Worn motor brushes, a bad drive motor, a faulty motor overload switch, using an improper extension cord and binding up the saw blade can cause the table saw's motor overload to trip.
A long or lightweight extension cord can cause a voltage drop that overheats the motor and causes the overload to trip. Use a shorter cord or a heavy-duty extension cord that can handle the current draw of the table saw. For a 120-volt table saw plugged into an outlet protected by a 15-amp circuit breaker, extension cord length typically shouldn't exceed 25 feet.
The motor can overheat if the saw blade binds up when cutting a work piece. Replace a dull or damaged cutting blade so it doesn't bind up when cutting a work piece. Using the wrong type of blade for cutting the work piece can also bind up the blade when cutting. Use the right type of blade for the work piece that you're cutting.
Worn motor brushes or a bad drive motor can cause the overload to trip. Check the condition of the carbon motor brushes and replace if they're worn. Replace the motor if it overheats or won't spin the blade when cutting light work pieces.
A faulty motor overload switch will trip even when the motor doesn't overheat. Replace the motor overload if it constantly shuts off the motor when the motor isn't overheating.