TOSHIBA TOSBERT VF-A3 frequency converter

The consequences of ignoring restrictions:

Insufficient ventilation can cause the frequency converter to overheat (fault code OH), triggering a protective shutdown and potentially damaging the power module in the long run.

Excessive humidity/condensation can cause a short circuit and ground fault (EF code) in the main circuit.

Excessive vibration may cause loose terminals, poor contact leading to overcurrent (OC code) or equipment shutdown.

Question 2: In the daily operation of VF-A3 frequency converter, how to set the "DC injection braking" function through the panel to achieve precise motor stop? It is necessary to clarify the setting range and default values of key parameters.

Answer: The steps and key parameters for setting "DC injection braking" through the panel are as follows:

Enter the second functional mode:

Press the "MON" button, and the display will show "no.0 →: t: JP"; Press the "2ND" key to switch to the "2nd" mode.

Select DC injection braking related parameters (function number 0, Table 3.1):

Parameter Name Function Setting Range Default Value Operation Instructions

When the DBF (DC injection braking start frequency) motor drops to this frequency, it triggers the braking 0-10Hz (0.1Hz step size) 0Hz. Press "READ" to read the current value, press "△/▽" or the numerical key to adjust, and press "WRT" to save

DBU (DC injection braking voltage) injects a DC voltage that accounts for 0-20% (1% step size) during braking. If the voltage is too high, it will cause the motor to overheat. It is recommended to adjust according to the inertia of the load (such as 10% -15%)

DBT (DC injection braking time) braking duration 0-5 seconds (0.1 second step) 0 seconds. It is necessary to ensure that the time is sufficient to stop the motor and avoid incomplete braking caused by too short a time

Confirm settings: Press the "MON" key to return to the original display (frequency/OFF), and the settings will take effect.

Attention: DC injection braking is only activated during deceleration and stopping process, and should be accompanied by appropriate deceleration time (DEC) to avoid triggering overcurrent protection due to excessive current during braking.

Question 3: What are the possible reasons when the VF-A3 frequency converter displays "OC1" (acceleration overcurrent) fault? What are the corresponding solutions? What safety precautions should be taken during troubleshooting?

Answer:

Reason for "OC1" fault: During acceleration, the main circuit current exceeds the protection threshold. Common reasons include:

The acceleration time (ACC) is set too short, and the motor speed cannot keep up with the frequency increase, resulting in excessive stalling current.

The torque boost (ub) is set too high, causing overcurrent due to high voltage during startup.

Sudden load changes in the motor (such as sudden blockage of the conveyor), and the load current exceeds the rated output of the frequency converter.

Poor wiring of the main circuit (such as loose wiring at the motor end) can cause current fluctuations.

Solution:

Extend acceleration time: Enter the first function ("MON" → select function number 2), adjust "ACC1/ACC2" to a longer time (such as changing from 1 second to 3 seconds), and press "WRT" to save.

Reduce torque boost: Enter the first function (function number 1), reduce the "ub" value (such as from 10% to 5%), and avoid starting overvoltage.

Check the load: Check if the mechanical load is stuck, clean up foreign objects or reduce the load to ensure that the load is within the rated range of the motor.

Check wiring: Disconnect the power supply (MCCB), confirm that the "CHARGE" light is off, tighten the terminal screws of the main circuit (L1/R, T1/U, etc.), and check the insulation of the circuit.

Check safety precautions:

Before checking all wiring, the main switch of the distribution panel must be disconnected and wait for the "CHARGE" light to turn off (to avoid electric shock caused by residual voltage of the capacitor).

When adjusting parameters, it is necessary to ensure that the frequency converter is in a stopped state. Modifying acceleration time/torque increase during operation may cause equipment instability.

If the fault still exists after multiple troubleshooting, it is necessary to check the motor insulation (using a 500V megohmmeter) to avoid overcurrent caused by internal short circuit of the motor.