External Braking Resistor; Thermal Protection Circuit For The Braking Resistor - Emerson Unidrive M702 User Manual
Universal variable speed ac drive for induction and permanent magnetmotors
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- Getting started manual (72 pages) ,
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- Installation manual (120 pages)
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Safety
Product
Mechanical
information
information
installation
4.10.2
External braking resistor
Overload protection
When an external braking resistor is used, it is essential that
an overload protection device is incorporated in the braking
resistor circuit; this is described in Figure 4-18 on page 68.
WARNING
When a braking resistor is to be mounted outside the enclosure, ensure
that it is mounted in a ventilated metal housing that will perform the
following functions:
•
Prevent inadvertent contact with the resistor
•
Allow adequate ventilation for the resistor
When compliance with EMC emission standards is required, external
connection requires the cable to be armored or shielded, since it is not
fully contained in a metal enclosure. See section 4.12.5 Compliance with
generic emission standards on page 74 for further details.Internal
connection does not require the cable to be armored or shielded.
Minimum resistances and power ratings for the braking
resistor at 40 °C (104 °F)
Table 4-19 Braking resistor resistance and power rating (200 V)
Minimum
resistance *
Model
Ω
03200050
03200066
20
03200080
03200106
04200137
18
04200185
05200250
16.5
06200330
8.6
06200440
07200610
6.1
07200750
07200830
4.5
08201160
08201320
Table 4-20 Braking resistor resistance and power rating (400 V)
Minimum
resistance *
Model
Ω
03400025
03400031
74
03400045
03400062
03400078
50
03400100
04400150
34
04400172
05400270
31.5
05400300
18
06400350
06400420
17
06400470
07400660
9.0
07400770
07401000
7.0
08401340
08401570
Unidrive M702 User Guide
Issue Number: 3
Electrical
Getting
Basic
installation
started
parameters
the motor
Instantaneous
Continuous
power rating
power rating
kW
kW
1.5
1.9
8.5
2.8
3.6
4.6
9.4
6.3
10.3
8.6
12.6
19.7
16.4
20.5
27.8
24.4
37.6
32.5
Instantaneous
Continuous
power rating
power rating
kW
kW
1.5
2.0
9.2
2.8
4.6
5.0
13.6
6.6
9.0
19.9
12.6
21.5
16.2
37.5
19.6
21.6
39.8
25
32.7
41.6
75.2
50.6
96.6
60.1
Running
NV Media Card
Optimization
Operation
Table 4-21 Braking resistor resistance and power rating (575 V)
resistance *
Model
05500030
05500040
05500069
06500100
06500150
06500190
06500230
06500290
06500350
07500440
07500550
08500630
08500860
Table 4-22 Braking resistor resistance and power rating (690 V)*
resistance *
Model
07600190
07600240
07600290
07600380
07600440
07600540
08600630
08600860
* Resistor tolerance: ±10 %
For high-inertia loads or under continuous braking, the continuous power
dissipated in the braking resistor may be as high as the power rating of
the drive. The total energy dissipated in the braking resistor is dependent
on the amount of energy to be extracted from the load.
The instantaneous power rating refers to the short-term maximum power
dissipated during the on intervals of the pulse width modulated braking
control cycle. The braking resistor must be able to withstand this
dissipation for short intervals (milliseconds). Higher resistance values
require proportionately lower instantaneous power ratings.
In most applications, braking occurs only occasionally. This allows the
continuous power rating of the braking resistor to be much lower than
the power rating of the drive. It is therefore essential that the
instantaneous power rating and energy rating of the braking resistor are
sufficient for the most extreme braking duty that is likely to be
encountered.
Optimization of the braking resistor requires careful consideration of the
braking duty.
Select a value of resistance for the braking resistor that is not less than
the specified minimum resistance. Larger resistance values may give a
cost saving, as well as a safety benefit in the event of a fault in the
braking system. Braking capability will then be reduced, which could
cause the drive to trip during braking if the value chosen is too large.
Thermal protection circuit for the braking resistor
The thermal protection circuit must disconnect the AC supply from the
drive if the resistor becomes overloaded due to a fault. Figure 4-18
shows a typical circuit arrangement.
Onboard
Advanced
Technical
PLC
parameters
data
Minimum
Instantaneous
power rating
Ω
kW
80
12.1
13
74
Minimum
Instantaneous
power rating
Ω
kW
UL listing
Diagnostics
information
Continuous
power rating
kW
2.6
4.6
6.5
8.7
12.3
16.3
19.9
24.2
31.7
Continuous
power rating
kW
67
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