时间继电器认识 类型认识：
Knowledge types of time relay:
电磁式、空气阻尼式、电动式、电子式 直流电磁式时间继电器——用于直流电气控制电路中，只能直流断电延时动作。 优点：结构简单、运行可靠、寿命长;缺点：延时时间短。 空气阻尼式时间继电器——利用空气阻尼作用获得延时。 分：通电延时、断电延时两种。 电子式时间继电器——分R-C式晶体管和数字式时间继电器。 优点：延时范围宽、精度高、体积小、工作可靠。
Electromagnetic, air damping type, electric type, electronic type DC electromagnetic type time relay for DC electrical control circuit, only DC power delay action. Advantages: simple structure, reliable operation, long service life; shortcomings: short delay time. Air damping time relay - the time delay is achieved by air damping. Points: power delay, power delay two kinds. Electronic time relay -- divided R-C transistor and digital time relay. Advantages: wide delay range, high precision, small size and reliable operation.