Section 3 Analog Inputs; Introduction; Operation Principle - ABB REG650 Technical Manual

1MRK 502 034-UEN -
Section 3
3.1
3.2
Technical Manual
Analog inputs

Introduction

Analog input channels are already configured inside the IED. However the IED has
to be set properly 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 properly. Measuring and protection
algorithms in the IED use primary system quantities. Set values are done in
primary quantities as well and it is important to set the data about 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 PhaseAngleRefmust be defined to facilitate service values reading.
This analog channels phase angle will always be fixed to zero degree 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.

Operation principle

The direction of a current to the IED depends on the connection of the CT. The
main CTs are typically star connected and can be connected with the star point to
the object or from the object. This information must be set to the IED.
Directional conventions for current or power, for example
• Positive value of current or power means quantity direction into the object.
• Negative value of current or power means quantity direction out from the object.
Directional conventions for directional functions (see figure 2)
• Forward means direction into the object.
• Reverse means direction out from the object.
Section 3
Analog inputs
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