ABB Relion REG670, Applications Manual

Page: 326 / 780

9.1.3 Setting guidelines
The parameters for instantaneous phase overcurrent protection PHPIOC are set via the
local HMI or PCM600.
This protection function must operate only in a selective way. So check all system and
transient conditions that could cause its unwanted operation.
Only detailed network studies can determine the operating conditions under which the
highest possible fault current is expected on the line. In most cases, this current
appears during three-phase fault conditions. But also examine single-phase-to-earth
and two-phase-to-earth conditions.
Also study transients that could cause a high increase of the line current for short
times. A typical example is a transmission line with a power transformer at the remote
end, which can cause high inrush current when connected to the network and can thus
also cause the operation of the built-in, instantaneous, overcurrent protection.
Common base IED values for primary current ( IBase ), primary voltage ( UBase ) and
primary power ( SBase ) are set in the global base values for settings function
GBASVAL.
GlobalBaseSel : This is used to select GBASVAL function for reference of base
values.
Operation : Set the protection to On / Off .
OpMode : This parameter can be set to 2 out of 3 or 1 out of 3 . The setting controls the
minimum number of phase currents that must be larger than the set operate current
IP>> for operation. Normally this parameter is set to 1 out of 3 and will thus detect all
fault types. If the protection is to be used mainly for multi phase faults, 2 out of 3
should be chosen.
IP>> : Set operate current in % of IB .
IP>>Max and IP>>Min should only be changed if remote setting of operation current
level, IP>> , is used. The limits are used for decreasing the used range of the IP>>
setting. If IP>> is set outside IP>>Max and IP>>Min , the closest of the limits to
IP>> is used by the function. If IP>>Max is smaller than IP>>Min , the limits are
swapped.
StValMult : The set operate current can be changed by activation of the binary input
ENMULT to the set factor StValMult .
9.1.3.1 Meshed network without parallel line
The following fault calculations have to be done for three-phase, single-phase-to-
earth and two-phase-to-earth faults. With reference to Figure
168 , apply a fault in B
and then calculate the current through-fault phase current I
fB
. The calculation should
be done using the minimum source impedance values for Z
A
and the maximum source
Section 9
1MRK 502 071-UEN -
Current protection
320 Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual