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Choosing the right cables and inverters


Choosing the right cables and inverters

Knowledge of the working mechanism of inverters, their basic features and parameters can significantly facilitate the process of choosing the right device. The stability of the system depends on the device and its dedicated cabling.


What are the inverters and their uses?

Inverters are often referred to as power supply controllers for [electric motors]COUNTRY}/{LANG}/katalog/silniki-elektryczne_100611/) due to their ability to adjust the voltage frequency, which results in regulating the rotation speed. As we all know, frequent changes of the supply voltage have negative influence on the operation of a motor – lower voltage means fewer revolutions. That is why the possibility of effective frequency and voltage control turns out to be a vital advantage of using inverters.

Choosing the right cables and inverters

Types of inverters

Inverters can be divided according to the type of power supply or the control method used in the device. Therefore, we can differentiate between:

  • single-phase inverters with 230V phase-to-phase output voltage resulting from the method of powering this type of devices, i.e. single-phase 230V.

  • three-phase inverters with 230-500V phase-to-phase output voltage. It is related to the device’s three-phase power supply with voltage ranging from 230 to 500V.

  • scalar inverters, whose name derives from type of implemented scalar control. It may have a linear characteristic with a constant ratio of output voltage and output frequency (u/f = const.); or a square characteristic (U/f²=const.) with an increase in frequency causing increase in voltage per square.

  • Vector inverters, which often utilize advanced control algorithms. We differentiate between two types of vector control: field-oriented control and direct torque control. Like all electrical devices, inverters are characterized by parameters allowing for their classification. The most important parameters include:

  • the maximum motor power that allocates the inverter to a specific motor with a power that cannot be exceeded. The power cord is also selected on its basis. Only a properly assembled set will ensure long and reliable operation of the devices.

  • supply voltage, which can have different values depending on the number of supply phases. The supply voltage ranges from 230 to 500V AC.

  • output voltage - phase-to-phase voltage dependent on the supply voltage, it ranges from 230 to 500V AC. When designing a process line, it is worth paying attention to the number of inverter outputs, operating temperature and IP rating. In addition, note that inverters can be programmed using different methods, e.g. a computer, potentiometer, or device keyboard.

How to select power supply cables for inverters

Selecting the right cabling for your motor equipment is important to ensure stability and reliability. The cables connecting the frequency inverters to the motor must be electromagnetically compatible and must withstand the accidental load that the cables may be subjected to in everyday operation.

Selecting the wiring for the inverter is not easy for everyone, so use the data provided by the manufacturer. The table is based on the inverter power (kW), to which a range of products with the most favourable conductor cross-section (mm) has been assigned.

Inverter power (kW) Conductor cross-section (mm2)
up to 1.5 1.5
1.5-3 2.5
3-7.5 4
7.5-11 6
11-18.5 10
18.5-22 16
22-30 25
30-37 35
37-45 50
45-75 70
75-90 95
90-110 120

Inverters available at TME

TME offer includes inverters manufactured by Schneider Electric, Siemens, Eaton Electric or Invertek Drives and dedicated Helukabel power supply cables for motors and frequency converters. For customers who have already chosen the inverter, the system automatically prompts the appropriate power cord. These are TOPFLEX series cables selected based on the power of the device.