ABB RELION REX640 Technical Manual page 1073

Protection and control

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Table of Contents

1MRS759142 F

Table 1010: Special conditions

U3P connected to real meas-

Improper analog channel configuration causes a validation error if the analog

channels are not completely configured or they do not match with certain settings.

For troubleshooting, check the contents of this chapter and also the preprocessing

blocks in this document. The configuration can be written to the protection relay

once the mismatch is corrected.

Operation principle

The function can be enabled and disabled with the

corresponding parameter values are "On" and "Off".

The operation of DQPTUV can be described using a module diagram. All the

modules in the diagram are explained in the next sections.

Figure 599: Functional module diagram

Under voltage detection

Under voltage detection compares the fundamental frequency component of all

three phase-to-phase voltages with the set

phase-to-phase voltages are lower than the set

voltage detection module sends an enable signal to the Timer indicating an

undervoltage condition at the grid connection point.

Reactive power monitoring

This module calculates and monitors the reactive power based on positive sequence

current and voltage. The use of a positive sequence component makes the

determination of power insensitive to a possible asymmetry in current and voltages.

Technical Manual

The function can work with any two phase voltage channels

connected but it is recommended to connect all three volt-

age channels.

Voltage start value . When all three

Voltage start value , the Under

Protection functions

Operation setting. The