Toshiba VF-S9 manual How to determine the causes of other problems, E6580757

E6580757

13.4 How to determine the causes of other problems

The following table provides a listing of other problems, their possible causes and remedies.

Problems			Causes and remedies
The motor runs in the	•	Invert the phases of the output terminals U, V and W.
wrong direction.	•	Invert the forward/reverse run-signal terminals of the external input device. (See
		6.3 "Assignment of functions to control terminals".)
The motor runs but its	•	The load is too heavy.
speed does not change		Reduce the load.
normally.	•	The soft stall function is activated.
		Disable the soft stall function. (See 5.14.)
	•	The maximum frequency	and the upper limit frequency		are set too low.
		Increase the maximum frequency		and the upper limit frequency		.
	• The frequency setting signal is too low.
		Check the signal set value, circuit, cables, etc.
	• Check the setting characteristics (point 1 and point 2 settings) of the frequency
		setting signal parameters. (See 6.5.)
	• If the motor runs at a low speed, check to see that the stall prevention function is
		activated because the torque boost amount is too large.
		Adjust the torque boost amount (		) and the acceleration time (		). (See
		5.12 and 5.1.)
The motor does not ac-	•	The acceleration time (	) or the deceleration time (		) is set too short.
celerate or decelerate		Increase the acceleration time (		) or the deceleration time (		).
smoothly.
A too large current flows	•	The load is too heavy.
into the motor.		Reduce the load.
	• If the motor runs at a low speed, check whether the torque boost amount is too
		large. (See 5.13.)
The motor runs at a	•	The motor has an improper voltage rating.
higher or lower speed		Use a motor with a proper voltage rating.
than the specified one.	•	The motor terminal voltage is too low.
		Check the setting of the base frequency voltage parameter (				). (See
		6.12.6.)
		Replace the cable with a cable larger in diameter.
	• The reduction gear ratio, etc., are not set properly.
		Adjust the reduction gear ratio, etc.
	• The output frequency is not set correctly.
		Check the output frequency range.
	• Adjust the base frequency. (See 5.11.)
The motor speed fluctu-	•	The load is too heavy or too light.
ates during operation.		Reduce the load fluctuation.
	• The inverter or motor used does not have a rating large enough to drive the
		load.
		Use an inverter or motor with a rating large enough.
	• Check whether the frequency setting signal changes.						13
	•	If the V/F control selection parameter		is set at 3, check the vector control
		setting, operation conditions, etc. (See 5.12.)
Parameter settings can-	•	Change the setting of the parameter		(prohibition of change of parameter
not be changed.		setting) to (permitted) if it is set at		(prohibited).
		For reasons of safety, some parameters cannot be reprogrammed while the
		inverter is running.

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