preheating current

例句：

1. 1.The machine requires preheating before starting operation.
   这台机器在开始运行前需要预热。
2. 2.During the preheating process, the temperature should be gradually increased.
   预热过程中，温度应该逐渐升高。
3. 3. The preheating current is crucial for ensuring the safe operation of the equipment.
   预热电流对于确保设备安全运行至关重要。