Plate type instrument control module PFVI401 3BSE018732R1

Plate type instrument control module PFVI401 3BSE018732R1

Plate type instrument control module PFVI401 3BSE018732R1

The settings for Distance measuring zones, quadrilateral characteristic ((ZMRPDIS) are done in primary values. The instrument transformer ratio that has been set for the analogue input module is used to automatically convert the measured secondary input signals to primary values used in (ZMRPDIS). The following basics must be considered, depending on application, when doing the setting calculations:

• Errors introduced by current and voltage instrument transformers, particularly under transient conditions.

• Inaccuracies in the line zero sequence impedance data, and their effect on the calculated value of the earth-return compensation factor.

• The effect of infeed between the IED and the fault location, including the influence of different Z0 /Z1 ratios of the various sources.

• The phase impedance of non transposed lines is not identical for all fault loops. The difference between the impedances for different phase-to-earth loops can be as large as 5-10% of the total line impedance. • The effect from load transfer together with fault resistance may be considerable in some extreme cases.

• Zero sequence mutual coupling from parallel lines. 7.9.3.2 Setting of zone 1 The different errors mentioned earlier usually require a limitation of the underreaching zone (normally zone 1) to 75 – 90% of the protected line. In case of parallel lines, consider the influence of the mutual coupling according to section “Parallel line application with mutual coupling” and select the case(s) that are valid in the particular application.

By proper setting it is possible to compensate for the cases when the parallel line is in operation, out of service and not earthed and out of service and earthed in both ends. The setting of earth-fault reach should be selected to be <95% also when parallel line is out of service and earthed at both ends (worst case).