Eaton Industrial Switchgear - xStart switching, protections and actuating motors

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2010 CA08103002Z-EN
Frequency inverters
Braking resistors
10/13
Braking resistorsDescription
I
OK
BACK
RESET LOC
REM
R-
MMX
BR2
R+
I
OK
BACK
RESET LOC
REM
BR…-T-SAF braking resistor in subassembly frame
Type overview
Application
An external braking resistor is
required for braking larger moments of
inertia or for prolonged regenerative
operation. This converts the motor’s
mechanical braking energy into heat.
Features
These resistors are built into a perfo-
rated metal sheet enclosure and
equipped with a thermostatic circuit-
breaker (230 V, 1 A, AC-1). The enclo-
sures are made of galvanized sheet
metal and are open at the bottom. They
fulfil protection type IP65 only in their
fitted state.
With a combination of several series-
and parallel-connected resistors,
a higher braking power can be
achieved. The braking resistors can
be connected directly to the brake
choppers of MMX34… frequency
inverters.
Function
The frequency inverter’s built-in
braking transistor automatically
switches in the connected braking
resistor as soon as the internal DC link
voltage exceeds the switching thresh-
old. This prevents excessive voltages
on the internal DC link, which would
otherwise cause an overvoltage fault
message and the frequency inverter’s
pulse inhibitor to be set. The drive then
coasts to a halt uncontrolled.
Documentation
The documentation can also be
obtained on the Internet from:
BR1...-T-PF, BR3...-T-PF
Braking resistors
2 T1
T2
1
i
PE
RB
Type overview
Features
BR2… is a short-circuit proof,
intrinsically safe braking resistor in
an anodized aluminum enclosure with
protection type IP65 and without a
thermostat.
Note: When used according to UL
directives, the rating data for
continuous braking and the maximum
pulse performance must be reduced
by 25%.
Caution: The surface temperature can
exceed 100 °C!
• BR2...-T-SAF is a combination of
several braking resistors BR2…
braking resistors with a thermostat.
They are built into a subassembly
frame for the
M-Max™ frequency inverters.
• BR1...-T-PF is a braking resistor or
a combination of several braking
resistors with a thermostat. It is
installed in an encapsulated
enclosure with protection type IP54
and protected against accidental
contact.
• BR3...-T-PF is a braking resistor
in a steel mesh design with a
thermostat. It is installed in an
encapsulated enclosure with
protection type IP54 and protected
against accidental contact.
• ...- T = with a thermostat
• ...- SAF = subassembly frame
• ...- PF = protection frame (protects
against accidental contact)
BR2..., BR2...-T-SAF
Braking resistors
BR...