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From top to bottom, Siemens revamps its Sirius Modular System

Author : Michael Babb

29 November 2009

With the improved low voltage controls, users are able to monitor not only the motor itself but the entire application. Developments in both the main circuit and control circuits add more functions in the basic units, which have been designed to facilitate control cabinet construction and reduce wiring costs. The components can be connected into the automation level via AS-Interface and IO-Link.

The Sirius Modular System of low voltage control components
The Sirius Modular System of low voltage control components

Eckard Eberle, Head of the Control Components Business Segment Siemens AG, announced at the SPS/IPC/Drives show that his company has made extensive improvements throughout its Sirius Modular System. The low voltage control products are now available for switching, starting, protecting and monitoring plants and motors, with smaller designs that increase efficiency in control cabinet construction.

With the same size, for example, the components of the Sirius Modular System now cover a larger performance range: up to 7.5 kilowatts in size S00, and up to 18.5 kW in size S0 at 400 volts.

The 3RT2 Contactors can be used in a current range up to 38 A, and the 3RV2 circuit breakers up to 40 A; both with an installation width of just 45 millimetres.

Part of the new Sirius Modular System—the 3RW30 and 3RW40 Soft Starters as well as the 3RA6 Compact Starter—was already launched in the market last year.

New for direct starting
To construct direct starters, reversing starters or star-delta starters, users no longer have to get involved with costly wiring. Instead can plug the Sirius 3RA27 and 3RA28 Function Modules into Sirius 3RT2 contactors; and so avoid installation errors.

On-delay or off-delay time relays are already integrated into the module for constructing a direct starter.

The function module for the star-delta starter contains the control logic and the time setting. The modules are suitable for both contactor sizes S0 and S00. They are also suitable for the most varied coil versions thanks to their wide-voltage electronics, allowing them to be used flexibly for all motors.

The contactors themselves have also been expanded in their functionality, for example through already installed auxiliary switches or UC coil versions.

The components are supplied with power via the Sirius 3RV29 or 3RA6 Infeed System. For this, the individual circuit breakers, complete load feeders or compact starters are simply clicked into the infeed systems.

All components of the modular system are equipped alternatively with screw-type connections, spring-loaded connections or ring cable lugs. The gas-tight terminal connection of the spring-loaded system is resistant to bumps and vibration.

The components in the spring-loaded version have an additional plug-in connection interface enabling the construction of direct starters, reversing starters or star-delta starters without tools.

Communication-enabled function modules that are clicked onto the Sirius 3RT2 contactors connect the load feeder with the controller via AS-Interface or IO-Link. Bundling of these signals dispenses with the need for parallel wiring to the controller.

Since the Sirius devices are integrated into the Step 7 engineering system of the Simatic S7 controllers, all the load feeder data are available centrally in the controller and can be conveniently transferred and evaluated. These data include, for example, the control and status signals of the load feeders such as "Ready," "On/off," or "General warning/fault."

Eckard Eberle, Head of the Control Components Business Segment Siemens AG
Eckard Eberle, Head of the Control Components Business Segment Siemens AG

Previously unavailable diagnostics messages like "Mode," "End position left/right" or "Device defect" can be pre-processed via IO-Link without the usual configuring overhead. In this way, faults are located immediately and made available in plain text at a central location or via HMI (human machine interface) displays on-site, so they can thus be quickly rectified.

Monitoring the application
Direct integration of 2- and 3-phase monitoring relays into the load feeder means that not only the motor but also the application can be monitored.

The 3RR2 Monitoring Relay for current monitoring is mounted directly on the contactor. As well as the motor and the process it drives, it also monitors the connected plant sections for overcurrent, undercurrent, wire break or phase failure.

This enables quick detection and reporting of load shedding or machine overload, for example, and increases plant availability. The analogue version of the monitoring relay is parameterised using rotary switches, and the digital version using buttons and a display with menu-prompting. The digital version also enables fault current monitoring and phase-sequence monitoring.

Less work for panel builders
“For machine builders and, in particular, control cabinet assemblers, Sirius means less effort with configuration, assembly and testing,” said Mr. Eberle at a press conference organised at SPS/IPC/Drives to launch the new products.

“More performance without increasing the design width saves space in the control panel. Moreover, fewer parts are required because the components feature a wide range of integrated functions,” he said.

“In terms of efficiency in the control cabinet, reducing the power dissipation up to ten percent also has a major impact. Innovative contact materials reduce the contact resistance in the main circuit. Waste heat developing inside the control cabinet is reduced by the new electronic control inside the contactor coils, optimised bimetal strips in the protective devices or alternatively by means of electronic current sensing. Thanks to the increased power density, minor switching devices are able to take on tasks which previously required larger ones. This brings down the size of the control cabinet, allowing both air conditioning systems and power supplies to be designed on a smaller scale.

