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VAMP Ltd
Motor protection relay
Technical Description
VAMP 150
VM150.EN005
Vamp 24h support phone : +358 (0)20 753 3264
15
If the motor manufacturer gives a t
6x
value instead of
τ
, the
τ
can be calculated using equation 2.2.3.-2 assuming that the t
6x
is given for a motor in normal operating temperature. If the t
6x
is given for a cold motor then equation 2.2.3.-3 should be used.
Equation 2.2.3.-2
x
t
6
71
⋅
=
τ
Equation 2.2.3.-3
x
t
6
5
.
35
⋅
=
τ
The trip level is determined by the maximum allowed
continuous current I
MAX
. This current corresponds to the 100 %
temperature
Θ
TRIP
i.e. the heat capacitance of the motor. I
MAX
depends of the setting k and setting
Θ
AMB
, I
MAX40
and I
MAX70
.
MOT
MAX
I
k
k
I
⋅
⋅
=
Θ
The value of ambient temperature factor k
Θ
depends on the
setting
Θ
AMB
, I
MAX40
and I
MAX70
. See Figure 2.2.3-1.
Figure 2.2.3-2. Behaviour of VAMP 150 T> protection stage