Contactors for Switching Motors
The solid-state contactors for switching motors are intended for frequently switching on and off three-phase current operating mechanisms 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.
Overview
Solid-state contactors for switching motors
The solid-state contactors for switching motors are intended for frequently switching on and off three-phase current operating mechanisms 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 for snapping onto a standard mounting rail or for mounting on 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 terminal
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-loaded terminal
This innovative technology manages without any screw terminal. 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 or a 3RR2 current monitoring relay using a link adapter. The simultaneous mounting of a circuit breaker and an overload or current monitoring relay is not recommended due to space and temperature rises.
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!
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 utilised.
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.
Online Configurator
- Simple selection of individual solid-state switching devices by means of technical characteristics (e.g. zero-point switching, spring-loaded terminal and rated current)
- Once configuration is complete, you receive the article numbers corresponding to the products.
Build innovative machines faster without costly prototyping with Efficient Motion Control.
With Effective Motion Control, machine builders can easily overcome major challenges and enable faster time-to-market, increased functionality, resolve complex system requirements, and demands for safety and sustainability.
We are Siemens trusted and approved distribution partner.
As a Value Added Reseller in Siemens’ Approved Partner network, Parmley Graham are a proven supplier of a wide range of quality products in the UK and globally.
Find out more how this will benefit you or check Siemens Configurator.
