ADP200 • Quick installation guide - Specifications and connection
45
7.8 Braking
There are various possible types of braking:
- Internal Braking Unit
- Injection of direct current from the Inverter into the motor (D.C. braking)
There are two essential differences between the two braking methods:
- A braking unit can be used for speed reduction (e.g.: from 1000 to 800 rpm), whereas D.C. braking can only be
used for braking to standstill.
- The energy in the drive is converted into heat in both cases. This conversion takes place in a braking resistor
encased in the braking unit. With D.C. braking, the energy is converted into heat in the motor itself, resulting in a
further rise in motor temperature.
7.8.1 Braking unit (internal)
Frequency-regulated motors during the deceleration behave as generators, recovering energy that flows through the
inverter bridge, in the intermediate circuit as continuous current.
This leads to an increase in the intermediate circuit voltage.
Braking units (BU) are therefore used in order to prevent the DC voltage rising to an impermissible value. When used,
these activate a braking resistor that is connected in parallel to the capacitors of the intermediate circuit. The feedback
energy is converted to heat via the braking resistor (R
br
), thus providing very short deceleration times and restricted
four-quadrant operation.
In the standard configuration,
ADP200 drives (
≤
55kW) comprise an internal braking unit.
E
3
M
_
R
BR
BU
U
ZK
Figure 7.8.1: Operation with braking unit (circuit diagram)
Note!
When the internal braking unit is present the protection must consist of fast-acting fuses! Follow the relative assembly instructions.
A twisted cable must be used for the connection of the braking resistor (terminals BR and C or BR1 and BR2). If the
resistor includes a thermal protection device (Klixon), this must be connected to the "External fault" input of the drive.
Table 7.8.1: Technical data of the internal braking unit
Size
I
rms
(A)
I
pk
(A)
R
br
(
Ω
)
2075
8.5
12
68
2110
15.5
22
36
3150
22
31
26
3185
26.3
37.2
18
3220
26.3
37.2
18
4300
47
67
12
4370
47
67
12
4450
57
80
10
5550
5S550
5S750
71
100
8
I
rms
Braking unit rated current, duty cycle = 50%
I
pk
Peak current that can be delivered for max 60 seconds
R
br
Minimum braking resistance value
Table 7.8.2: Braking unit intervention threshold
v
br
@ 480 V
v
br
@ 460 V
v
br
@ 400 V
ON
OFF
ON
OFF
ON
OFF
800 Vdc
790 Vdc
768 Vdc
758 Vdc
670 Vdc
660 Vdc
Note!
For the combination of recommended braking resistors
refer to chapter 5.4
.