• Motor thermal protection.
• Control command source.

These values should be selected according to the motor manufacturer’s recommendations and the mechanical characteristics of the driven equipment.

5. Connect Communication Interfaces

The ATS48C21Y supports Modbus communication over an RS485 serial interface.

When connecting it to a PLC or supervisory system, verify the communication address, baud rate, parity, wiring polarity, and network termination requirements.

The communication system should be tested before the equipment is placed into normal operation.

6. Commissioning and Functional Testing

Before returning the motor to service, inspect the power and control wiring, verify protective-device coordination, and check the grounding arrangement.

Perform controlled tests to confirm:

• Correct motor rotation.
• Proper start-command response.
• Appropriate acceleration behavior.
• Current-limiting operation.
• Correct stopping behavior.
• Protection and alarm responses.
• Communication with the PLC or HMI, where applicable.

Record the final configuration and commissioning results for future maintenance.

Compatible System Components

The ATS48C21Y is designed to operate as part of a complete motor-control installation.

The listed components are examples of equipment used in a complete installation. They are not necessarily supplied with the ATS48C21Y.

Alternative Models and Replacement Considerations

The Altistart 48 series has been discontinued, so replacement planning should consider both legacy equipment compatibility and current product availability.

When replacing the ATS48C21Y, compare:

• Supply voltage and frequency.
• Rated operational current.
• Motor power under normal and severe duty.
• Control circuit voltage.
• Starting torque and current-limiting requirements.
• Number and type of control inputs and outputs.
• Modbus communication requirements.
• Mounting dimensions and ventilation.
• Protection functions.
• PLC and HMI integration requirements.

A newer soft starter should not be assumed to be a direct plug-in replacement. Terminal assignments, communication registers, parameter structures, and mounting dimensions may differ.

Key Advantages

Controlled Motor Starting

The ATS48C21Y regulates motor acceleration to reduce the abrupt electrical and mechanical effects associated with direct-on-line starting.

Adjustable Current Limiting

Its current-limiting function allows engineers to configure starting behavior according to the motor and load requirements.

Torque-Control Technology

Torque control supports controlled motor acceleration and is useful in applications requiring a managed increase in mechanical force.

Controlled Stopping

The soft starter can provide a configured stopping profile for applications where abrupt motor stopping is undesirable.

Integrated Protection Functions

Motor thermal protection, starter thermal protection, and phase-failure protection help monitor important operating conditions.

Modbus Communication

The RS485 Modbus interface allows the soft starter to exchange information with compatible PLCs and industrial monitoring systems.

Industrial Application Range

The Altistart 48 series is designed for demanding motor-control applications, including pumps, fans, compressors, and other industrial machinery.

Technical FAQs

1. What is the Schneider Electric ATS48C21Y?

The ATS48C21Y is an Altistart 48 soft starter designed for three-phase asynchronous motors. It provides controlled starting and stopping using torque-control technology and current limiting.

2. What is the rated current of the ATS48C21Y?

Its device rating is 180 A. The applicable operating current and motor power depend on the selected application and duty classification. Always consult the manufacturer’s selection data.

3. What supply voltage does the ATS48C21Y support?

It supports a rated supply voltage range of 208–690 V AC and a supply frequency of 50/60 Hz.

4. What is the motor power rating at 400 V?

The published motor power ratings at 400 V are 110 kW for standard applications and 90 kW for severe applications.

5. Does the ATS48C21Y support Modbus communication?

Yes. It supports Modbus serial communication through an RS485 interface. The communication settings must be configured to match the connected PLC or supervisory system.

6. What is the control circuit voltage?

The control circuit supply is rated at 110–230 V AC. Verify the actual supply voltage and wiring requirements before commissioning.

7. What types of motors can it control?

It is designed for three-phase asynchronous motors. The motor’s voltage, rated current, power, and starting requirements must fall within the applicable selection limits.

8. What is the protection rating?

The device has an IP00 protection rating. It should therefore be installed inside a suitable electrical enclosure that provides the required protection against contact and environmental conditions.

9. Is the ATS48C21Y still manufactured?

The ATS48C21Y was discontinued on May 2, 2023. It is listed as discontinued with service support status. Buyers should verify availability and support arrangements before purchasing.

10. What should be checked before purchasing a replacement?

Confirm the complete model number, rated voltage, current, motor duty, control circuit voltage, communication interface, physical condition, and included accessories. For used equipment, request photographs of the nameplate and terminals and ask for appropriate functional testing.

Procurement and Maintenance Recommendations

The Schneider Electric ATS48C21Y is a discontinued industrial soft starter, so accurate model identification is especially important when purchasing replacement equipment.

Before placing an order, verify that the catalog number is ATS48C21Y and check the device rating, supply voltage range, motor power requirements, and control circuit voltage. Confirm that the unit includes the required communication and control interfaces for the existing installation.

For used or refurbished products, inspect the enclosure, power terminals, control terminals, cooling fans, and visible electronic components. Request clear photographs of the nameplate and product condition. Where the soft starter is intended for critical machinery, request functional testing and confirm the supplier’s warranty and return policy.

During routine maintenance, keep the cabinet clean and maintain the required cooling airflow. Inspect electrical connections, cable insulation, grounding, and ventilation components according to the manufacturer’s maintenance recommendations.

For replacement projects, compare the existing parameter settings and control wiring with the proposed replacement. If upgrading to a newer soft-starter family, review the communication interface, terminal assignments, protection functions, and commissioning requirements before making the change.

Conclusion

The Schneider Electric ATS48C21Y Altistart 48 Soft Starter is an industrial motor-control device designed for three-phase asynchronous motors. It supports 208–690 V AC supplies, has a 180 A device rating, and provides application-dependent motor power ratings of up to 110 kW at 400 V for standard-duty operation.

Its torque-control starting method, adjustable current limiting, controlled stopping, motor protection functions, and Modbus RS485 communication make it suitable for a range of industrial motor-control applications.

Although the model has been discontinued, it remains relevant to maintenance and replacement projects involving existing Altistart 48 installations. Accurate electrical selection, configuration verification, and careful commissioning are essential for reliable operation.