6
Version 1.0.6
5.3
DHC-124
D
IFFERENTIAL
H
AND
-
COIL
S
ENSOR
The SR-101 includes a DHC-124 Differential Hand-coil Sensor for fault location. This sensor is designed to
reduce outside electrical interference, and optimized to virtually eliminate tone beyond the cable fault.
The DHC-124 is connected to the DAP connector on the right of the SR-101.
5.4
O
THER
C
OIL
S
ENSORS
A phone plug connector on the right side of the SR-101 allows using other compatible probes with the SR-
101. Probes not manufactured by AALogic may not be compatible.
5.5
ST-101
TONE TRANSMITTER
A suitable tone transmitter is required and the SR-101 is compatible with other tone transmitters capable
of sending compatible frequencies with sufficient power to be detected by the SR-101. The ST-101 is a
high-powered signal transmitter capable of sending tone through a 100,000 ohm resistive fault to be
detected by the SR-101 receiver.
The transmitter has adjustable frequency and power settings. Higher power settings should be used for
higher resistance faults. The lower frequencies have a reduced chance of tone carry-over beyond the
fault. Lower power settings are less likely
to “dry”
the fault during the locate process. The 4 kHz frequency
will radiate further and is typically chosen when the fault resistance is high.
It should be noted that various fault conditions and cable make-up determine the maximum locatable
fault resistance. A short condition, the most difficult to find due to the pair twist, requires greater
current to be detected from the outer sheath. Faults located in the center binder groups of cables are
more difficult to locate than pairs near the sheath.
5.6
L
OCATING THE
F
AULT
A signal transmitter, such as the ST-101, must be connected to the cable pair as discussed previously. The
frequency and power settings should be selected to begin the locating procedure. The frequency and/or power
may need to be adjusted to improve the signal reception. Refer to the transmitter documentation as needed.
1.
Prepare the SR-101 by connecting the DHC-124 hand coil or another appropriate sensor to the SR-101.
2.
Turn on the SR-101 and select Locate using the keys from the Home screen.
3.
Select the frequency matching the transmitter frequency.
4.
Place the sensor near the cable and adjust the Gain and Volume for an adequate signal indication on the
SR-101 and from the speaker/earphone. The graph signal should be maintained between 20% and 80%.
5.
Move the sensor along the cable while monitoring the screen graph and audible tone. Adjust the Gain
and Volume as needed.
Note: The cable pair and group are twisted inside the cable. This means the pair may be on the top, bottom,
or middle as the probe is moved along the cable. It is normal for the signal indication to rise and fall before
and after the fault. The fault location is determined by higher average signal peaks before the fault than
after the fault for shorts, grounds, and crosses. The average peaks are higher after a split than before the
split.
The average signal may also increase as a splice case is approached. This is due to the lack of sheath
shielding at the case and the separation of the pair groups during splicing. The position of the pair in the