VAMP 140 - Relay Protection Functions; Overcurrent Protection I>, I>>, I>>> (50;51)

VAMP Ltd Overcurrent and earth-fault relay
Technical description
VAMP 140
VM140.EN011 Vamp 24h support phone +358 (0)40 573 6316
7
2.2. Relay protection functions
2.2.1. Overcurrent protection I>, I>>, I>>> (50/51)
The three-phase overcurrent unit comprises three separately
adjustable overcurrent stages, i.e. stage I>, I>> and I>>>.
The overcurrent unit measures the fundamental frequency
component of the phase currents.
Stage I> can be configured for definite time or inverse time
operation characteristic. Stage I>> and stage I>>> have
definite time characteristic.
Figure 2.2.1-1 shows the functional block diagram of stage I>.
&
t
³1
&
&
>
t s
t r
MAX
3vIslohko
Setting I>s Delay Definite / inverse
time
Enable eventsInverse time
characteristics
Multiplier
Start
Trip
Register
event
Register
event
Im1
Im2
Im3
Block
Figure 2.2.1-1 Block diagram of the three-phase overcurrent stage I>.
Parameters of the overcurrent stages:
I>, I>>, I>>> (50/51)
Parameter: Value/unit:
Measured
value
ILmax A
Max. value of phase currents
IL1, IL2, IL3 primary values
I>, I>>,
I>>>
A
Setting value in primary
current units
I>, I>>,
I>>>
pu
Setting value as per unit
value. Setting done in xIn
DT
Operation charact./ definite
time (I>)
Curve
NI, VI
EI, LTI
Operation charact./ inverse
time (I>)
t>, t>>,
t>>>
s Operation time
Setting
values
k
Time multiplier at inverse
time (I>)