Not an everyday standard for Damstra lab, the EN61238-1: testing methods and requirements for compression and mechanical connectors of power cables up to 36kV. In order to release a new range of cable connectors, SWA Ltd requested type tests to be performed on the largest cross section, one of the smaller cross sections and 2 in the middle of their total offering. Tests according to the EN61238-1 include heat cycle tests, short circuit tests and mechanical strength tests.
For heat cycle tests the connectors are fitted on a bare conductor and are arranged according to the test loop as shown in figure 1. Connectors are bolted to linking bars. As stranded conductors are applied, equalizers are used in the test loop to ensure a point of equipotential in a stranded conductor so the voltage drop over a specific distance can be measured. A total of 1000 heat cycles are made, bringing the reference conductor to 120°C and the connectors to at least 100°C by circulating a current. The current is created by the use of two coils in series up to a maximum of 2300A. The first heat cycle is used to define the exact current levels to meet the temperature requirements. The second heat cycle is used to define the duration of the heating and cooling period. When these characteristics are defined and approved, a control unit will execute the 1000 cycles. Temperatures are logged by the 80 channel data logger.
The project is executed in 2 phases. Phase 1 is the type test of 10mm2 and 95mm2, which started in October 2016. As a heat cycle requires 2 hours, total lead time of phase 1 was 12 weeks. After 200 cycles the short circuit tests were successfully completed at 1.8kA for the 10mm2 conductor and at 16.4kA for the 95mm2 conductor.
Both cross sections passed the type tests late December 2016. At the moment the 185mm2 and 630mm2 have been set up. The initial 2 heat cycles have been completed to define the set up settings. Soon these 2 cross sections will start their 1000 cycles which shall take at least 16 weeks to complete.
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