Mess- und Ortungstechnik Measuring and Locating Technologies

SPG 40 and Cable Test Van Compact City INFO Version 01

- as of 25. Aug 2005 -

Information

Leitungsortung Line Locating

Rohrleitungsnetze Water Networks

Kommunikationsnetze Communication Networks

Elektrizitätsnetze Power Networks

Compact fault location system for low and medium voltage cables

SPG 40 and Compact City

SPG 40 and cable test van version Compact City Compact fault location system for low and medium voltage cables Even prior to the regulation of the market for electricity, the electricity supply companies carried out comprehensive restructuring and cost-reduction measures. In the process, the existing equipment for cable testing and fault location was largely decentralised, older test equipment was disposed of and not replaced with new equipment. In particular, new investment in cable measurement vehicles was significantly reduced. Network operators now require small, very flexible measurement systems, which can be used in inner city areas with narrow pedestrian zones and minimal parking spaces and which can even be used in poorly accessible locations in underground car parks. SebaKMT's response to this was to develop a compact, universally useable test and fault location system - the SPG 40 (Fig. 1).

Fig. 1 Compact City in a small vehicle The Technical Challenge The classical high voltage technology in cable test and fault location systems is based on 50 Hz, high voltage generators with corresponding rectification units. The disadvantages of this technology are, apart from the high weight, above all the secondary technology, to implement automated operation and control. Various fault location tasks such as locating sheath faults, should be carried out without damaging the cable, if possible. This requires control of the output current, which is not possible with 50 Hz transformer technology. The technology should also be implemented with minimal weight and should need little space. On the basis of a powerful, electronic, switching power-supply and an optimised cascading circuit, a high voltage generator was developed which feeds all measurement processes via specially developed system switches.

The parameters for a universal fault location system are dimensioned to suit the supply voltages of the cable network concerned. Working together with a European manufacturer of high voltage impulse capacitors, particularly compact impulse capacitors have been developed with a high energy density. These enable the new measurement system to be universally configurable. They allow particular customer requests to be met for an optimal modification of the system to the characteristics of network concerned. The Solution

Fig. 2 SPG 40 a compact & powerful test and fault

location system The SPG40 can be built as portable equipment with an integrated VGA display or, it can be produced to be built-in with a separate control unit (Fig. 2; Fig. 3)

Fig. 3 Compact City the way it is installed in a vehicle

SPG 40 and Compact City

Fig. 4 Control units of the SPG 40 and reflectometer

T 30-E For safe operation of the SPG 40, all safety features in the “large" cable test vehicle have been further developed with modern technology and provide the user with an easy to use system and absolute safety when using it. The ease of use extends to the safe to touch, high voltage, coaxial plugs in the system (Fig. 5).

Fig. 5 SPG 40 with a cable reel module, built into a

Citroen Berlingo In the SPG 40, on the basis of a graphical display, all known measurement processes have been implemented with intuitive operation. The Easy Go operating philosophy of SEBAKMT equipment and systems enables even inexperienced users to safely and efficiently carry out cable checks and fault location. In the main menu (Fig. 6) the SPG 40 measurement processes can be selected.

Fig. 6 Main menu for the measurement process In the operational mode Testing both an insulation measurement (Fig. 7) as well as the evaluation of the cable under test are possible via measurement of the leakage current.

Fig. 7 Insulation measurement up to 5 kV or cable test up

to 40 kV DC Under the Prelocation menu, the ARM (arc reflection measurement), ICE (current coupling) and Decay (voltage coupling) processes can be selected. The mostly used ARM process is implemented in the proven ARM choke technology, to couple the impulse process to the object under test. With this, even with faults at large distances or for cables with faults which are hard to ignite, successful location using an arc is possible After selecting the desired impulse voltage level, the charging voltage and single shot trigger are entered (Fig. 8).

SPG 40 and Compact City

Fig. 8 ARM prelocation in the SPG 40 As already mentioned, the SPG 40 is made into a complete fault location system with the addition of the modern, portable T 30-E reflectometer. In this combination, the user has access to an extensive automation of the measurement procedure. For example in the "ARM Quickstep" mode, only 3 steps are necessary from the operator to get the prelocation result. Cable faults are then pinpointed classically with the acoustic field method or, if the fault situation warrants it, with the step voltage process. For the step voltage method, the SPG 40 feeds a pulsed dc voltage with controllable output current to the object under test. This avoids the possibility of the fault location drying out and the damage of adjacent cables, as well as a significant safety aspect, the step voltages resulting are controlled. Due to the modular impulse voltage levels the SPG 40 can be optimally configured to the voltage levels of the customer's network. The following impulse voltage levels are available in the portable version with a pulse energy of 1000 Ws and in the Compact City even up to 2000 Ws as an option: 12.5 kV / 25 kV 16 kV / 32 kV 8 kV / 12.5 kV / 25 kV 8 kV / 16 kV / 32 kV 4 kV / 12.5 kV / 25 kV 4 kV / 16 kV / 32 kV

Fig. 9 Acoustic field method to pinpoint the location of cable faults

Summary The SPG 40 is a universally useable, compact, low weight and modular system. The system can be used portably and can be built in very ergonomically, even into small vehicles. Apart from the very flexible impulse voltage levels, the most important parameters are: Insulation measurements 1000 V / 5000 V DC testing up to 40 kV Automatically determining breakdown

voltage Burning 0 ... 8 kV with 700 mA Burning 0 ... 20 kV with 100 mA Test and locating of cable sheath faults

with step voltage of 0 ... 5 kV and 0 … 10 kV

Prelocating methods ARM, ICE, Decay

Author: Dr.-Ing. Frank Petzold

Technical general manager SebaKMT Mess- und Ortungstechnik GmbH

© 2005, Seba Dynatronic GmbH

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