SIEMENS
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Siemens IC 10 · 2017
Solid-State Switching Devices for Switching Motors
Solid-State Contactors
General data
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Overview
Solid-state contactors for switching motors
Solid-state contactor for direct-on-line starting
The solid-state contactors for switching motors are intended for
frequently switching on and off AC drives up to 7.5 kW and
reversing up to 3.0 kW. The devices are constructed with
complete insulation and can be mounted directly on SIRIUS
motor starter protectors, overload relays and current monitoring
relays, resulting in a very simple integration into motor feeders.
These three-phase solid-state contactors are equipped with a
two-phase control which is particularly suitable for typical motor
current circuits without connecting to the neutral conductor.
Important features:
• Insulated enclosure with integrated heat sink
• Degree of protection IP20
• Integrated mounting foot to snap on a standard mounting rail
or for assembly onto a support plate
• Variety of connection methods
• Plug-in control connection
• Display via LEDs
• Wide voltage range for AC control supply voltage
Switching functions
The solid-state contactors for switching motors are
"Instantaneous switching
", because this method is particularly
suited for inductive loads. By distributing the ON point over the
entire sine curve of the mains voltage, disturbances are reduced
to a minimum.
Connection methods
You can choose between the following connection methods for
the solid-state contactors for switching motors:
Screw connection
The screw connection system is the standard among industrial
controls. Open terminals and a plus-minus screw are just two
features of this technology. Two conductors of up to 6 mm² can
be connected in just one terminal.
Spring-type connection
This innovative technology manages without any screw
connection. This means that very high vibration resistance is
achieved. Two conductors of up to 2.5 mm² can be connected
to each terminal.
Motor feeders
The devices can use a link module to directly connect to a motor
starter protector. Also possible is the mounting of a
3RB30/3RB31 electronic overload relay
(see page 7/90)
or a
3RR2 current monitoring relay
(see pages 10/62 and 10/70)
using a link adapter. The simultaneous mounting of a motor
starter protector and an overload or current monitoring relay is
not recommend for space and heat development reasons.
Rapid-switching fuseless and fuse motor feeders can thereby be
implemented in a time-saving manner.
Selecting solid-state contactors
The solid-state contactors are selected on the basis of details of
the network, the load and the ambient conditions.
The following procedure is recommended:
•Determine the rated current of the load and the mains voltage
•Select a solid-state contactor with the same or higher rated
current than the load
•Testing of the maximum permissible switching frequency
based on the characteristic curves
(see "More Information"
➞
"Product Information")
. To do this, the starting current, the
starting time and the motor loaded in in the operating phase
must be known.
•If the permissible switching frequency is under the desired
frequency, it is possible to achieve an increase only by
overdimensioning the motor and the solid-state contactor!
Alternatively, the tool for "Selection of solid-state contactors for
switching motors" can be used. The correct device size can be
determined by entering the network and motor data along with
the application and ambient conditions,
see
www.siemens.com/solid-state-switching-devices.
Short-circuit protection
Despite the rugged power semiconductors that are used, solid-
state switching devices respond more sensitively to short
circuits in the load feeder. Consequently, special precautions
have to be taken against destruction, depending on the type of
design.
Siemens generally recommends using SITOR semiconductor
fuses. These fuses also provide protection against destruction in
the event of a short circuit even when the solid-state contactors
and solid-state relays are fully utilized.
Alternatively, if there is lower loading, protection can also be
provided by standard fuses or miniature circuit breakers. This
protection is achieved by overdimensioning the solid-state
switching devices accordingly.
More information
For additional information,
see the system manual
"SIRIUS Innovations - System Overview" and the manual
"SIRIUS Innovations - 3RF34 Solid-State Switching Devices":
.
Product information and technical specifications
For product data sheets with detailed technical specifications,
dimensional drawings and characteristic curves
see
.
For additional information, please enter the article number of the
required device under the tab "Product List".
© Siemens AG 2016