EXFO CableSHARK P3 VF/DSL Cable Qualifier - Manual (Page 249)

CableSHARK P3 User Guide
237
Section 16 K-Test
16.1 K-Test
The K-test or Kupfmuller test can be used to find the approximate distance to a resistance fault when both
wires in a single pair are faulted at the same place and a separate good pair is not available (see RFL Test).
T
R
GND
Faulty wire
R1
R2
Faulty wire
Reference wire
NOTE: R1 and R2 are faulted resistances
F IGURE 16.1A – S HORT BETWEEN T IP AND R ING TO G ROUND
Additional requirements for use of this test are as follows (but don’t worry, the CableSHARK will also look for
these and make the decision for you):
• One fault must be at least twice as “heavy” as the other fault (e.g., 5kΩ is twice as “heavy” as 10kΩ).
I.e. R1 > 2 x R2 or R2 > 2 x R1
• The sum of both faults must be at least 100 times the loop resistance (for instance, if the loop resistance
is 50W, the “lighter” fault must be 5kW or greater). I.e. R1 + R2 > 100 * Loop resistance
16.2 Setting up a K-test
16.2.1 Disconnecting the Station Battery and the Customer
Before a K-test can take place, the circuit that is to be tested must be disconnected from the CO station
battery and from the customer. The K-test is an end-to-end test meaning that the CableSHARK is placed at
one end of the circuit (typically on the CO side of the circuit) and a strap is placed on the customer side of
the circuit.