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Rating
v
I
t
t
D
i
Figure 1: Movement cycle: Profile for energy assessment
This profile with velocity (v) and motor current (I) is also used for rating
the motor and the braking resistor. The deceleration segment to be
considered is labeled D
i
.
Calculation of the energy at constant deceleration:
The total inertia (J
t
) must be known.
J
t
with:
J
t
= J
m
+ J
c
J
m
: Motor inertia with or without holding brake
J
c
: Load inertia
The energy for each deceleration segment is calculated as follows:
2π
n
i
2
60
ω
i
2
= E
i
=J
t
1
2
J
t
1
2
Units: E
i
in Ws (wattseconds), J
t
in kgm
2
, ω in rad and n
i
in min
-1
.
See the technical data for the energy absorption E
var
of the devices
(without consideration of an internal or external braking resistor).
In the next calculation steps, only consider those segments D
i
, whose
energy E
i
exceeds the energy absorption of the device (see chapter
"2.2 DC bus data"). These excess energies E
Di
must be diverted by
means of the braking resistor (internal or external).
E
Di
is calculated using the following formula:
E
Di
= E
i
- E
var
(in Ws)
The continuous power P
c
is calculated for each machine cycle:
LXM32
3 Engineering
Common DC bus
23
MNA01M001EN, V1.01, 08.2014