Causes

Possible Solutions

The drive and motor system are at the torque limit or current suppression will not let the drive accelerate.

  • Decrease the load.

  • Use a larger motor.

    Note:

    Although the drive has a Stall Prevention function and a Torque Compensation Limit function, if you try to accelerate too fast or try to drive a load that is too large, it can be too much for the limits of the motor.

Torque limit is set incorrectly.

Set the torque limit correctly.

The acceleration time setting is too short.

Examine the values set in C1-01, C1-03, C1-05, or C1-07 [Acceleration Time] and set them to applicable values.

The load is too large.

  • Increase the acceleration time.

  • Examine the mechanical brake and make sure that it is fully releasing.

  • Decrease the load to make sure that the output current stays less than the motor rated current.

  • Use a larger motor.

    Note:

    • In extruder and mixer applications, the load can increase as the temperature decreases.

    • Although the drive has a Stall Prevention function and a Torque Compensation Limit function, if you try to accelerate too fast or try to drive a load that is too large, it can be too much for the limits of the motor.

The frequency reference is low.

  • Examine E1-04 [Maximum Output Frequency] and increase the setting if it is set too low.

  • Examine U1-01 [Frequency Reference] for the correct frequency reference.

  • Examine the multi-function input terminals to see if a frequency reference signal switch is set.

  • When you use an MFAI, examine the low gain level set in H3-03, H3-11 [Terminal A1, A2 Gain Setting].

The frequency reference is set incorrectly.

When H3-10 = 1 Terminal A2 Function Selection = Frequency Gain], see if the drive is set for voltage (current).

  • Examine the value set in H3-10.

  • Use U1-14 [Terminal A2 Input Voltage] to make sure that the analog input value set to terminal A2 is applicable.

The motor characteristics and drive parameter settings are not compatible.

  • Set the correct V/f pattern to agree with the characteristics of the motor.

  • Examine the V/f pattern set in E1-03 [V/f Pattern Selection].

  • Do Rotational Auto-Tuning.

The drive is operating in vector control mode, but you did not complete Auto-Tuning.

  • Do Auto-Tuning.

  • Calculate motor data and reset motor parameters.

  • Set A1-02 = 0 [Control Method Selection = V/f Control].

The Stall Prevention level during acceleration setting is too low.

Increase the value set in L3-02 [Stall Prevent Level during Accel].

Note:

If the L3-02 value is too low, the acceleration time can be unsatisfactorily long.

The Stall Prevention level during run setting is too low.

Increase the value set in L3-06 [Stall Prevent Level during Run].

Note:

If the L3-06 value is too low, speed will decrease before the drive outputs torque.

The drive is at the limit of the V/f motor control method.

  • When the motor cable is longer than 50 m (164 ft), do Auto-Tuning for line-to-line resistance.

  • Set the V/f pattern to “High Starting Torque”.

  • Use a Vector Control method.

    Note:

    V/f control method does not supply high torque at low speeds.