Definition of: ISDN (Integrated Services digital Network) an international standard for switched, digitaldial-up telephone service for voice and data.
定义：ISDN(综合服务数字网络)，是一个国际转换标准，是为了语音和数据的数码拨号上网电话服务。
2
Introduction was made to the composition and working principle of a power-off time delay relay which adopts CMOS digital circuit, digitaldial disc for switch setting and without auxiliary power.
介绍了一种采用CMOS数字电路、数字拨盘开关整定、无辅助电源的断电延时继电器的组成及工作原理。
3
The article discusses about the proper selection of static relay test points through introducing the contactor sketch of rectifying static relays with digitaldial switches and easy-happening faults.