![background image](http://html1.mh-extra.com/html/vamp/257/257_operation-and-configuration-instructions_3326944068.webp)
VAMP 257
Feeder and motor manager
Technical description
VAMP Ltd
26
VAMP 24h support phone : +358 (0)20 753 3264
VM257.EN002
impedance are equal) an ideal base angle setting would be -45
°
for forward protection and -45
°
+ 180
°
= +135
°
for reverse
protection. The angles are independent of the system frequency
within the range 16 to 70 Hz. See Figure 2.3.4-2.
When any of the three currents exceeds the setting value, the
phase angle of the power phasor is checked by taking into
account the base angle, too. If the angle is within the protected
area, the stage starts. After the operation delay the stage will
trip.
Stages I
dir
> and I
dir
>> can be configured for definite time or
inverse time operation characteristic. Stages I
dir
>>> and
I
dir
>>>> are configured for Definite Time operation
characteristic (DT).
Inverse time operation
(only for I
dir
> and I
dir
>>):
There are three ways to use the inverse time characteristics:
1.
using standard characteristics by selecting a curve family
(IEC, IEEE, etc) and a delay type (Extremely inverse, Short
time inverse, etc)
2.
selecting a curve family (IEC, IEEE, etc) and defining
parameters to the delay formula. This mode is activated by
setting delay type to ‘Parameters’, and then changing the
delay function parameters A..E.
3.
building the characteristics by setting 16 [current, time]
points. This mode is activated by setting curve family to
‘Prg1’, ‘Prg2’, or ‘Prg3’, thus there are maximum of 3
programmed curves available. The device interpolates the
values between given points with 2
nd
degree polynomes.
The following table shows which settings are effective for each
of the operation time modes: