Motors with High Overload Capacity

Frequently Asked Questions

• What is better for a conveyor: a soft starter or a VFD?

• The choice depends on needs and budget: **Soft Starter:** Primarily provides **soft start and soft stop**, reducing mechanical stress and electrical inrush current. It does **not** control speed during running (motor runs at full speed). It is a **cost-effective solution** for applications that only need to manage start/stop dynamics. **Variable Frequency Drive (VFD):** Provides **full speed control**, from zero to above base speed. Enables soft start/stop, **precise speed regulation** (critical for synchronization), and can provide **energy savings** if the conveyor runs at reduced speed. It is more expensive but offers far greater functionality. For simple conveyors with fixed speed, a soft starter may suffice. For complex systems, sorting lines, or where speed adjustment is needed, a VFD is required.

• How do I synchronize the speed of two or more conveyor motors?

• Synchronization is best achieved using **VFDs in a master-follower configuration**. One VFD/motor is designated as the "master," controlling its speed based on a setpoint. The other VFDs/motors are "followers." The follower VFDs receive a speed reference signal (via analog 4-20mA or digital network) from the master and adjust their output to match. For higher precision, especially if maintaining exact positional relationship is critical (like on a single long belt with multiple drives), **encoder feedback** is used on each motor, and the VFDs operate in closed-loop vector control mode. This allows them to maintain speed within a fraction of an RPM, regardless of load variations on different sections.

• Why does my conveyor motor keep tripping on overload during start-up?

• This is a common issue, usually indicating that the motor's starting torque is insufficient for the **breakaway friction** of the loaded conveyor. Causes and solutions: 1) **Excessive Load:** The conveyor may be overloaded or material may be packed/blocked. Clear the blockage. 2) **Incorrect Motor Sizing:** The motor may be undersized for the actual starting torque requirement. Consider a motor with higher starting torque (NEMA Design C or equivalent) or a wound rotor motor. 3) **Poor Starting Method:** A direct-on-line start may cause excessive current trip before the motor develops full torque. Implement a **soft starter or VFD** to provide a controlled, high-torque start with limited current. 4) **Mechanical Binding:** Check for seized bearings, misaligned gearboxes, or a damaged belt creating excessive drag. Address the mechanical issue first.