246
FUNCTION CHARACTERISTICS
If a binary input is designed for 74VText, for all the four thresholds the operating mode, when the 74VT
function is active may be defined:
• OFF: no action are issued by 74VT.
• Block: all the four thresholds are blocked when the 74VT external signal is active.
• Not directional: all the four thresholds are switched from directional to not directional criteria
when the 74VT external signal is active.
The 74VTint67 and
74VText67parameters may be set as OFF,Block,Notdirectionalinside
the Set \ Profile A (or B) \ Directional phase overcurrent-67 \ Common configuration menu, while the
74VText function must be assigned to the selected binary inputs inside the Set \ Board 1(2) inputs \
Binary input IN1-1...(IN1-x) menus.
Malfunctioning of the directional overcurrent elements can be avoided when VTs secondary fault
will arise (fuse or MCB tripping) by switching the overcurrent directional to non directional overcur-
rent protection.
Module
If the module principle and the one of three - 1/3 operation logic are selected, the start of any 67
threshold becomes active when the following condition are contemporaneously active:
A) For at least one phase the current (I
L1
, I
L2
, I
L3
) fundamental component overcomes the threshold
(I
PD>
, I
PD>>
,
I
PD>>>
, I
PD>>>>
).
B) The current phasor concerning the phase whereof the A) condition is located inside the angular sec-
tor defined by own characteristic angle (ThetaP>, ThetaP>>, ThetaP>>>, ThetaP>>>>) parameter,
that is the -90° ≤ (ThetaP-
a
x
) ≤ +90° (x=1, 2, 3) condition is fulfilled.
If the operation mode is switched to “not directional” (by the 74VT function), the B) condition is not
supervised (the A condition is comfortable).
After expiry of the associated operate time (t
PD>
, t
PD>>
,
t
PD>>>
, t
PD>>>>
) a trip command is issued; if inste-
ad the A) and B) conditions current don’t remain valid, the element it is restored.
If the module principle and the two of three - 2/3 operation logic are selected, the start of any 67
threshold becomes active when the following condition are contemporaneously active:
C) For at least two phases the current (I
L1
and I
L2
, I
L2
and I
L3
, I
L3
and I
L1
) fundamental component over-
comes the threshold (I
PD>
, I
PD>>
,
I
PD>>>
, I
PD>>>>
).
D) The current phasors concerning the phase pair whereof the C) condition is located inside the angular
sector defined by own characteristic angle (ThetaP>, ThetaP>>, ThetaP>>>, ThetaP>>>>) parameter,
that is the -90° ≤ (ThetaP-
a
x
) ≤ +90° (x=1, 2, 3) condition is fulfilled.
If the operation mode is switched to “not directional” (by the 74VT function), the D) condition is not
supervised and the operation logic is automatically forced to one of three - 1/3 (the A condition is
comfortable).
When the operate time (t
PD>
, t
PD>>
,
t
PD>>>
, t
PD>>>>
) is expired a trip command is issued; if instead the C)
and D) conditions current don’t remain valid, the element it is restored.
criteri-F67.ai
Operating mode and logic concerning the
phase
directional overcurrent protection - 67
1/3 2/3
YES
YES
NO
NO
OFF
Block
Block
Not directional
Not directional
OFF
67 Operating mode (Mode67)
67 Operating logic(Logic67)
Start =ON
Mode67 = I* cos (projection mode)
Logic67= 2/3 (at least two phases)Logic67= 1/3 (at least one phase)
Mode67 = I (module mode)
74VTint(ext)67
74VTint(ext)67
Start =OFF
at least two phases > threshold
at least one phase > threshold
Start =ON
XMR-D EQUIPMENT MANUAL
Ed. 2.9 - 02/2021