Analog Inputs; Introduction; Operation Principle - Hitachi Relion 650 Series Technical Manual

1MRK 511 557-UEN Rev. A
Section 3
3.1

Introduction

Analog input channels in the IED must be set properly in order to ensure correct controlled switching
operations. 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). Control and
monitoring 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 transformers and voltage transformers properly.
The availability of CT and VT inputs, as well as setting parameters are fixed for Switchsync PWC600.
The IED has the ability to receive sampled voltage and current values from one or more (up to 4)
merging units (MUs) via IEC 61850-9-2(LE) process bus. Mixed mode is possible, for example,
conventional voltage transformers and electronic current sensors via MU, or vice versa.
A reference phase AngleRef must be defined to facilitate service values reading. This analog
channel's phase angle will always be fixed to zero degrees and all other angle information will be
shown in relation to this analog input. By default, PhaseAngleRef is assigned to TRM - Channel 5,
which is used for the first reference voltage input (Source voltage L1) in the pre-configuration. If
source voltage from TRM is not available (not connected), SST would next select TRM - Channel1
(Load current), MU1-L1U (Source voltage 9-2 LE) and MU1-L1I (Load current 9-2 LE). During testing
and commissioning of the IED, the reference channel can be changed to facilitate testing and service
values reading.
Refer to
3.2

Operation principle

The direction of a current depends on the connection of the CT. The main CTs are typically star
connected and can be connected with the star point towards the object or away from the object. This
information must be set in the IED.
The convention of the directionality is defined as follows:
• Positive value of current or power means that the quantity has the direction into the object.
• Negative value of current or power means that the quantity has the direction out from the object.
For directional functions the directional conventions are defined as follows (see
• Forward means the direction is into the object.
• Reverse means the direction is out from the object.
Technical Manual

Analog inputs

Section 15 for details on the hardware interfaces of PWC600.
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Section 3
Analog inputs
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