The L2G and telecommunication operators

Table of contents

State of the art in DC Fault location
How much experience is there with the L2G ?
Commercial informations

1. State of the art in DC Fault location

     DC fault location is sometimes the best way, or the only way to get an accurate fault location. Automatic DC fault location is already implemented by several operators. Other operators still rely on manual measurements (for instance done directly with the PFE) and the manual implementation of fault location tables. These manual techniques are prone to human errors, and for difficult cases are expected to give at best coarse fault location estimates. Note that manual and automatic DC fault location require accurate and reliable cable reference data.

     Other major operators are expected to switch to automatic fault location, which will bring :

• accurate automatic DC fault location (resistive or capacitive) from a single station, in case of cable breaks, shunt faults or open faults,
• the possibility of automatic current-balancing measurements for shunt faults.

     Up to November 1998, 17 units of L2G systems have been delivered. We believe the L2G is a real need for new and existing subsea cable systems. It is also needed for optical cable systems complying with optical path fault location technique specifications. Please note that the L2G is implemented both in cable stations and on board cable ships.

2. How much experience is there with the L2G ?

     The concept of the L2G was defined by France Telecom. France Telecom and Excem started the development of the L2G series of fault location systems in 1993. The delivery of the series-produced equipments for BT and France Telecom began in 1996.

     The system was thoroughly tested starting April 1995, and a prototype was implemented on several cable systems in Europe. Subsequent tests, performed as from september 1996, implemented the latest version of the L2G (TAM 3125A rev. 03 or TAM 6250A rev. 03 and version 2.0x of the LocalDef software).

     The following list summarizes the implementations of the L2G/CR we are aware of :

1. Thorough acceptance test (in our laboratory), including fault location with an added random noise and a dummy fault including a portion of real optical cable in a sea-water filled pool. Implementation carried out by France Telecom and Excem in April 1995.
2. Measurements on TAT 6 (analog cable) at St Hilaire de Riez (France). Implementation carried out by France Telecom and Excem on May 3, 1995.
3. Measurements on TAT 12F (an Alcatel S5000 optical cable) at Penmarch'(France). Implementation carried out by France Telecom and Excem, on June 7, 1995.
4. Measurements on TAT 12 (optical cable) at Land's End (U.K.). Implementation carried out by FT, BT, and Excem, on July 8, 1995.
5. Measurement on Ariane 1 (analog) at Marseille (France). Implementation carried out by France Telecom, in 1995.
6. Measurement on Continent-Corse 3 at Marseille (France). Implementation carried out by France Telecom, in 1995.
7. Measurements on TAT 8 at Penmarch' (France). Implementation carried out by Excem and France Telecom, on January 19, 1996.
8. Measurements on Tagide 2 at Penmarch' (France). Implementation carried out by Excem and France Telecom, on December 10, 1996.
9. Measurements on TAT 13 at Penmarch' (France). Implementation carried out by Excem and France Telecom, on March 20, 1997.
10. Measurements on TAT 12F at Land's End (U.K.). Implementation carried out by BT, on March 27, 1997.
11. Measurements on TAT 12 at Land's End (U.K.). Implementation carried out by BT, on June 6, 1997.
12. Measurements on Ariane 2 at Marseille (France). Implementation carried out by France Telecom, in July 1997.
13. Implementation on Atlantis (analog) at Dakar (Senegal). Implementation carried out by Excem and Sonatel, as from of November 28, 1997.

     Note that in Dakar, an L2G/CR/6250A system was implemented as a back-up power supply, and was therefore continuously used by Sonatel from the end of acceptance tests to the decommissioning of Atlantis.

     As can be seen from this list, L2G has been implemented on various cables. When reliable cable reference data is available for the cable under test, the fault location results are extremely good. More information may be obtained from Excem on some of these implementations (implementations for which the station's operator authorizes the disclosure of measurement results). After 1997, we have (of course) not kept track of all measurements performed with L2G systems !

3. Commercial informations

     The November 1998 list price of the L2G/CR/3125A and L2G/CR/6250A systems is 67,248 Euros, and the current list price of the L2G/RL system is 28,138 Euros. Note that these prices apply to F.O.B. deliveries (that is to say shipment, insurance, etc not included), PC not included, without on-site installation, commissionning and training services. This price is offered for sales according to our General terms of Sale.

     Please note that the L2G being a transportable system, fully factory tested with individual automatic tests and individual operational implementation on dummy cables, installation and commissionning may not be needed. A training is usually a good idea.

     Of course, we offer these services, and others special services like shipboard installation.

     There is a strong demand for accurate automatic DC fault location systems, especially for new submarine cable systems. Many potential customers are enthousiastic about the L2G/CR transportability, and its back-up power supply capability.

     For technical or commercial inquiries concerning the L2G, please contact:

Frédéric Broydé
Fax number: 33 1 34 75 13 66  Phone number: 33 1 34 75 13 65
e-mail: webmaster@eurexcem.com
address: Excem
12, chemin des Hauts de Clairefontaine
78580 Maule    France