Monday, December 27, 2010
【 Weak current College 】 phone line of voltage and current parameters 】
Phone line voltage is 20V. When a phone call, the telephone line voltage rise to 48V, the phone will ring. When you pick up an answer, the telephone line will drop to 10V.
Telephone line on the current have limited access to cable before installing a fuse. Switching device for a whole module out there is electricity, the telephone line is the power supply, 48V has threaded on the line, the resistance is approximately 600 ohms at each end, load slightly exceeded, the switch will be considered off-hook, which would affect communications. When the phone rings is the maximum power consumption, circuit design time took into account the normal call of current, average household 48V DC 20 Ma. In a user-end long time taken when electric 100A is monitoring equipment monitoring, auto-close to the user.
The current use of PABX, 48V DC feed voltage is, as the lead-acid batteries is a floating charge, telephone hangs machine about actual voltage 50V DC. When you pick up the phone, the phone is switched on, the DC circuit, phone in current, voltage drop is 7-10V, depending on the line length, phone.
Phone-hook after the current is not the same, the subscriber line, telephone and on-line exchange equipment. Usually in 20-30mA. Hanging is current should be around 5 µA.
When the bell rings, ring voltage is 75V, frequency of 16-25Hz AC voltage.
The crossbar switch hook 60V
Programmable switch-hook 48V
Ringing voltage 90V
Hang-up 48V, ring 90V, call 8V
But the value is not accurate, will the changes within a certain range. Given only general value
Local Council hanging machine DC 48V.
Ring: 20HZ, 75V above
Phone: depending on the line and telephone quality, generally between 6-12V DC
Smaller switches: DC voltage General two: 24 or 48.
Ring and when you call.
Although the voltage in the + 36V, but because of their current very small, there is no harmto people, rest assured.