Specifications
AS-Interface slaves
Motor starters for operation in the field, high degree of protection
SIRIUS MCU motor starters
General data
6/107
Siemens IK PI · 2012
6
■
Overview
Portfolio of the SIRIUS 3RK43 MCU motor starter family
The SIRIUS MCU motor starter family (MCU = Motor Control
Unit) rounds off the bottom end of the SIRIUS motor starter
range.
This series of motor starters in a high degree of protection is a
system solution for the cabinet-free controlling of AC loads in the
field.
The MCU product range extends from I/O-controlled motor
starters – addressing a central sub-distribution board via I/O sta-
tions – in a plastic enclosure for simple applications to motor
starters with AS-i communication in a rugged metal enclosure for
demanding tasks. (For full range, see Catalog IC 10 --> Motor
starters for operation in the field, high degree of protection)
The MCU motor starters are completely pre-wired inside, have a
high degree of protection and are designed for switching and
protecting any AC loads. They are mostly used on standard in-
duction motors in direct or reversing duty up to 5.5 kW at
400/500 V AC (electromechanical switching) and 400/460 V AC
(electronic switching).
The motor and short-circuit protection integrated in the MCUs
consists either of an electromechanical controlgear assembly or
solid-state overload protection and a motor starter protector unit
for short-circuit protection.
MCUs with metal enclosure are designed for the switching of in-
duction motors. Integrated control of the electrically operated
motor brake with a braking voltage of
230 V AC or 400 V AC is a
standard feature. The
braking voltage is routed to the motor over
the motor cable.
SIRIUS MCU motor starters have the following main features:
• Direct-on-line or reversing starters
• Up to 5.5 kW
• High degree of protection, namely IP55 on MCU motor starters
in a plastic enclosure and IP54 on motor starters in a metal
enclosure, enables distributed configurations in the field and
saves space in the control cabinet
• Electromechanical or electronic switching
• Easy and user-friendly control and monitoring through
AS-Interface bus communication
• Controlled stopping through brake control 230 V AC or
400 V AC for motor brake
• Integrated lockable repair switch
• Comprehensive motor protection thanks to integrated over-
load and short-circuit protection with SIRIUS 3RV motor starter
protectors or integrated solid-state overload relays (solid-state
starters)
• Overload protection with thermal release (bimetal) or
solid-state overload relay with wide range setting
• Power and load connection by means of an M screw
• Main power loop possible (daisy chain; max. 2 x 6 mm
2
)
• Robust and widely used M12 connection method for digital in-
puts and outputs to connect I/O stations and the AS-i bus con-
nection increase flexibility and prevent errors in the system
configuration.
• The LEDs (for AS-i bus connection) can provide comprehen-
sive diagnostics of the device on the spot.
• Simple mounting for AS-i and external auxiliary voltage
(24 V DC) over an M12 connection
• Manual operation: An integrated key-operated switch
"MAN-0-AUTO" and a selector button for switching on, switch-
ing off and changing the direction of rotation for control pur-
poses during commissioning or maintenance
MCU motor starters with AS-i bus connection
in a plastic enclosure
This motor starter version offers an economical solution for con-
trolling and monitoring conveyor belts, pumps, fans or compres-
sors.
On this MCU the control commands and the status queries are
sent over the AS-i bus. The yellow cable (bus) and the black
AS-i cable for 24 V DC AUX are connected through a M12 plug.
The transparent enclosure top permits monitoring of the status
LEDs. These MCUs come completely pre-wired inside.
MCU motor starters with AS-i bus connection in a metal
enclosure for electromechanical or electronic switching
These MCUs with their rugged metal enclosure in degree of pro-
tection IP54 are ideal in particular for controlling and monitoring
induction motors in harsh ambient conditions such as are often
found in conveyor systems.
A special feature of this version is the manual local operation of
the motor starter.
The key-operated switch "MAN-0-AUTO" for selecting Manual,
0 or Automatic mode prevents unauthorized changes of operat-
ing mode. In automatic mode the MCU is controlled through the
AS-i bus.
In manual mode a selector button is used for switching on,
switching off and changing the direction of rotation.
The status/diagnostics LEDs fitted to the cover indicate the
current operating state of the motor starter.
Unlike the electromechanical starter, the solid-state motor starter
has wear-free solid-state switching devices which guarantee a
high switching frequency.
Another highlight of the electronic switching version is the
solid-state overload relay for motor protection, which has a wide
setting range for the motor current.
3RK43 20-3.R51-.BA0
3RK43 20-3.Q54-.BA.
3RK43 20-5.Q64-.BA.
Kap_06_en.book Seite 107 Freitag, 2. September 2011 1:42 13
© Siemens AG 2011