Speed Greatly Differs From The Setting; Acceleration/Deceleration Is Not Smooth; Motor Current Is Large; Speed Does Not Increase - Mitsubishi Electric FR-B-750 to 75K Instruction Manual

Check first when you have troubles

5.5.5 Speed greatly differs from the setting

Check that the frequency setting signal is correct. (Measure the input signal level.)
Check that the Pr. 1, Pr. 2, Calibration parameter C2 to C7 settings are correct
Check that the input signal lines are not affected by external noise. (Use shielded cables)
Check that the load is not too heavy.
Check that the Pr. 31 to Pr. 36 (frequency jump) settings are correct.

5.5.6 Acceleration/deceleration is not smooth

Check that the acceleration and deceleration time settings are not too short.
Check that the load is not too heavy.

5.5.7 Motor current is large

Check that the load is not too heavy.

5.5.8 Speed does not increase

Check that the Pr. 1 Maximum frequency setting is correct.
Check that the load is not too heavy. (In agitators, etc., load may become heavier in winter.)

5.5.9 Speed varies during operation

When the FR-B3 series, 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.
1) Inspection of load
Check that the load is not varying.
2) Check the input signals
Check that the frequency setting signal is not varying.
Check that the frequency setting signal is not affected by noise. Input filter to the analog input
terminal using Pr. 74 Input filter time constant.
Check for a malfunction due to undesirable currents when the transistor output unit is connected.
(Refer to page 30)
3) Others
Check that the settings of Pr. 80 Motor capacity and Pr. 81 Number of motor poles are correct to the
inverter capacity and motor capacity under FR-B3 series.
For the FR-B3 series, perform offline auto tuning. (Refer to pege 70)
Check that the wiring length is not too long for V/F control.(FR-B series only)

5.5.10 Operation mode is not changed properly

If the operation mode does not change correctly, check the following:
1) Inspection of load
Check that the STF or STR signal is off.
When it is on, the operation mode cannot be changed.
2) Parameter setting
Check the Pr. 79 setting.
When the Pr. 79 Operation mode selection setting is "0" (initial value), the inverter is placed in the
external operation mode at input power-on. At this time, press
when the parameter unit (FR-PU04/FR-PU07) is used) to switch to the PU operation mode.
For the other values (1 to 4, 6, 7), the operation mode is limited accordingly.
280
on the operation panel (press