Troubleshooting
Troubleshooting
Due to parameter setting errors, faulty wiring, and so on, the Inverter and motor may not operate as expected when the system is started. If that occurs, use this section as a reference and perform the appropriate countermeasures.
If the contents of the fault are displayed, refer to
page 6-2, Protective and Diagnostic Functions
.
If A Parameter Cannot Be Set
Use the following information if a parameter cannot be set.
The display does not change when the Increment and Decrement keys are pressed.
The following causes are possible:
The Inverter is operating (drive mode).
There are some parameters that cannot be set during operation. Turn off the RUN command and then set the parameters
Passwords do not match. (Only when a password is set.)
If the parameter A1-04 (Password) and A1-05 (Password Setting) settings are different, the parameters for the initialize mode cannot be changed. Enter the correct password in A1-04.
If you cannot remember the password, display A1-05 (Password Setting) by pressing the Shift/RESET key and the MENU key simultaneously while in the A1-04 display. Then set the password and input the set password in parameter A1-04.
OPE01 through OPE11 is displayed.
The set value for the parameter is wrong. Refer to
Table 6.23
in this chapter and correct the settings.
CPF00 or CPF01 is displayed.
This is a Digital Operator/Monitor communication error. The connection between the Digital Operator/Monitor and the Inverter may be faulty. Remove the Digital Operator/Monitor and then re-install it.
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If the Motor Does Not Operate Properly
The following causes are possible:
The motor does not operate when an external operation signal is input.
The frequency reference is 0.00 Hz or a no speed is selected by the digital inputs. Check the input signals and the frequency reference settings.
Also make sure to set the Baseblock signal. The inverter does not accept any input if it is base blocked.
The load is too heavy
Check the motor current. If it is at the limit of the inverter rated current the load might be too high. Check the inverter size and the mechanical system. Check also if the brake is operating or not.
If the Direction of the Motor Rotation is Reversed
If the motor rotates in the wrong direction, the motor output wiring may be incorrect. When the Inverter operates in the forward direction, the forward direction of the motor will depend on the manufacturer and the motor type, so be sure to check the motor specification
The direction of the motor rotation can be reversed by switching two wires among U, V, and W. If using an encoder, the polarity will also have to be switched. If the Inverter is operated in V/f mode also parameter b1-
04 can be used to change the rotation direction.
If the Motor Stalls or Acceleration is Slow
The torque limit has been reached.
When a torque limit has been set in parameters L7-01 to L7-04, the output torque will be limited according these settings. Therefore the motor may not develop enough torque to accelerate or the acceleration time might be very long.
The stall prevention level during acceleration is too low.
If the value set for L3-02 (Stall Prevention Level during Acceleration) is too low, the acceleration time will be increased. Check that the set value is suitable and that the load is not too large for the motor.
The stall prevention level during running is too low.
If the value set for L3-06 (Stall Prevention Level during Running) is too low, the motor speed and torque will be limited. Check that the set value is suitable and that the load is not too large for the motor.
Auto-tuning has not been performed for vector control
Vector control will not work properly if auto-tuning has not been performed. Perform auto-tuning, or set the motor parameters through calculations.
Troubleshooting
If Motor Deceleration is Slow
The following causes are possible:
The deceleration time is too long
The following causes are possible:
The deceleration time setting is too long.
Check the deceleration time setting (parameters C1-02, C1-04, C1-06, and C1-08).
Motor torque is insufficient.
If the parameters are correct and there is no overvoltage fault, then the motor's power may be insufficient.
Consider increasing the motor and Inverter capacity.
The torque limit has been reached.
When a torque limit is reached (L7-01 to L7-04), the motor torque will be limited. This can cause the deceleration time to be extended. Check to be sure that the value set for the torque limit is suitable.
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If the Motor Overheats
The following causes are possible:
The load is too large.
If the motor load is too large and the torque exceeds the motor’s rated torque, the motor may overheat. Reduce the loads by either reducing the load or increasing the acceleration/deceleration times. Also consider increasing the motor size.
The ambient temperature is too high.
The motor rating is determined by a particular ambient operating temperature range. The motor will overheat if it is run continuously at the rated torque in an environment where the maximum ambient operating temperature is exceeded. Lower the motor's ambient temperature to be within its acceptable range.
Auto-tuning has not been performed for vector control
Vector control may not perform efficiently if auto-tuning has not been performed. Perform auto-tuning, or set the motor parameters through hand calculations. Alternatively, change the Control Mode Selection (A1-02) to
V/f Control (0 or 1).
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If Peripheral Devices are Influenced by the Starting or Running Inverter
The following solutions are possible:
•
Change the Inverter's Carrier Frequency Selection (C6-02) to lower the carrier frequency. This will help to reduce the amount of transistor switching noise.
•
•
•
•
•
Install an Input Noise Filter at the Inverter's input power terminals.
Install an Output Noise Filter at the Inverter's motor terminals.
Use shielded motor cables or a conduit. Metal shields electrical noise.
Check the grounding of the Inverter and motor.
Separate main circuit wiring from control circuit wiring.
If the Earth Leakage Breaker Operates When the Inverter is Running
The Inverter’s output is pulse modulated, i.e. the output voltage consists of high frequency pulses (PWM).
This high frequency signal causes a certain amount of leakage current which may cause the earth leakage breaker to operate and cut off the power supply. Change to a ground fault interrupter with a high leakage detection level (i.e., a sensitivity current of 200 mA or higher, with an operating time of 0.1 s or more), or one that incorporates high frequencies countermeasures (i.e., one designed for use with Inverters). It will also help to some extent to lower the Inverter's Carrier Frequency Selection (C6-02). In addition, remember that the leakage current increases as the cable is lengthened.
Troubleshooting
If There is Mechanical Oscillation
Use the following information when there is mechanical vibration:
Oscillation and hunting occur with V/f control
The torque compensation parameter settings may be incorrect for the machine. Adjust parameters C4-01
(Torque Compensation Gain) and C4-02 (Torque Compensation Delay Time). Decrease C4-01 carefully in steps of 0.05 and/or increase C4-02.
Furthermore the Slip Compensation Delay Time (C3-02) can be decreased.
Oscillation and hunting occur with Open Loop Vector control.
The torque compensation parameter settings may be incorrect for the machine. Adjust parameters C4-01
(Torque Compensation Gain), C4-02 (Torque Compensation Delay Time Parameter) and C3-02 (Slip Compensation Delay Time) in order. Lower the gain parameters and raise the delay time parameters.
If auto-tuning has not been performed, proper performance may not be achieved for Vector Control. Perform auto-tuning or set the motor parameters through hand calculations.
Oscillation and hunting occur with Closed Loop Vector control
The gain adjustment may be insufficient. Adjust the speed control loop (Automatic Speed Regulator, ASR) by changing C5- gain parameters. If the oscillation points overlap with those of the machine and cannot be eliminated, increase the ASR Delay Time, and then readjust the ASR gains.
If auto-tuning has not been performed, proper performance may not be achieved for Closed Loop Vector Control. Perform auto-tuning or set the motor parameters through hand calculations.
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Maintenance and
Inspection
This chapter describes basic maintenance and inspection for the Inverter
Maintenance and Inspection........................................7-2
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