2. Specifications
MV3DB Series DB Units
ALSPA MV3000e Dynamic Braking Units
(07/06)
Page 2-4
2.5
Illustration of Ratings
This section illustrates the ability of the DB Units to absorb the energy from inertial loads
during deceleration to zero speed. For speed reductions from one speed to another (not zero)
refer to Section 3.4.
Figures 2-2 to 2-4 show the time taken to brake a given inertia from a typical speed of 1500
r/min to zero speed, for DB Units operating at 400 V, 480 V and 690 V nominal supply volts,
using the standard
Converteam
braking resistors shown in Table 2-1. It is assumed that the
braking torque during deceleration is constant.
•
If the initial speed is not 1500 r/min, the braking time to zero can be found by using the
graph to find the braking time
graph
t
for 1500 r/min and scaling by the following formula:
where
1
t
= actual braking time
2
N
= initial speed
•
Inertia is shown in kg m
2
.
1 kg m
2
= 23.73 lb ft
2
.
Figure 2-2 Stopping times from 1500 r/min at 400 V supply voltage
2
2
2
1
1500
N
t
t
graph
×
=
0
2
4
6
8
10
12
14
16
18
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
Total Inertia (kgm
2
)
B
ra
k
ing time
f
ro
m
1
5
0
0
r/min (
s
e
c
on
ds
)
MV3DB045S5
MV3DB092S5
MV3DB247S5
MV3DB391S5
