IG-267-EN versión 01; 07/04/2017
16
Applications
General Instructions
ekor
.rpa
2.5. Automatic transfer
The automatic transfer of lines with circuit-breakers
minimises power outages in loads fed by transformer or
switching substations with more than one incoming line,
thereby improving continuity of service.
Under normal conditions with voltage present on two
possible incoming lines, the switch selected as preferred
remains closed and the reserve one is opened. A voltage
drop in the preferred line will cause the switch of this line
to open and the reserve switch to close afterwards. Once
normality has been re-established in the preferred line, the
inverse cycle is performed, and the system returns to its
initial status.
Figure 2.5.
Automatic transfer
2.6. Detection of phase with earthing
In networks with isolated or resonant earthed neutral, the
fault currents are very low. In the event of a fault in a system
of this type, the fault current may not reach the calibrated
threshold for overcurrent protection, and therefore this
fault may not be detected.
Function 59 is used instead of programmed logic for
detecting this type of fault, analysing both the installation’s
neutral voltage and its current.
Figure 2.6.
Detection of phase with earthing
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