Piezomagnetic tension sensor 3BSE004160R1

Piezomagnetic tension sensor 3BSE004160R1

Piezomagnetic tension sensor 3BSE004160R1

The operation of high impedance earthed networks is different compared to solid earthed networks where all major faults have to be cleared very fast. In high impedance earthed networks, some system operators do not clear single phase-toearth faults immediately; they clear the line later when it is more convenient.

In case of cross-country faults, many network operators want to selectively clear one of the two earth faults. To handle this type phenomena Phase preference logic function (PPLPHIZ) is needed, which is not common to be used in transmission applications.

In this type of network, it is mostly not possible to use distance protection for detection and clearance of earth faults. The low magnitude of the earth-fault current might not give start of the zero-sequence measurement element or the sensitivity will be too low for acceptance. For this reason a separate high sensitive earth-fault prot

General Introduction of parallel lines in the network is increasing due to difficulties to get necessary area for new lines. Parallel lines introduce an error in the measurement due to the mutual coupling between the lines.

The lines need not to be of the same voltage in order to experience mutual coupling, and some coupling exists even for lines that are separated by 100 meters or more. The reason to the introduced error in measuring due to mutual coupling is the zero sequence voltage inversion that occurs. It can be shown from analytical calculations of line impedances that the mutual impedances for positive and negative sequence are very small and it is a practice to neglect them