3.1.3 Calculating settings for global base values for setting
function GBSVAL
Each function uses primary base values for reference of settings. The base values are
defined in Global base values for settings function. It is possible to include six Global
base values for settings GBASVAL functions: Global base 1 – Global base 6. In this
application, only Global base 1 is needed for defining the base for all inputs.
For transformer protection, set the parameters for the Global base values for settings
functions according to the power transformer primary rated values:
1. Set IBase to 1000 A.
2. Set UBase to 145 kV.
3. Set SBase to 251 MVA.
3.1.4 Calculating settings for instantaneous phase overcurrent
protection 3-phase output PHPIOC
Instantaneous phase overcurrent protection 3-phase output (PHPIOC) shall give very
fast fault clearance of line short circuits close to the substation.
1. Set GlobalBaseSel to 1
The settings are made in primary values. These values are given in the base
settings in Global base 1.
2. Set I>> to 600 % of IBase.
The protection shall not overreach the line and it shall not trip for short circuits
in the reverse direction.
A three-phase short circuit at the remote line end and low source impedance
gives the following fault current to the protection:
145
3
4.0 83
3.2 2.5 17.5
ph
sc
sc line
U
I kA
Z Z j j
= = = Ð °
+ + +
EQUATION2341 V1 EN
Z
sc
is the positive sequence source impedance “behind” the line and Z
line
is the
positive sequence impedance of the line.
A three-phase short circuit at the own busbar (reverse fault) gives the following
fault current to the protection:
145
3
4.0 83
3.2 2.5 17.5
ph
sc
sc line
U
I kA
Z Z j j
= = = Ð °
+ + +
EQUATION2341 V1 EN
Z
sc
is the positive sequence source impedance of the remote substation and Z
line
is the positive sequence impedance of the line.
3. Set IP>> to 600 % of IBase (6000 A primary).
Section 3 1MRK 505 291-UEN A
REQ650 setting examples
46
Application manual
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