Variable Frequency Drives (VFDs), hereinafter referred to as VFD, are devices capable of speed regulation and energy conservation. Their extensive use in mechanical, chemical, metallurgical, and light industrial fields, among others, results from their high-speed control precision, ease of operation, and energy efficiency (particularly when the output frequency is below 50Hz). This article explains several characteristics of VFD frequency setting methods according to practical application needs.
There are two main types of VFD frequency setting methods.
The first type involves using the VFD’s control panel for frequency adjustment, while the second type employs a VFD control terminal.
The first method, using the VFD control panel for frequency setting, allows frequency adjustment only through the up and down keys on the control panel. This method doesn’t require external wiring, is simple, and offers high-frequency setting precision. It is a form of digital frequency setting suitable for single VFD frequency adjustment.
The second method involves using a VFD control terminal to set the frequency and is further divided into two approaches. The first approach uses an external potentiometer to set the frequency, while the second utilizes a unique feature of VFD control terminals by using an electric potentiometer for frequency setting.
The first method utilizes an external potentiometer for frequency adjustment, specifically designed for the AFSV60 series VFD. This series features ten terminals that supply a standard 10V DC voltage. Among these terminals, two are designated for inputting frequency settings, while the remaining five function as common analog input terminals. This approach involves adjusting the external potentiometer’s output voltage at terminals ‘R,’ which, in turn, alters the input voltage values at terminal ‘2’ of the VFD. Consequently, the VFD’s frequency setting is modified to achieve the desired frequency setting. This method presents several advantages:
Simple wiring: Merely connect the three terminals of the potentiometer to the VFD’s voltage input, voltage output, and common terminals.
Easy frequency setting: Frequency setting is as simple as gently rotating the knob of the external potentiometer.
Regarding installation flexibility, you can position the external potentiometer remotely at any location based on your specific requirements.
However, this method also has its drawbacks:
Temperature drift can occur due to variations in external temperatures, affecting the resistance values and subsequently impacting the frequency setting values.
Low interference resistance: When strong electromagnetic interference is present in the vicinity, induced voltage may arise in the connection cable between the VFD and the external potentiometer. This can alter the voltage input to VFD terminal ‘2’, resulting in instability in the set frequency.
Limited potentiometer installation distance: In theory, the voltage variation range for VFD terminal ‘2’ is 0-10V. Placing the external potentiometer too far away can result in cable voltage drop. This can hinder VFD terminal ‘2’ from reaching 10V and, consequently, limit the output frequency from reaching its maximum set value.
As a result, the VFD frequency setting method is generally suitable for applications where precision in speed regulation, low interference, and minimal environmental temperature fluctuations are present. This method falls under analog regulation.
The second method involves using VFD’s specific functions to control terminals. By configuring the internal parameters of the VFD, terminals RH and RM can act as a variable resistor. When RH connects to the common terminal SD, the VFD’s output frequency increases, and when RM connects to SD, the output frequency decreases, achieving the frequency setting objective.
Compared to the first method:
High-frequency setting precision: Employing an external potentiometer is classified as an analog setting approach, resulting in frequency variations within ±0.2% of the maximum output frequency. Conversely, the use of an electric potentiometer for frequency setting maintains frequency variations within ±0.01% of the maximum output frequency.
Strong interference resistance: It’s not affected by surrounding electromagnetic fields as it only involves switch signal input.
No temperature drift: The absence of an external potentiometer eliminates the impact of environmental temperature changes.
Flexible installation: Buttons SB1 and SB2 can be placed in any location.
Excellent synchronization performance: You can simultaneously increase or decrease multiple sets of VFD frequencies.
In summary, it’s essential to choose frequency setting methods that align with specific application requirements to attain the desired outcomes.
Variable Frequency Drives (VFDs), hereinafter referred to as VFD, are devices capable of speed regulation and energy conservation. Their extensive use in mechanical, chemical, metallurgical, and light industrial fields, among others, results from their high-speed control precision, ease of operation, and energy efficiency (particularly when the output frequency is below 50Hz). This article explains several characteristics of VFD frequency setting methods according to practical application needs.
There are two main types of VFD frequency setting methods.
The first type involves using the VFD’s control panel for frequency adjustment, while the second type employs a VFD control terminal.
The first method, using the VFD control panel for frequency setting, allows frequency adjustment only through the up and down keys on the control panel. This method doesn’t require external wiring, is simple, and offers high-frequency setting precision. It is a form of digital frequency setting suitable for single VFD frequency adjustment.
The second method involves using a VFD control terminal to set the frequency and is further divided into two approaches. The first approach uses an external potentiometer to set the frequency, while the second utilizes a unique feature of VFD control terminals by using an electric potentiometer for frequency setting.
The first method utilizes an external potentiometer for frequency adjustment, specifically designed for the AFSV60 series VFD. This series features ten terminals that supply a standard 10V DC voltage. Among these terminals, two are designated for inputting frequency settings, while the remaining five function as common analog input terminals. This approach involves adjusting the external potentiometer’s output voltage at terminals ‘R,’ which, in turn, alters the input voltage values at terminal ‘2’ of the VFD. Consequently, the VFD’s frequency setting is modified to achieve the desired frequency setting. This method presents several advantages:
Simple wiring: Merely connect the three terminals of the potentiometer to the VFD’s voltage input, voltage output, and common terminals.
Easy frequency setting: Frequency setting is as simple as gently rotating the knob of the external potentiometer.
Regarding installation flexibility, you can position the external potentiometer remotely at any location based on your specific requirements.
However, this method also has its drawbacks:
Temperature drift can occur due to variations in external temperatures, affecting the resistance values and subsequently impacting the frequency setting values.
Low interference resistance: When strong electromagnetic interference is present in the vicinity, induced voltage may arise in the connection cable between the VFD and the external potentiometer. This can alter the voltage input to VFD terminal ‘2’, resulting in instability in the set frequency.
Limited potentiometer installation distance: In theory, the voltage variation range for VFD terminal ‘2’ is 0-10V. Placing the external potentiometer too far away can result in cable voltage drop. This can hinder VFD terminal ‘2’ from reaching 10V and, consequently, limit the output frequency from reaching its maximum set value.
As a result, the VFD frequency setting method is generally suitable for applications where precision in speed regulation, low interference, and minimal environmental temperature fluctuations are present. This method falls under analog regulation.
The second method involves using VFD’s specific functions to control terminals. By configuring the internal parameters of the VFD, terminals RH and RM can act as a variable resistor. When RH connects to the common terminal SD, the VFD’s output frequency increases, and when RM connects to SD, the output frequency decreases, achieving the frequency setting objective.
Compared to the first method:
High-frequency setting precision: Employing an external potentiometer is classified as an analog setting approach, resulting in frequency variations within ±0.2% of the maximum output frequency. Conversely, the use of an electric potentiometer for frequency setting maintains frequency variations within ±0.01% of the maximum output frequency.
Strong interference resistance: It’s not affected by surrounding electromagnetic fields as it only involves switch signal input.
No temperature drift: The absence of an external potentiometer eliminates the impact of environmental temperature changes.
Flexible installation: Buttons SB1 and SB2 can be placed in any location.
Excellent synchronization performance: You can simultaneously increase or decrease multiple sets of VFD frequencies.
In summary, it’s essential to choose frequency setting methods that align with specific application requirements to attain the desired outcomes.
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