12
CABLE FAULT TESTER
The CFT-35 Cable Fault Tester is for
use only with two stick voltmeters
for testing leakage
current in underground
primary voltage cables.
The CFT-35 can be used
on underground cables with grounded neutrals with a maximum line-to-ground voltage of
21.1kV or maximum line-to-line voltage of 36.6kV. Operation at higher voltages may
damage the CFT-35 and provide erroneous test results.
The CFT-35 is used with a voltmeter/phaser for testing installed or repaired underground
cable prior to energizing it. Only cable with extruded dielectric such as rubber or polyethylene
can be tested with the CFT-35. Using the CFT-35 on paper insulated cable may provide
erroneous test results caused by higher leakage currents typical for this type of cable.
The CFT-35 contains a high voltage rectifier and is connected to test underground
primary cable as shown in this circuit:
In practice, the CFT-35 rectifies the high voltage from the source, usually a transformer
primary, and charges up the cable, shown as a capacitor above. When a connection is
first made, the DC from the CFT-35 will charge up the cable capacitance through the
resistors in the meter sticks. If the cable is good, current will stop flowing when the
cable is charged up. If the cable is not good, the cable will not charge and current will
continue to flow, as indicated by a higher meter indication.
The following equipment is required for testing cable with a CFT-35:
1) An HD Electric two-stick voltmeter/phaser.
2) The CFT-35 Cable Fault Tester.
3) For deadfront applications, ASP bushing probe(s) or, for live front
applications, GCP-1 probe(s). An EA-15/25 elbow probe may also
be used for deadfront applications.
4) For deadfront applications, a feed-through bushing may also be used.
PROBES AND ACCESSORIES continued
CFT-35
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