Technical Specifications

FAQ

1. What is the main function of the Schneider ATS48C79Q soft starter?

The Schneider Electric ATS48C79Q is a high-current Altistart 48 soft starter designed to control the starting and stopping of three-phase asynchronous motors. Rather than applying the full supply voltage to the motor immediately, the ATS48C79Q controls the electrical conditions and torque during acceleration so that the motor can reach operating speed more smoothly.

The unit is designed for large industrial motors and demanding applications such as pumps, fans, compressors, conveyors and other heavy-duty machinery. Controlled starting can reduce the electrical impact associated with direct-on-line starting while also reducing mechanical shock throughout the driven system.

The ATS48C79Q also incorporates motor thermal protection, starter thermal protection and line phase-failure detection. This allows the device to provide both motor starting control and important protection functions within an industrial motor control system.

2. What motor power range can the ATS48C79Q support?

The applicable motor power depends on the supply voltage, motor connection method and application duty. The ATS48C79Q can be used with both in-line and inside-delta motor connections, and the permissible motor rating changes according to these configurations.

At 230 V, the applicable power can be approximately 220 kW for a standard-duty in-line application, while specified inside-delta configurations can support higher motor power depending on the duty classification. At 400 V, the unit can be used with approximately 355 kW in severe-duty in-line applications and approximately 400 kW in standard-duty in-line applications. Inside-delta configurations can reach approximately 500 kW in severe-duty applications and up to approximately 630 kW in standard-duty applications.

The maximum power figure should not be treated as a universal rating. Motor rated current, starting torque, acceleration time, operating cycle and connection method should all be considered when selecting the soft starter.

3. What power supply does the ATS48C79Q require?

The ATS48C79Q is designed for three-phase AC systems with a rated supply voltage of 230–415 V and an applicable supply range of approximately 195–456 V. The normal operating frequency is 50–60 Hz, with an applicable frequency range of approximately 47.5–63 Hz.

Before installation, the incoming three-phase supply should be checked against the soft starter requirements and the motor nameplate. Voltage balance, phase continuity and phase sequence should also be verified.

The ATS48C79Q supports both in-line and inside-delta motor connections. Because these configurations have different current relationships and application ratings, the power wiring and configuration must correspond to the selected connection method.

Incorrect supply voltage, wiring or configuration can lead to starting problems, excessive current, phase-related protection trips or abnormal motor operation.

4. How does the ATS48C79Q reduce motor starting current and mechanical stress?

The ATS48C79Q controls the motor acceleration process rather than applying full line voltage instantaneously. Its torque-controlled starting method can limit starting current to approximately 5 × In while maintaining controlled motor acceleration.

For large motors, direct-on-line starting can produce a substantial current surge and cause voltage disturbances within the electrical system. It can also generate a sudden torque increase that places significant stress on shafts, couplings, gearboxes, belts and other mechanical components.

By providing controlled acceleration, the ATS48C79Q allows the motor to build up speed progressively. This is particularly beneficial for large pumps, conveyors, compressors and fans where abrupt acceleration can cause mechanical or process-related problems.

In pumping systems, controlled starting and stopping can also reduce sudden changes in flow and pressure. The acceleration parameters should nevertheless be selected according to the actual motor and load characteristics. Excessively short acceleration can reduce the benefits of soft starting, while excessively long acceleration can increase thermal stress.

5. What protection functions are integrated into the ATS48C79Q?

The ATS48C79Q provides several protection functions intended to protect the motor and soft starter during operation. These include motor thermal protection, starter thermal protection and line phase-failure detection.

Motor thermal protection monitors the thermal load associated with motor operation. This is particularly important when the motor is heavily loaded, takes a long time to accelerate or is started repeatedly.

Starter thermal protection protects the internal power components from excessive thermal stress. Because the ATS48C79Q is designed for high-current motor applications, repeated or prolonged starting can generate significant heat within the power section.

Line phase-failure detection helps identify abnormal three-phase supply conditions. Operating a three-phase motor with a missing phase can result in current imbalance, reduced torque and excessive motor heating.

The protection parameters should be configured according to the motor nameplate and actual application. Incorrect settings may result in nuisance trips or inadequate protection.

6. Can the ATS48C79Q communicate with a PLC or automation system?

Yes. The ATS48C79Q provides an RS485 multidrop communication interface and supports Modbus communication. This allows the soft starter to exchange operating and diagnostic information with PLCs, industrial controllers and supervisory systems.

Within an automation system, a PLC can monitor available soft starter status information, fault conditions and operating data through the communication network. This makes it possible to integrate the motor starter into a centralized equipment monitoring and control system.

When commissioning Modbus communication, the device address, baud rate and other communication parameters must be configured consistently with the PLC or network master. The RS485 wiring and RJ45 connection should also be checked carefully.

If communication fails while the soft starter itself appears to operate normally, troubleshooting should begin with the communication address, baud rate, cable, connector and PLC communication program. A communication failure does not necessarily indicate a fault in the power section of the ATS48C79Q.

7. Why might the ATS48C79Q trip while the motor is accelerating?

A trip during acceleration can result from several different conditions. The first step is to identify the specific fault or diagnostic information reported by the soft starter rather than immediately replacing the unit or changing protection settings.

The motor rated current and configured parameters should be checked first. The starting time and torque settings should then be compared with the actual load requirements. If the mechanical load requires excessive starting torque, the motor may accelerate too slowly, increasing current and thermal stress during the starting cycle.

The electrical supply should also be inspected for phase loss, abnormal voltage or severe voltage imbalance. Motor terminals and the selected in-line or inside-delta connection must be checked to ensure that the power wiring matches the application configuration.

For systems with frequent starts, the starting frequency and time between successive starts should also be evaluated. Heat can accumulate during repeated starting, eventually causing thermal protection to operate even when individual starts appear normal.

8. What should be considered when selecting the ATS48C79Q for heavy-duty applications?

Selection of the ATS48C79Q for a heavy-duty motor should be based on more than the motor’s nominal kW rating. Motor rated current, supply voltage, starting torque, acceleration time, number of starts per hour and load characteristics should all be evaluated.

The ATS48C79Q has different permissible motor ratings depending on whether the motor is connected in-line or inside-delta and whether the application is standard or severe duty. For example, a 400 V inside-delta configuration can provide a significantly higher applicable motor power rating than an equivalent severe-duty in-line configuration.

Thermal conditions are particularly important in heavy-duty applications. Long acceleration times and frequent starts increase the thermal load on both the motor and the soft starter. Ambient temperature and cabinet ventilation should therefore also be considered during system design.

Before commissioning, the motor rated parameters, starting torque, acceleration time, protection settings, control inputs and communication parameters should be configured correctly. Proper sizing and commissioning allow the ATS48C79Q to provide reliable starting performance and appropriate protection for large industrial motors.