User’s Manual
73
7.1.2.
C
OMMON
B
US
A
PPLICATION
N
OTE
Bonitron heavy duty braking transistors are designed to be compatible with
individual stand-alone inverter/drive systems, or systems that incorporate a
common DC bus arrangement. The common DC bus can be composed of
multiple inverter/drive sections tied together where all or some of the sections
use their respective AC input, or there may be a large independent Master
DC bus supply feeding the DC inputs of all inverter/ drive sections. In the
case of the large Master DC bus supply, it is common to find multiple rectifier
sections in parallel to provide very high power levels. Some high power
systems also include redundant or back up sections as well.
Once power is applied, all Bonitron modules are designed to be sourced from
DC buses that have all the bus capacitors present.
Common DC bus systems composed of separate Master DC bus or rectifier
sections have important imbedded differences. It is common to have a main
distributed DC bus, and this is typically where the heavy duty braking
transistors connect. In this way, the dynamic braking system is always
present, even if some of the inverter/drive sections need to be removed from
the bus for maintenance or other purposes. In emergency situations, it may
even be necessary to “limp” along until repairs or swap outs can occur. Even
though the modules are well suited for use in these systems, the following
modes of operation could arise or exist and
are not allowed
:
1.
Do not
connect the heavy duty braking transistor on the rectifier side of
a DC link choke. The connections must always be made to the
inverter/drive side directly to the DC bus capacitors. During normal
system operation, the choke can cause the braking system to begin
ringing. This ringing causes high voltages that will damage the system.
2.
Do not
energize the system with no inverters/drives present on the
distributed DC Bus.
3.
Do not
energize, operate, or run the system with less than 60% of the
total expected system capacitance present.
4. Operating the modules in conditions 2 and 3 may make the modules
respond to inbound line transients caused by SCR type rectifiers,
powering up the system, or any number of other sources. Without
sufficient DC bus capacitance, the DC bus will not be filtered, and can
cause ringing that will produce high voltages that will damage the system.
5. In some drives, the pre-charge contactor may open under fault
conditions, leaving the bulk system capacitance only resistively coupled
to the heavy duty braking transistors.
Do not
enable the modules in this
situation. Review inverter/drive DC bus pre-charge circuit operation with
the drive manufacturer.
If there is the possibility of these situations:
•
Open the enable input on the R7 or R7E options.
•
Use
a properly rated contactor in series with the modules’ control voltage
AC Input. The modules are effectively disabled when they do not have
their control power.
•
Keep the modules disabled during power up or any other time until all
system capacitances are present.
•
Disable the modules in the event system pre-charge contactors open.
Summary of Contents for M3452
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Page 19: ...User s Manual 19 Figure 3 2 Customer Connections in K9 Chassis CUSTOMER I 0 CONNECTION ...
Page 21: ...User s Manual 21 Figure 3 2 Customer Connections in M14 Chassis CUSTOMER I O CONNECTION ...
Page 24: ...M3452 vR7 EIP PDP 24 Figure 3 6 I O Hookup with R7 EIP PDP Communication ...
Page 26: ...M3452 vR7 EIP PDP 26 Figure 3 8 24VDC Power Connection ...
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Page 66: ...M3452 vR7 EIP PDP 66 Figure 6 3 M3452 K9 Chassis Dimensional Outline Drawing ...
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Page 75: ...User s Manual 75 NOTES ...
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