Toshiba VF-A7 How to check other troubles, Measures against trouble with parameter setting

12. 4 How to check other troubles

Expected causes of other troubles (abnormal operations and conditions) and measures to settle those troubles are shown below.

Abnormal	Causes and measures
operation/condition

	･Change phase sequence of output terminals U, V and W.
Motor runs reversely.	･Change forward and reverse signal inputs of external operation signals for
	each other. (Refer to 7.2, Control terminal function allotment.)
	･Load to motor is too heavy.
	Reduce the load.
	･Soft stall function is activated.
	Switch off soft stall function. (Refer to 5.13.)
	･Setting values of maximum frequency  and upper limit frequency 
	are low.
Motor runs but speed	Raise maximum frequency and upper limit frequency  to higher
	level.
cannot be varied.	･Frequency setting signal is low (weak).
	Check input level of signal, circuit and connection, etc.
	･Check setup specifications of frequency setting signal (setting of point 1,
	point 2). (Refer to 7.3.)
	･Check to see if stall prevention function is activated at low-speed operation
	because of too high torque boost rate.
	Adjust manual torque boost () and acceleration time #1 (). (Refer
	to 5.12 and 5.1.)
Acceleration/deceleration	･Acceleration time #1 () and deceleration time #1 () are set short.
of motor is rough.	Increase setting values of acceleration time #1 () and deceleration
	time #1 ().
	･Load to motor is too heavy.
Large motor current	Reduce load to motor.
	･Check to see if torque boost rate is too high at low-speed operation. (Refer
	to 5.12.)
	･Improper voltage setting for the motor.
	Set voltage properly to the motor.
	･Terminal voltage of the motor is low.
Motor speed is high or	Check setting value of base frequency voltage #1 (). (Refer to
	6.13.6.) Change the cable for thicker one.
low.	･Improper gear ratio for acceleration and deceleration.
	Change gear ratio properly for smooth acceleration and deceleration.
	･Output frequency is set improperly.
	Check setup of output frequency range.
	･Tune basic frequency. (Refer to 5.9.)
	･Load to the motor is too heavy or light.
	Reduce load fluctuation.
Motor speed varies in	･Rating of inverter or motor is improper to load.
	Change the motor or inverter for another of higher rating.
operation.
	･Check to see if frequency setting signal input fluctuates.
	･If V/f control parameter is set at 3 or larger, check setting value and setup
	conditions of vector control. (Refer to 5.10.)
Some or all of six keys	･Change panel operation prohibition parameter . (Refer to 6.30.14.)
on operation panel don't	*Parameter is occasionally set for key operation prohibition mode. Cancel
work.
	key operation prohibition mode according to the following procedure.
Access to parameter
	Press the [△] key twice while pressing the [ENT] key.
results in failure.
	1: If parameter setting prohibition parameter is set at ""(prohibited),
Parameter cannot be
changed.	change the setting to "" (allowed).
Monitor (display) is	2: If there is an input terminal that is set for "" (or "") (parameter
uncontrollable.	editing enabling) by input terminal function parameter, turn on the terminal.

Measures against trouble with parameter setting

How to check the	･ Changed parameters can be searched and reset.
parameters that have
	For details, refer to 4.1.3.
been changed.
How to reset changed	･ Parameters whose values have been changed can be reset to their
parameters to default	respective default values in bulk.
values	For details, refer to 4.1.5.

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