Справочник Пользователя для Mitsubishi Electronics FR-A700

When Advanced magnetic flux vector control, Real sensorless vector control, vector control or encoder feedback control is
exercised, the output frequency varies with load fluctuation between 0 and 2Hz. This is a normal operation and is not a fault.

Load varies during an operation.

Select Advanced magnetic flux vector control, Real 
sensorless vector control, vector control, or encoder 
feedback control. 

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Frequency setting signal is varying.

Check the frequency setting signal.

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The frequency setting signal is affected by EMI.

Set filter to the analog input terminal using Pr. 74 Input 
filter time constant, Pr. 822 Speed setting filter 1. 

Take countermeasures against EMI, such as using 
shielded wires for input signal lines.

Malfunction is occurring due to the undesirable current 
generated when the transistor output unit is connected.

Use terminal PC (terminal SD when source logic)  as a 
common terminal to prevent a malfunction caused by 
undesirable current.

Multi-speed command signal is chattering.

Take countermeasures to suppress chattering.

—

Feedback signal from the encoder is affected by EMI.

Place the encoder cable far from the EMI source such 
as main circuit and power supply voltage.
Earth (ground) the shield of the encoder cable to the 
enclosure using a metal P-clip or U-clip.

Fluctuation of power supply voltage is too large.

Change the Pr. 19 Base frequency voltage setting (about 
3%) under V/F control.

Pr.80 Motor capacity and Pr.81 Number of motor poles are 
not appropriate for the motor capacity under Advanced 
magnetic flux vector control, Real sensorless vector 
control, or vector control. 

Check the settings of Pr.80 Motor capacity and Pr.81 
Number of motor poles.

Wiring length exceeds 30m when Advanced magnetic 
flux vector control, Real sensorless vector control, or 
vector control is selected.

Perform offline auto tuning.

Wiring length is too long for V/F control, and the a 
voltage drop occurs.

Adjust the Pr. 0 Torque boost setting by increasing with 
0.5% increments for the low-speed operation.

Change the control method to Advanced magnetic flux 
vector control or Real sensorless vector control.

Hunting occurs by the generated vibration, for example, 
when structural rigidity at load side is insufficient.

Disable automatic control functions, such as the energy 
saving operation, the fast-response current limit function, 
the torque limit, the regeneration avoidance function, 
Advanced magnetic flux vector control, Real sensorless 
vector control, vector control, encoder feedback control, 
droop control, the stall prevention, online auto tuning, the 
notch filter, and orientation control. 
During the PID control, set smaller values to Pr.129 PID 
proportional band and Pr.130 PID integral time. 
Lower the control gain, and adjust to increase the 
stability.

—

Change Pr. 72 PWM frequency selection setting.