ABB Relion 650 Series Applications Manual page 91

1MRK 505 287-UUS B
VPolMin : Minimum polarization (reference) residual voltage for the directional function, given in %
VBase /√3.
of
IDirPU : Operate residual current release level in % of IBase for directional comparison scheme. The
setting is given in % of
measurement. The output signals, PUFW and PUREV can be used in a teleprotection scheme. The
appropriate signal should be configured to the communication scheme block.
7.2.3.3 2nd harmonic restrain
If a power transformer is energized there is a risk that the current transformer core will saturate
during part of the period, resulting in a transformer inrush current. This will give a declining
residual current in the network, as the inrush current is deviating between the phases. There is a
risk that the residual overcurrent function will give an unwanted trip. The inrush current has a
relatively large ratio of 2nd harmonic component. This component can be used to create a restrain
signal to prevent this unwanted function.
At current transformer saturation a false residual current can be measured by the protection. Also
here the 2
2ndHarmStab : The rate of 2nd harmonic current content for activation of the 2nd harmonic
restrain signal. The setting is given in % of the fundamental frequency residual current.
HarmRestrainx : Enable block of step x from the harmonic restrain function.
7.3 Thermal overload protection, two time constants
TRPTTR (49)
7.3.1 Identification
Function description
Thermal overload protection, two
time constants
7.3.2 Application
Transformers in the power system are designed for a certain maximum load current (power) level.
If the current exceeds this level the losses will be higher than expected. As a consequence the
temperature of the transformer will increase. If the temperature of the transformer reaches too
high values the equipment might be damaged:
• The insulation within the transformer will experience forced ageing. As a consequence of this,
the risk of internal phase-to-phase or phase-to-ground faults will increase.
• There might be hot spots within the transformer, which will degrade the paper insulation. It
might also cause bubbling in the transformer oil.
Busbar protection REB650
Application manual
IBase and must be set below the lowest INx> setting, set for the directional
nd
harmonic restrain can prevent unwanted operation.
© Copyright 2013 ABB. All rights reserved
IEC 61850 IEC 60617
identification identification
TRPTTR
SYMBOL-A V1 EN-US
Current protection
ANSI/IEEE C37.2
device number
49
Section 7
M15282-90 v5
IP14513-1 v4
M14877-1 v2
M15341-3 v4
85