Technical Specifications

FAQ

1. What is the main function of the Schneider ATS48D88Q soft starter?

The Schneider ATS48D88Q is an Altistart 48 soft starter designed to control the starting and stopping of three-phase asynchronous motors. Instead of applying the full supply voltage directly to the motor, the soft starter controls the motor voltage and current during acceleration, helping reduce starting current and mechanical stress. It uses torque-controlled starting and can limit starting current to approximately 5 times the motor rated current. This makes it suitable for applications where conventional direct-on-line starting would create excessive current or mechanical shock, including pumps, fans, compressors, conveyors, and other industrial machinery.

2. What motor power range is supported by the ATS48D88Q?

The applicable motor power depends on the supply voltage, connection method, and whether the application is classified as standard or severe duty. At 400 V with a motor-delta connection, the ATS48D88Q can be used with motors up to 75 kW for standard applications and 55 kW for severe applications. For connection in the motor supply line at 400 V, the corresponding ratings are 45 kW and 37 kW. At 230 V, the supported ratings also vary according to the connection method and duty classification. Therefore, motor selection should not be based solely on the nominal 81 A rating; the actual starting conditions, motor current, duty cycle, connection method, and application load must all be considered.

3. What supply voltage does the ATS48D88Q require?

The ATS48D88Q is designed for a three-phase supply voltage of 230 to 415 V AC, with an allowable tolerance of approximately -15% to +10%. Its specified supply frequency is 50 to 60 Hz, with a frequency tolerance of -5% to +5%. The unit can therefore be used in a range of industrial low-voltage motor applications within these limits. Before commissioning, the incoming supply should be checked to ensure that voltage, frequency, phase sequence, and protection arrangements are suitable for the soft starter and connected motor. The control supply requirements should also be checked separately from the main motor supply.

4. How does the ATS48D88Q reduce motor starting current?

The ATS48D88Q uses controlled semiconductor switching to regulate the voltage applied to the motor during acceleration. Instead of immediately applying full line voltage, the soft starter gradually increases the motor’s effective supply, allowing the motor current and torque to build up in a controlled manner. The starting current can be limited to a configured value, with the ATS48D88Q supporting a starting-current limit of up to approximately 5 times the motor rated current. This reduces the electrical impact on the supply network and can also reduce mechanical shock transmitted to couplings, gearboxes, belts, pumps, and other driven equipment.

5. What communication protocol is supported by the ATS48D88Q?

The ATS48D88Q supports Modbus communication through an RS-485 multidrop interface. The communication interface uses an RJ45 connector, and selectable transmission rates include 4800, 9600, and 19200 bps. Up to 31 nodes can be supported in the applicable communication architecture. Modbus communication can be used for exchanging operating information, status data, commands, and diagnostic information with a PLC, HMI, supervisory system, or other compatible control equipment. When commissioning the communication network, the device address, transmission rate, communication parameters, RS-485 wiring, and network termination should be checked carefully.

6. What protection functions are available on the ATS48D88Q?

The ATS48D88Q incorporates several protection functions intended to protect both the motor and the soft starter. These include line phase-failure detection, motor thermal protection, and starter thermal protection. Motor thermal protection helps prevent excessive thermal loading caused by prolonged or abnormal operating conditions. Starter thermal protection monitors the thermal condition of the power electronics and helps prevent damage caused by excessive heating. Protection functions should be configured according to the actual motor and application requirements. Proper upstream short-circuit protection and correctly selected motor protection remain important because the soft starter should be considered part of a complete motor-control protection system rather than the only protective device.

7. How should the ATS48D88Q be configured for a pump or fan application?

For pumps and fans, configuration should begin with the motor nameplate information and the actual load characteristics. The motor rated current, supply voltage, motor connection, acceleration requirements, and required starting torque should be entered or selected appropriately. The acceleration and deceleration parameters should then be adjusted so that the motor reaches operating speed smoothly without unnecessarily extending the starting period. Pump applications may benefit from controlled stopping to reduce hydraulic shock, while fan applications may require different acceleration characteristics because of their inertia. After configuration, the motor should be tested under normal operating conditions while monitoring current, acceleration time, thermal behavior, and any active protection functions.

8. What should be checked when troubleshooting an ATS48D88Q that does not start the motor?

Troubleshooting should begin by checking the incoming three-phase supply, control supply, motor wiring, protection devices, and active fault indications. Verify that the motor is correctly connected and that the soft starter recognizes the required Run and Stop commands. The motor’s rated current and other configuration parameters should also be checked because incorrect settings can prevent proper starting or cause protection functions to operate. If a phase-failure or thermal fault is displayed, inspect the corresponding power connections, motor condition, cooling system, and operating load. For communication-controlled applications, the Modbus address, baud rate, RS-485 wiring, and control commands should also be verified. If the unit repeatedly trips during acceleration, investigate excessive starting torque requirements, prolonged acceleration, motor loading, current-limit settings, and the thermal condition of the soft starter before replacing any components.