ABB Relion REQ650, Applications Manual

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Section 4 Analog inputs
4.1 Introduction
Analog input channels in the IED must be set properly in order to get correct
measurement results and correct protection operations. For power measuring and all
directional and differential functions the directions of the input currents must be
defined in order to reflect the way the current transformers are installed/connected in
the field ( primary and secondary connections ). Measuring and protection algorithms
in the IED use primary system quantities. Consequently the setting values are
expressed in primary quantities as well and therefore it is important to set the
transformation ratio of the connected current and voltage transformers properly.
The availability of CT and VT inputs, as well as setting parameters depends on the
ordered IED.
A reference PhaseAngleRef must be defined to facilitate service values reading. This
analog channels phase angle will always be fixed to zero degrees and all other angle
information will be shown in relation to this analog input. During testing and
commissioning of the IED the reference channel can be changed to facilitate testing
and service values reading.
4.2 Setting guidelines
4.2.1 Setting of the phase reference channel
All phase angles are calculated in relation to a defined reference. An appropriate
analog input channel is selected and used as phase reference. The parameter
PhaseAngleRef defines the analog channel that is used as phase angle reference.
The initially connected phase-to-earth voltage is usually chosen as PhaseAngleRef . A
phase-to-phase voltage can also be used in theory, but a 30 degree phase shift between
the current and voltage is observed in this case.
If no suitable voltage is available, the initially connected current channel can be used.
Although the phase angle difference between the different phases will be firm, the
whole system will appear to rotate when observing the measurement functions.
The phase reference does not work if the current channel is not
available. For example, when the circuit breaker is opened and no
1MRK 505 291-UEN A
Section 4
Analog inputs
61
Application manual