What type of manual starter is typically used for three-phase motors?

The most suitable type of manual starter for three-phase motors is the integral horsepower starter. This starter is designed to handle the higher power requirements typical of three-phase motors, which are often used in industrial applications where greater torque and power are needed. Integral horsepower starters create a direct connection to the motor, providing the necessary voltage and current without any intermediate control or variation in power supply.

This type of manual starter incorporates overload protection to safeguard the motor from excessive current, which can lead to damage. This protection is particularly important for three-phase motors because they can draw significant startup currents, and robust control is essential to ensure operational safety and longevity.

In contrast, other types of starters, such as the direct-on-line starter, are simpler and can be used for smaller motors but may not be optimized for the larger loads commonly associated with three-phase systems. Soft starters are designed to gradually increase motor speed and reduce inrush current but are not typically employed as a manual starter for three-phase motors. Multi-speed starters can change the speed of the motor but again may not provide the direct handling and robustness required for all three-phase applications.

Thus, the integral horsepower starter stands out as the best option for managing the demands and operational characteristics of three-phase motors effectively.