Acceleration/Deceleration Is Not Smooth; Motor Current Is Large; Speed Does Not Increase; Speed Varies During Operation - Mitsubishi Electric FR-A700 Instruction Manual

Troubleshooting
7.6.6

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.
● Check that the torque boost (Pr. 0, Pr. 46, Pr. 112) setting is not too large to activate the
stall function.
7.6.7

Motor current is large

● Check that the load is not too heavy.
● Check that the Pr. 0 "Torque boost" setting is correct.
● Check that the Pr. 3 "Base frequency" setting is correct.
● Check that the Pr. 14 "Load pattern selection" setting is appropriate.
● Check that the Pr. 19 "Base frequency voltage" is correct.
7.6.8

Speed does not increase

● Check that the maximum frequency (Pr. 1) setting is correct. (If you want to run the motor
at 120 Hz or more, set Pr. 18 "High speed maximum frequency".) (Refer to the section 6.8.1.))
● If you are using analog set point signals check whether the gain (Pr. 125 and Pr. 126) is set
correctly.
● Check that the load is not too heavy.
(In agitators, etc., load may become heavier in winter.)
● Check that the torque boost (Pr. 0, Pr. 46, Pr. 112) setting is not too large to activate the
stall function.
● Check that the brake resistor is not connected to terminals P/+ and P1 accidentally.
7.6.9

Speed varies during operation

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 be-
tween 0 and 2Hz. This is a normal operation and is not a fault.
● Inspection of load
– Check that the load is not varying.
● 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" and Pr. 822 "Speed setting filter 1".
– Check for a malfunction due to undesirable currents when the transistor output unit is
connected. (Refer to page 3-25.)
FR-A700 EC
Check first when you have troubles
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