VAMP Ltd
Feeder and motor manager
Technical description
VAMP 257
VM257.EN002
VAMP 24h support phone : +358 (0)20 753 3264
53
20
30
50
7
0
10
1
.
00
1
.
20
0
.8
0
0
.6
0
0
.
70
0
.9
0
1
.
10
40
6
0
8
0
k
(
°
C)
AM
B
k
40
k
0
Figure 2.3.15-2. Ambient temperature correction of the thermal overload
stage T>.
NOTE!
Ambient temperature correction is only available in motor
protection mode.
Ambient temperature correction for the maximum allowed
continuous current used by the thermal overload stage. The
slope is defined by the user giving the relative motor currents
at ambient temper40
°
C and +70
°
C. The default
values are I
MAX40
= 100% and I
MAX70
= 78%.
The device is updating the thermal image continuously. If the
calculated temperature exceeds the given alarm limit
Θ
ALARM
the stage gives out a start signal. When the temperature
exceeds the trip level
Θ
TRIP
the stage activates the trip signal.
The start and trip signals are controlling the output relays via
the user configured output relay matrix. The start signal is not
released until the temperature is
Θ
DEADBAND
below
Θ
MAX
. The
temperature dead band
Θ
DEADBAND
is 10 % x
Θ
TRIP
.
Whenever the current is below I
STOP
the motor is supposed to
be stopped and a longer time constant is used for modeling the
temperature. The maximum current for a stopped motor Istop
is 10 % x Imot.
NOTE!
If the motor manufacturer gives a t6x value instead of
τ
, the
τ
can be calculated using Equation 2.3.15-1 assuming that the
t6x is given for a motor in normal operating temperature. If the
t6x is given for a cold motor then Equation 2.3.15-2 should be
used.
Equation 2.3.15-1
X
t
6
71
⋅
=
τ
Equation 2.3.15-2
X
t
6
5
.
35
⋅
=
τ