Lenze 8200 Vector Selection

7.2 Fixed Frequency Selection (JOG)

Select three preset frequencies (such as 20 Hz, 30 Hz, 40 Hz) through two digital inputs (such as terminals 11/12), suitable for multi speed applications.

7.3 Pressure Control (PID)

Using an internal process controller, the pressure setting value is provided by a 4-20 mA signal from the PLC, and the actual pressure is fed back by a 0-10 V sensor. Configurable manual/automatic switching, night time voltage reduction operation (fixed frequency), minimum frequency anti dry rotation, frequency hopping to avoid mechanical resonance.

7.4 Group drive (parallel connection of multiple motors)

In V/f control mode, one frequency converter can drive multiple parallel motors. The total current shall not exceed the rated current of the frequency converter. Each motor needs to be connected in series with a thermal switch (NC contact) connected to the PTC input terminal (terminals T1/T2) of the frequency converter to achieve collective protection.

7.5 Sequential switching

For example, two refrigeration compressors: compressor 1 is controlled by a frequency converter for speed regulation, and when the demand increases, compressor 2 is directly started by outputting K1 through a relay (power frequency). Utilize the programmable relay delay function of the application I/O module to avoid frequent switching.

Common selection errors and precautions

Neglecting the requirements for incoming reactors: Some models (such as single-phase 230V 1.5 kW or above) must use reactors, otherwise it may damage the rectifier or cause harmonic exceedance.

Blind increase in carrier frequency: Increasing the carrier frequency can reduce motor noise, but it will significantly reduce the output current capability. Priority should be given to using 8 kHz (Lenze default), and only increase to 16 kHz and downgrade when necessary.

Improper selection of braking resistor: It is necessary to confirm that the resistance value is not lower than the minimum value allowed by the frequency converter (such as 0.55 kW 400V minimum 455 Ω), and the continuous power and thermal capacity need to match the braking cycle.

Improper filter combination: When using LD type RFI filters, motor filters must be used simultaneously to achieve the EMC limit for long cables. The Mains filter already includes an incoming reactor and does not require an external reactor.

Insufficient thermal resistance of cold plate technology: The thermal resistance of the user's own radiator must be less than the specified value, otherwise the frequency converter will be protected against overheating.