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Distributed inverters draw 20% less current

13 April, 2007

Siemens has developed an IP65-protected inverter for distributed applications such as conveyor drives which, it claims, draws about 20% less current than rival drives. The low-profile Sinamics G120D inverter (shown below) is available in ratings from 0.75–7.5kW, and has built-in safety functions.

Siemens distributed inverter

The lower current requirement, and a corresponding reduction in reactive power, is the result of an "innovative power-infeed concept". This allows installations to be designed to operate at lower power levels than normal, and avoids the need for line-commutating reactors, brake choppers and brake resistors. It is also said to allow the inverter to feed energy back into the power supply during braking with much less harmonic distortion than standard frequency inverters.

The "unique" safety functions built into the inverters include "safety torque off", safe stop and "safely limited speed". These functions do not need an encoder input, and are activated and de-activated using the Profisafe protocol.

The flat shape of the inverters means that they can be mounted in narrow spaces. All versiosn share the same footprint, making it easy to upgrade or downgrade an installation, if needed. A modular design allows the power section to be replaced without disconnecting the wiring or fieldbus connections. Data is stored on micro memory cards, allowing the drives to be replaced or cloned rapidly.