What are variable frequency drives?

VFD (Variable Frequency Drives) are special systems for regulating an AC motor's torque and speed of rotation. The devices use frequency and voltage regulation to adjust the motor’s operation. They are also known as variable speed drives, inverter drives, or simply called drives.

The voltage conversion takes place in three stages:

• From Diodes to Capacitors (converting from AC to DC)
• Form Capacitor to Transistor (cleaning DC)
• From Transistor to Motor (converting from DC to AC)

This multistage voltage processing contributes to the most efficient and safe motor operation. Due to frequency changes the motor`s shaft rpms changes too. In this way, we can anytime flexibly adjust motor speed, using a VFD. Using drives increases efficiency (the motor gets exactly as much as it needs) and safety (it is possible to start and stop smoothly). The work of a frequency converter can be controlled by a PLC (programmable logic controller).

Siemens variable frequency converters

Siemens has been manufacturing variable frequency drives for decades and has created hundreds of different types and series. In all this variety, it is easy to get confused.

There are four main types of Siemens VFD:

• Low voltage
• Medium voltage
• Servo drives
• DC converters

Each of the presented groups is created for a certain purpose. Low voltage drives group is the most basic and popular. Let`s clarify it in detail. You also can see all described variable frequency converters in this Siemens drives catalog.

Siemens Low Voltage Drives

Devices in this group are often used for simple general-purpose tasks. Their voltage range is from 0.12 kW up to 6840 kW.

There are four subgroups of Siemens low voltage converters:

• Standard Performance (0.12kW to 2700kW)
• High Performance (0.55 kW to 2500 kW)
• Servo Drives (0.1 kW to 6840 kW)
• Special Types (for pumps, fans, conveyors)

The standard Performance type is quite universal for common industrial tasks. It will be perfect for simple applications. Such converters can be used almost everywhere, but not for complex tasks. Their main feature is high performance at a low price.

This Product Line includes SINAMICS V20, G120C, G120, G130, G150.

High-performance drives are the next level of standard ones. They offer high-performance speed control and compact modular design. Such devices are made for machinery, machine building, and plan engineering. Their main features are high performance and accuracy.

This Product Line includes SINAMICS S120 and S150 Series.

Servo Drives is a pair of Servomotor and frequency converter. A well-functioning servo system provides faster feedback. Such systems are most commonly used in machine tools, mobile machinery, and other motors. This will be a good solution for situations where a robust drive is needed to perform basic tasks. The main advantages of this group are durability, reliability, and fast response.

This Product Line includes SIMATIC Micro-Drive, SINAMICS V70, V90, and S120.

Special types

Special types are designed for work with specific types of industrial equipment. Therefore, the efficiency of their work is significantly increased at the same cost. On the other hand, they are only effective with this specific industrial equipment.

The company creates a special series for work in conveyor systems: SINAMICS G115D, G110D, G110M, G120D, and SIMATIC ET 200pro FC-2.

There are also special series for usage with pumps, fans, and compressors: SINAMICS G120X, G120P, and G180.

The main advantages of the presented group are stability, resistance to harsh conditions, and dozens of frame sizes by choice.

How to replace the Micromaster series?

The MICROMASTER drive family is already outdated. As this product line has reached its ceiling with a technological upgrade, all micro-master actuators replaced by the new SINAMICS drives family. 

The Siemens MICROMASTER converter type had three main series:

• MICROMASTER 420
• MICROMASTER 430
• MICROMASTER 440

Let's determine which series we can replace your obsolete inverters with.

Micromaster 420 was replaced by the G120 and G120 C series.

Mircomaster 430 was replaced by the G120X series.

Micromaster 440 was replaced by also G120 and G120 C series.

All new models are adapted to replace outdated devices. These are all actual groups of low-voltage frequency converters at the end of 2020.

If you are looking for a reliable Siemens Drives distributor, feel free to contact Eltra Trade Company.