The PC software package of the L2G/CR system is called LocalDef. This paragraph supplements the general presentation on the L2G.
The LocalDef software package is accessible with two different icons: one for the L2G/CR Master LocalDef software and the other for the L2G/CR Remote LocalDef software. The latter is only used by the remote station during current balance measurements.
The L2G/CR Master LocalDef software and the L2G/CR Remote LocalDef software are integrated software, for the Windows 3.1x environment or the Windows 95 operating system, written in C++. The L2G/CR Master software implements a Paradox run-time for database treatments. Additional software modules (firmware) written in C are embedded in the BI and TAM.
All individual measurements are stored on disk before they are reduced. Additional data reduction is always made on the stored data, and can therefore be repeated at will, using various data or parameter values as needed.
The L2G/CR Master software includes a data-base editor:
for editing current versus time profiles, used to specify the current sourced by the TAM during measurements ;
for editing the parameters of the cable sections (per-unit length resistance, etc);
for editing the parameters of the repeaters, namely the voltage versus current characteristic of each repeater (the figure 1 below shows this editor);
for editing the cable station databases;
for editing repair records.
Fig. 1: A LocalDef display used for editing repeater data
The L2G/CR Master software provides full control of data acquisition parameters, and their storage for later use. The figure 2 below shows an acquisition set-up windows. In this example, the current versus time profile is contained in the resmeasn.prf file. Once the link is specified (the TAT 12 cable in the example of figure 2), the maximum current value for each polarity stored in the cable station database will override any conflicting current value in the profile file. This is one of the many safety feature of the L2G/CR
Fig. 2: The acquisition set-up windows
The computation of fault location is automated and DC fault localizations may be performed using one of three methods. For each method, the fault location calculation implements high performance algorithms. Some fault location algorithms parameters may be modified by the user, but all of them have default values, so that no expertise is required from the operator.
Fig. 3: A LocalDef display showing a fault location result
The figure 3 shows a fault localization result, expressed in kilometers from the station where the measurement are made. Note that this "station" could be a cable ship. The "play-back windows" in this figure shows the current versus time that was used for this fault location. Please note that the current rate of rise is controlled by the L2G/CR, so that repeaters are not stressed by sudden current variations.
Note finally that fault location results are stored with the data acquisition parameters, for easy documentation of the work performed by the operator.
The hardware of the L2G includes a PC, a TAM and a BI, and various accessories. This paragraph gives more information on the TAM and the BI.
Three different TAM models are available. They only differ in their power-feeding capabilities:
L2G/CR/3125A and L2G/CR/6250A systems have a single-unit TAM, that can deliver up to 5 kW of DC power. The L2G/CR/6250B has a two-unit TAM, which can deliver up to 10 kW of DC power.
Fig. 4: the TAM unit of a L2G/CR/6250A fault location system
DC power supply:
| L2G/CR/3125A |
Regulated current: 0 mA to 1600 mA (two ranges)
Voltage limitation from 5 V to 3125 V
|
| L2G/CR/6250A |
Regulated current: 0 mA to 800 mA (two ranges)
Voltage limitation from 5 V to 6250 V
|
| L2G/CR/6250B |
Regulated current: 0 mA to 1600 mA (two ranges)
Voltage limitation from 5 V to 6250 V
|
Stability of current: < 0.05 % of the range value.
The TAM may be controlled, including change of polarity, from the front panel or by a remote control fiber optic link to the BI.
The TAM perfoms automatic cable discharge at limited current.
The rate of rise and rate of fall of the current may be limited to 13.2 mA/s during measurements.
Measurements:
Current measurements: three ranges simultaneously sampled.
Voltage measurements: three ranges simultaneously sampled.
Voltage and current accuracy: better than 0.05 % of the range value.
Three meters on the front panel (current, voltage, output monitor).
Max. sampling rate: 10 voltage and simultaneous current measurements per second.
Safety:
Electronic circuit-breaker in case of excessive current (protection of the cable) with independant triggering level for each polarity.
Effective grounding of the TAM envelope.
Unlimited isolation between the CDC and the TAM for operator safety in the (unlikely) case of internal breakdown.
Special
high voltage connector and receptacle for connection to the cable.
A safety loop system inhibits the DC power in case of disconnection.
Fig. 5: the BI unit
General:
CE marking for compliance with the EMC directive and the low voltage directive (safety).
AC power supply for the TAM: 3-phase 400 V nominal (342 V to 440 V), 50 Hz or 60 Hz, 6000 W. Other voltages are available upon request.
Dimensions of a single-unit TAM:
- width = 19" (i.e. 483 mm),
- height = 6 U (i.e. 265 mm),
- depth = 620 mm.
Weight of a single-unit TAM: 44 kg.
AC power supply for the BI: 1-phase 230 V nominal (198 V to 264 V), 50 Hz or 60 Hz, 10 W. Other voltages are available upon request.
Dimensions of the BI:
- width = 221 mm,
- height = 115 mm,
- depth = 255 mm.
Weight of the BI: 2.3 kg.
