电动机的过载保护指的是在电机承受超过其额定负载时，通过一系列保护措施保护电动机的安全运行。电动机有多种过载保护方法，其中最常见的方法包括热继电器保护、电流保护和温度保护。

一、热继電器保護：

熱繼電器是最基本也是最常用的電動機過載保護裝置之一。其工作原理是通過電流經過線圈產生的熱量來檢測電機的負載情況。当電機工作時，電流通過熱繼電器的線圈，使線圈加熱並膨脹，当線圈溫度達到設定值時，熱繼電器中的觸點會自動跳開，切斷供應，以此停止電機工作。当再次回到正常負載範圍內時，熱繼 電器將會恢復到初始狀態，並讓電機持續運行。

二、Electric Current Protection：

Electric current protection is a method of detecting overloading by measuring the electric current flowing through the motor. A current sensor is used to monitor the motor's running current, and when the load exceeds the rated value, the current will exceed a predetermined threshold. When this happens, an electrical device will automatically disconnect power to prevent damage to the motor.

三、Temperature Protection：

Temperature protection measures are based on monitoring temperature changes in motors during operation. If overheating occurs due to overloading, temperatures will rise. Temperature protection devices usually include thermocouples or thermal resistors that measure motor temperatures. When temperatures exceed set values, temperature protectors automatically cut off power supply to reduce temperatures and avoid damage from overload.

Combining heat relay protection with electric current protection and temperature control can provide double-layered security for protecting motors against overload events and ensuring safe operation of motors under various operating conditions.

Apart from these mentioned protective methods, there are other types of protective devices available for use with motors such as circuit breakers and soft starters which may be appropriate depending on specific situations or applications; it is crucial to choose suitable protective devices for each type of machine in order ensure their reliable performance within safety limits.

In conclusion, protecting electric machines against overload conditions is essential for maintaining their proper functioning without risk of mechanical failure or fire hazards caused by overheating or excessive currents drawn from sources like mains voltage supplies provided either directly via conductive wires connected between two different points inside building space where many appliances exist together but have varying needs accordingly (e.g., lighting systems requiring lower amperage) while also considering factors related directly impacting efficiency i.e., energy consumption rates per hour worked at given levels below 90% compared higher usage levels exceeding 110%.