SAGEM 3P@C
Capacitance measurement
Disconnect the tested lines from the switch, and select the capacitance measurement gear of the digital multimeter by connecting it with the external terminal, A and B lines, to measure the capacitance between Line A and Line B, that is, the capacitance C
Resistance measurement
Disconnect the tested lines from the switch, and select the resistance gear of the digital multimeter by connecting it with the external terminal, A and B lines, to measure the insulation resistance between Line A and Line B, that is, the insulation resistance R
Similarly, the loop resistance of the subscriber line can also be measured, and the way is to loop at remote end, and connect Line A with Line B shortly, and disconnect the local A and B lines from the switch; use the digital multimeter to connect the local A and B terminals, and select the resistance gear of the multimeter to read the measurement resistance, that is, the tested DC loop resistance. The table below gives the reference values of the DC loop resistance for subscriber lines with different core diameters per kilometer:
Table
Core diameter (mm) | 0.32 | 0.4 | 0.5 |
Loop resistance (Ω/km) | 470 | 280 | 190 |
In practice, it may be the subscriber line of mixed core diameters, in this case, we should give it a comprehensive consideration, the DC loop resistance of subscriber line should not be more than 1.1 kΩ. For the external measurement, some parameter index of the external lines can be tested by means of 112 test terminal.
Through the measurement of the actual subscriber line, a reference table will be given for guiding the commissioning of the ADSL service, and the details are shown in the table below:
Table
AC voltage | V | V | V |
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(VAC) |
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| 0V | 0V | 0V |
| |
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| |||
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| |
DC voltage | V | V | V |
| |
(VDC) |
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| 0V | 0V | 0V |
| |
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| |||
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Resistance | R | R | R | R | |
(Ω) | core | resistance |
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| resistance |
diameter: | 280Ω/km | >5MΩ | >5MΩ | >5MΩ | |
0.4mm |
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Capacitanc | C | C | C | C | |
e (uF) | core |
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diameter: | >0.35uF | ||||
0.4mm |
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|
Based on the above table, we can make an analysis on the line status:
Judge whether there is tap of power line by viewing the AC voltage.
Judge whether there is swinging cross by viewing the DC voltage, V
Judge the insulation of Line A and B
The open line test requires to inform users to remove all the devices on the subscriber line for measurement. C
3P@C Installation Manual
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