First, the end of the cable with a breakpoint connected to the 220V line of fire, the other end to make it vacant. Move the multimeter's stalls to the AC 2V voltage block.
And then from the fault cable fire line access side, one hand clenched black table pen, red pen along the fault cable insulation layer slowly slide. The voltage at the breakpoint of the cable is about 0.445V.
When the red pen moves to somewhere, the multimeter displays a voltage drop of 1/10 or 0.04V for the normal voltage. At this point you can basically break the breakpoint in the position forward (FireWire access) 15cm.
If the shielding of the shield is not damaged, then the method can not be used
First, remove the cable around the cable has a power supply, and then break the cable connected to the line of fire, and then use the sensor pen to move vertically perpendicular to the cable, when the induction pen exchange signal disappears, you can determine the breakpoint in the detection Point, the error up to no more than 10cm.
For shorter cable test breakpoints can be used to bend the method, the cable ends were connected to the multimeter red and black table at both ends.
From the end of the cable began to bend back and forth, if the multimeter at this time off, then breakpoint on here. In accordance with this method has been detected until the breakpoint so far.
This method is to use the cable off to check the cable breakpoint. Insert the breakpoint cable into the needle, and then use the multimeter to measure the continuity.
The difference is where the breakpoint is. But the method will destroy the insulation, it is easy to use in the late cable, causing other problems.
In addition to the underground cable fault point to judge, you can use the audio detector to determine the point of failure.
For the cable length and short circuit, the decision to break the road, you can use the cable fault telemetry.
The cable generator signal generator is powered by an AC power supply, which adds a fixed cycle unipolar DC pulse to the power off, to be identified. The generator output line is connected to the cable core and the ground point or ground nail, which is disconnected from the earth, and the core is connected at the distal end to the ground point or to the ground, which conducts the pulse current, which can be identified by The meter's meter readout, the current size determined by the loop resistance, loop resistance should be as small as possible.
The sensor is a current transducer with a jaw internal dimension of 120mm. When the current flows through the test cable, the voltage is sensed in the sensor, and the voltage amplitude is determined by the current intensity, whose polarity is determined by the direction of the current.
Be sure to perform the following safety tests to avoid personal injury or damage to cable identifiers and other equipment. When using a cable recognizer, check the cable to be tested and make sure that the cable is in no power. These live parts are protected by an insulating material.