PERFORM LOOP DIAGNOSTIC TESTS
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Chart 1
PERFORM LOOP DIAGNOSTIC TESTS
APPARATUS:
01
Volt-Ohmeter
(VOM)
l
1
77 Cable
Analyser
or
eqUiValent
STEP PROCEDURE
FOREIGN VOLTAGE TEST
1
Set the VOM range switch to a scale 60 Vdc/Vac or more.
2
Connect the VOM test probes to the loop at the line card or distributing frame.
3
Measure the dc and ac voltage between the following points under no-load conditions.
l T and R
l T and GND
l Rand GND
Requirement: Voltage readings should be less than 1
Vdc/Vac.
INSULATION RESISTANCE TEST
1
Set the VOM range switch to OhmX1O.OOO and adjust the meter to zero.
2
Connect the VOM test probes to the loop at the line card or distributing frame.
3
Measure the resistance between the following points under no-load conditions.
l T and R
l T and GND
l R and GND
Requirement: Resistance readings should be greater than 10
MOhm.
DC CONTINUITY TEST
1
Short circuit the T and R at the far end.
2
Using the VOM. measure the resistance between the
T
and R.
Requirement: Resistance measurement should be approximately equal to the
calculated loop resistance per DP1002.