The voltage in the telephone line is 20V. When a call comes in, the phone line voltage rises to 48V and the phone rings. When the off-hook responds, the telephone line voltage drops to 10V again. The telephone line has a certain limit on the current, and a fuse is installed before entering the cable. The switching equipment supplies electricity when the modules are out. The telephone line is powered by 48V. The resistors are connected in series on the line. Each end is about 600 ohms. If the load is slightly exceeded, the switch will think that it will go off-hook, which will affect the communication. When the phone rings, the power consumption is the largest. The line design has taken into account the current of normal calls. The average DC power of 48V per household does not exceed 20 mA. When a user receives 100A for a long time, it will be monitored by the monitoring device and automatically shut down the user. At present, the program-controlled switch uses a DC feed voltage of 48V. Since the lead battery is floating, the actual voltage is about 50V when the phone hangs up. When the phone is off-hook, the DC link of the phone is connected, and there is current in the phone. At this time, the voltage drops to 7-10V, depending on the length of the line and the phone. The current after the phone is off-hook is different, and is affected by subscriber lines, telephones, and intra-office switching equipment. Generally at 20-30mA. The current should be around 5 microamps when hanging up. When the bell rings, the ringing voltage is 75V and the AC voltage is 16-25Hz. The original crossbar switch hangs 60V Mandarin phone When the local telephone station hangs up, DC 48V. Ringing: 20HZ, above 75V Call: depending on the line and phone quality, generally between 6-12V DC Small switch: DC voltage is generally two: 24 or 48. Ringing is similar to talking. Although the voltage is above 36V, it is not harmful to people because of its extremely small current. Rest assured. Strong Suction Vacuum Cleaner,Strong Suction Robot Vacuum Cleaner,Strong Suction Wired Vacuum Cleaner,High Power Vacuum Cleaner NingBo CaiNiao Intelligent Technology Co., LTD , https://www.intelligentnewbot.com
Program-controlled switch hangs up 48V
Bell current voltage 90V
Hang up 48V, ringing 90V, call 8V
However, the value is not accurate and will vary within a certain range. Given only the general value