P54x/EN ST/La4 Settings
(ST) 4-16
MiCOM P543, P544, P545, P546
ST
Setting range
Menu text Default setting
Min. Max.
Step size
Digital Filter Standard Standard or Special Application
Setting to enab
the default sett
le (activa ard’ or ‘Spec re
ing and s pplied in the majority of applications. It is only the case
s may become very distorted by non-fundamental
ssary to avoid transient over-reach. In such system
ns’ setting sho applied.
te) ‘Stand
hould be a
ial Application’ filters. ‘Standard’ filters a
when the fault currents and voltage
harmonics that extra filtering is nece
conditions the ‘Special Applicatio uld be
CVT Filters Disabled Disabled, Passive or Active
Setting that accommodate pe of voltage nt
preserve sub-cycle operating time whenever possible.
isabled’ as
n, the ‘CVT Filters’ should be set to ‘Active’.
Trip time ase prop bcycle up to S R = 2, gradu R
small up to SIR of 30. For such applications, he
s the SI ll take margi ak
(exceeds the relay’s SIR setting).
s the ty transformer being used to prevent transie
over-reach and
In case of conventional wound VTs, the transients due to voltage collapse during faults are
very small and no extra filtering is required, therefore the setting should be ‘D
per default.
For a CVT with active Ferro resonance damping, the voltage distortions may be severe
and risk transient over-reach. For that reaso
s incre
up to 30).
ortionally (su I ally lengthening for SI
For a CVT with passive Ferro resonance damping, the voltage distortions are generally
‘CVT Filters’ should be set ‘Passive’. T
nally longer to trip if the infeed is werelay calculate R and wi
SIR Setting 30 5 60 1
Setting that determines whe ng will b e
relay will marginally slow down, as otherwise
k of ch.
n extra filteri e applied. If on fault inception th
calculated SIR exceeds the ‘SIR Setting’ the
there would be a ris over-rea
This setting is visible only when ‘CVT Filters’ is set to ‘Passive’.
Load Blinder Disabled Disabled or Enabled
Setting used to activate r turn off (disa
Load blinders, when enabled, have two main ses: to prevent tripping due to load
ition and detect very slow moving power swings.
(enable) o ble) load blinders.
purpo
encroachment under heavy load cond
Z< Blinder Imp 15/In Ω 0.1/In Ω 500/In Ω 0.01/In Ω
Setting of radius of under-impedance circle.
Load B/Angle 45° 15° 65° 1°
Angle setting for the two er lines boundary or blind with the gradient of the rise fall with
respect to the resistive axis.
Load Blinder V< 15 V 1 V 70 V 0.5 V
Load blinder phase to ground under-voltage setting that overrides the blinder if the
in the se falls be s blinding of
e phase vol etting).
measured voltage
phase-phase loops wh
affected pha
re the phase-
low setting. Also override
tage falls below √3 x (V< s
Dist. Polarizing 1 0.2 5 0.1
The setting defines the composition of polarizing voltage as a mixture of ‘Self’
‘Memory’ polarizing voltage. ‘Self’ polarized voltage i
and
s fixed to 1pu and could be mixed
1
m
oltag g more ‘Mem ge ce e
with ‘Memory’ polarizing voltage ranging from 0.2pu up to 5pu. The default setting of
means that half of the polarizing voltage is made up from ‘Self’ and the other half fro
clean ‘Memory’ v e. Addin ory’ volta will enhan the resistiv
coverage of Mho characteristics, whose expansion is defined as:
Mho expansion = [(Dist. Polarizing)/ (Dist. Polarizing + 1)] x Zs
Where Zs is the source impedance.
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