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VAMP 257
Feeder and motor manager
Technical description
VAMP Ltd
36
VAMP 24h support phone : +358 (0)20 753 3264
VM257.EN002
2.3.8.
Stall protection (48)
NOTE!
This function is available only in motor protection mode.
The stall protection unit I
st
> measures the fundamental
frequency component of the phase currents.
Stage I
st
> can be configured for definite time or inverse time
operation characteristic.
The stall protection stage protects the motor against prolonged
starts caused by e.g. a stalled rotor. While the current has been
less than I
stop
= 10% x I
mot
and then within 200 milliseconds
exceeds I
StartMin
the stall protection stage starts to count the
operation time T according to Equation 2.3.8-1. The equation is
also drawn in Figure 2.3.8-1. When current drops below 120 %
x I
mot
the stall protection stage releases.
Equation 2.3.8-1
START
MEAS
START
T
I
I
T
=
where,
T
= Operation time
I
START
=
Start current of the motor. Default 6.00xI
mot
I
MEAS
= Measured current during start
T
START
= Maximum allowed start time for the motor
T
IM
E
C
U
RR
ENT
I
S
T
AR
T
T
S
T
AR
T
IstartMin
Figure 2.3.8-1. Operation time delay of the stall protection stage I
st
>.
If the measured current is less than the specified start current
I
START
the operation time will be longer than the specified start
time T
START
and vice versa.