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SME2-IS - Manual - 06- 2021
FUNCTIONAL CHARACTERISTICS
The protection threshold can be enabled or disabled,
[1]
with the following defaults:
• The threshold is disabled with the setting P> = 0.4600 P
n
(8 MW), and tripping time t
P
> = 0.15 s
Operating logic
The positive tripping threshold is considered to be that in which the active component (Id) of the
current is in phase with the reference voltage.
The negative tripping threshold is considered to be that in which the active component of the current
has the opposite phase to the reference voltage.
The direction of the current is positive by convention when it is supplied from the substation to the
user, and negative when it is supplied to the substation by the generator.
When the transiting active power exceeds the set threshold P>, the threshold itself starts (Start) and
the timer starts counting. If the condition persists, when the tripping time expires (t
P
>), the threshold
trips (Trip), otherwise the threshold is reset.
Note 1 If the threshold is disabled (P> Enable = OFF) the trip command is not available but it still contributes to the internal logic
P
P>
t
t
P
>
General characteristic of the tripping time for the directional active maximum power function
(32P)
TRIP
P>
TRIP
Active power directionality
Positive active power (P>0)
Negative active power (P<0)
U
12
I
L3-d
I
L3
I
L3-q
U
12
I
L3-d
I
L3
I
L3-q
U
12
I
L3-d
I
L3
I
L3-q
U
12
I
L3-d
I
L3
I
L3-q
Power directionality conventions
Negative power P<0
Positive power P>0
CS
PC
U
G
G
CS CS
General functional diagram of the Directional active overpower function (32P)
Maximum directional active power (32P)
P
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