A large number of variable-speed drives in a wide power and speed range are used in process plants and systems. When it comes to erecting and operating plants and systems, things are a lot more straightforward if all of the drives can be engineered, commissioned, optimised and maintained using one and the same system. An integrated engineering system supports users as soon as it allows the most favourably priced drive to be selected for each particular drive task.
Volker Böhm, Roland Knippert
Siemens took on the challenge quite some time back to provide integrated and seamless engineering extending beyond the borders of individual product families – and implemented this in the form of Totally Integrated Automation. In addition to functional integration, the appropriate software tools were created on a standard platform – independent of the drive type. These are the Sizer program for engineering and the Starter program for commissioning variable-speed drive systems. An integrated engineering system with a standard, unified philosophy was thereby established. Drives from different product families can be selected, sized, commissioned, optimised and maintained with the help of integrated, seamless operator interfaces and databases. Micromaster 440 and Sinamics drive units in the chemical industry version are especially ideal for use in the chemical process industry.
These drive systems, fully embedded in the engineering tool environment, cover a power range from 0.12 to 800 kW. The circuit technology corresponds to PELV criteria. Connecting panels in compliance with Namur Recommendations NE37 and NE38 are also available. The Atex 100a Directive is fulfilled in combination with explosion-protected motors which can be directly engineered and parameterized in Sizer and Starter.
From 120 W to 800 kW with just one system
Although Siemens Micromaster 440 and Sinamics G150 inverters have different prod-uct names, together they cover the range of power ratings required in plant construction. Micromaster 440 inverters are used up to 90 kW. Depending on the particular drive application, they can be parameterized for constant or variable load torque characteristics. In addition to improving usability, one of the objectives was also to minimise the space required by the drive. The commutating reactors and LC output filters for the Micromaster drive units are designed as sub-chassis components up to a power rating of 15 kW. Micromaster 440 is intended for installation in electrical cabinets.
The Sinamics G150 cabinet units, that from a total engineering perspective are compatible with Micromaster 440, extend the power range of variable-speed drive solutions up to 800 kW. The mechanical design of the G150 has been optimised to address fan, pump and compressor applications in industrial environments. It offers – as standard – sensorless vector control for fans and pumps with square-law load torques.
Its electrical cabinet is especially compact. Compared to conventional inverters with the same power rating, the G150 has a 50 % smaller footprint. If the inverters are connected up centrally and the corresponding components do not have to be accommodated in the electrical cabinet, then the footprint is reduced by as much as 70 %. Electrical cabinet versions are available with degrees of protection up to IP 54, which certainly increases the degree of flexibility if the drives need to be installed in the field – and it also helps to keep motor feeder cables short. The drive technology of the G150 is additionally available as a modular chassis unit under the name Sinamics G130.
Both of these drive families allow frequency bands to be suppressed in order to avoid mechanical resonance effects. This function can also be used to prevent uncontrolled high pressure levels in the medium being transported or pumped as a result of standing waves. Automatic restart after power failure, bumpless connection to a motor that is already spinning and parameterizable ramp-up and ramp-down times with rounding-off reduce the stress on the mechanical system – and play an important role in achieving a long lifetime and maximum operational readiness for the complete plant or system. An extensive range of motor monitoring functions fulfils the strict safety requirements of the process industry.
Integrated motor protection
The IGBT technology, utilised in both of the inverter families, ensures extremely efficient operation. Furthermore, this technology allows electronic measures to be implemented to achieve a high degree of protection against voltage spikes and critical voltage rates-of-rise at the output.
Equipped with LC or sinusoidal filters, the inverters are able to feed motors that are located up to 300 m away in hazardous areas. Not only this, but these filters allow the plant construction company to use older types of induction motor or motors from other manufacturers thanks to the smoothed, sinusoidal voltage characteristic.
Seamless connection at the control and IT levels
All of the Micromaster 440 and Sinamics G150 low-voltage inverters use the Profibus fieldbus to communicate with the plant control system. This communications link allows the inverter parameters to be directly accessed. The drive can be configured, the settings checked and the status data interrogated from a central location without having to go anywhere near the drive. This is especially helpful when commissioning drives that are distributed across considerable distances. The DriveES Basic software component on the one hand allows the drives to be integrated into the Simatic environment and on the other hand facilitates remote access – if necessary, extending beyond network limits. This is an essential prerequisite when it comes to offering remote maintenance of the plant or system via a WAN or the telephone network – right down to the finest detail of the drive parameters and motor data.
The number of interfaces and protocols within the plant automation concept is drastically reduced owing to the integrated system philosophy encompassing all of the products. Compared to using several stand-alone drive solutions, this directly reduces the time and costs for designing, implementing and maintaining the automation environment. Not only this, but process safety increases as communication complexity is reduced.
The drafted Namur recommendation to enable Profidrive profile 3.1 to be used in the process industry independently of the manufacturer pursues a similar objective. Siemens is a member of this working group and has already included the necessary software structures in its latest inverters. As soon as the Namur recommendations for non-proprietary use of Profile 3.1 have been finalised, all that will be required is a firmware update for the cabinet units to allow these inverters to be opened for the new standard.
Micromaster 440 and Sinamics G150 also prove their communications capability in the field, directly at the drive unit. Both of these device families offer rugged operator panels with plain text menus and the IP 54 degree of protection for local monitoring, operator control and maintenance. The sophisticated multi-level safety concept means that unauthorised personnel cannot tamper with the drive unit settings. The drives can optionally be used without a higher-level control.
Reduced costs and increased process safety
Siemens has efficiently combined its variable-speed drive solutions for the chemical and pharmaceutical sectors and made them available in a unified, integrated and seamless engineering environment. This represents an important step towards providing complete solutions from a single source, which is the preferred business model in the process industry. In contrast with the usual single-vendor portfolios, if several product families are embedded in a common engineering system, this has the advantage that drive solutions optimised from a cost perspective can be offered where otherwise standardised and oversized units would be given preference for the sake of simplicity.
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