“The adverse effect of dirt and dust can be reduced by the use of high-quality materials and ‘ribbed’ contact surfaces on auxiliary contacts make for greater increase in contact reliability.

“Loose terminals caused by vibrations and shocks are minimised since all components in the enhanced Sirius Modular System are offered with spring-loaded terminals in both the main circuit and the control circuit.

“Our new current monitoring relays enable users to monitor the entire application, beyond the motor,” he said.
The main innovations at a glance:
* All components in the main circuit up to 40 amps (A) / 38 A have an overall width of 45 mm;
* 3RR2 Monitoring Relay for current monitoring with direct connection to contactors;
* 3RU2/3RB3 Overload Relay, available in a thermal or electronic version;
* 3RA28 Function Modules for easier mounting of direct starters, reversers and star-delta starters;
* 3RA27 Function Modules for connecting entire feeders to the PLC, either via AS interface or IO link;
* 3RA2 Load Feeders for top-hat (DIN) rail and bus-bar mounting;
* 3RA6 Compact Feeders with optional interface to AS interface and IO link;
* 3RW30 / 3RW40 Soft Starter to reduce the starting torque and power peaks;
* 3RF34 solid-state switches for noiseless switching and extreme switching frequencies; and
* As well as optimised details such as consistent connection systems in screw terminals, spring-loaded connection systems and ring tongue terminals; the patented plug-in technology for combining devices without the need for tools.

Four areas of benefits
Mr. Eberle said he had categorised customer benefits into four groups: Assembly and Handling, Planning and Configuration, Application Monitoring and Connection to the PLC.

“First of all, one of the highlights of the Sirius Modular System is the reduced assembly and handling work involved,” he said.

“Another benefit in this field is the termination method.

“For the first time, a consistent spring-loaded connection system is available for the full range. Spring-loaded modular system components are particularly useful in mechanically complex applications, but they now provide an additional benefit: An additional connector interface enables tool-free combination of direct starters, reversers, or star-delta starters.

“Moreover, all components are also available with screw terminals and ring tongue terminals to meet special requirements

The "four advantages" strategy
The "four advantages" strategy

“Assembling a direct starter, a reverser or a star-delta starter no longer requires extensive wiring.

“The Sirius Function Modules are simply plugged into the Sirius Contactors in order to avoid mounting errors. The module used for assembling a direct online starter is equipped with integrated ON and OFF delay timing relays.

“The function module used for assembling a star-delta starter contains the control logic and time setting and thus replaces the auxiliary switches, the time relay and the control circuit wiring which are otherwise additionally needed.

“Individual circuit breakers and entire feeders are simply clicked into the feeder system, without the need for tools or complicated wiring, thus avoiding any risk of errors.

“Thanks to the wider performance range covered by the S00/S0 design sizes and the extended functions provided by the individual components of the modular system, the number of variants and parts involved is greatly reduced, as is the work required for assembly and order placement. The new 3RT2 Sirius Contactors, for example, now come with the auxiliary switch fully integrated.

Improved application monitoring
Mr. Eberle was particularly excited about the possibilities in application monitoring.

“In the future, our new current monitoring relays will enable users to monitor not just the motor but the entire application—and this is done directly from the load feeder,” he said.

“Two and three-phase monitoring relays are directly integrated into the load and monitor both the motor, the driven process and all connected parts of the system for overcurrent and undercurrent, cable breakage and phase failure.

“In this way, for example, load shedding or motor overload are detected and signalled early on in the process. The PLC responds to the specific event and duly shuts down the system before a motor circuit breaker cuts off the entire feeder.

“Parameterisation of the monitoring relays is done via rotary switch in the analogue version and in the digital version using keys and a display with menu-guided setting. The digital version additionally supports fault current and phase sequence monitoring.

Link to the PLC
Since communication with the PLC plays such a major role in plant availability, the . load feeders are made so that they easily and rapidly connect to the PLC via Sirius function modules. Communication is via AS interface and IO link.

With the Step 7 engineering system, all load feeder data are centrally available in the PLC and can be conveniently transmitted and evaluated. Control and status signals of the load feeders such as readiness indication, ON/OFF, or group warning/fault are available in the same structure irrespective of the type of starter they are sent from.

Diagnostic messages such as operating mode, limit position right/left, or device defect, which were previously unavailable, can now be directly processed via IO Link without the previously required configuration work.

This allows faults to be immediately located and displayed in plain text centrally or via on-site HMI (Human Machine Interface) displays, for rapid troubleshooting. In this way, both entire systems and parts of the system can be centrally diagnosed, monitored, and maintained.

Further information at: www.siemens.com/sirius-innovations

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