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Lichuan ac servo motor using FAQ

Time:2021-01-14 Views:413
Lichuan A4 and B2 AC servo motor using FAQ

1. How to connect the servo motor power supply?

Answer: For B2, you can directly connect 220V to R/S; A4 servo connects L1 and L1C to 220V L line, and L2 and L2C to 220V N line.


2. Commonly used wiring method for servo motor position mode?

Answer: The CN3 port of B2 series servo is connected to 1DIR-/2PUL-/3DIR+/4DIR- (24V signal needs to be connected with 1.5K resistor on the negative terminal); the CN3 port of A4 series servo is connected to 1PUL-/16DIR-/2PUL+/17DIR+ (built-in connection method) 16 and 17 do not need to be connected, directly connected to 35 feet; external connection of 24V requires a 1.5K resistor in the negative terminal).

3. After the servo is powered on, the motor runs automatically without pulses?

Answer: 1. B2 series: check whether the PR1.00 parameter is 1; A4 series: check whether PA-02 is 0; 2. Ensure good protective grounding
3. The driver power input line L and N end use filter to filter.
4. Connect 103 ceramic capacitors in parallel between Pul/Dir +-.

4. When the PLC controls the servo by pulse + direction, what is the reason why the motor can only rotate in one direction?

Answer: ①The line error caused the drive to not receive the direction signal; ②The optocoupler of the drive receiving the direction signal is burned out. The normal input voltage of this circuit is 5V. If you accidentally connect the 12V or 24V pulse signal, the direction signal is basically normal. It is easier to burn out than the circuit that receives the pulse.

5. When the servo is working in torque mode, will the motor be damaged if the motor is driven by an external force in the opposite direction to the motor output for a long time?

Answer: This operating condition will not cause damage to the motor. Will report that the bus voltage is too high

6. Is there any problem with the servo motor working above the rated speed for a long time?

Answer: Each motor has a corresponding characteristic curve. The output torque of the servo motor above the rated speed must be less than the rated speed. In addition, the service life of the mechanical part of the motor running above the rated speed for a long time will be affected.

7. What should be paid attention to before the servo is powered on?

Answer ①Whether the power supply voltage is appropriate, overvoltage will cause damage to the drive module;
②Don‘t start to connect all the wires you need, only connect the most basic system. After the operation is good, connect gradually.

8. When the servo test machine is powered on, the motor vibrates and makes a lot of noise, and then the servo alarms. How to solve it?

Answer: This phenomenon is caused by the excessively high gain setting of the driver, which produces self-oscillation. Please adjust the parameters to reduce the rigidity of the system; or directly initialize the driver.

9. Why the parameters are restored to factory settings and the servo is powered on again but still not restored to the factory values?
Answer: Check whether the operation of the initialization step is normal. B2 series first cancel the enable, then set PR1.61 to 65535 and press the SET button to save and restart; A4 series: AF-ini and then press the SET button, "INI -" "Then press the up button often to display SEART, and press the arrow like left again to display Finish. That is complete. Power off and restart.

10. When an alarm occurs in the servo, can the alarm be cleared without power failure?

Answer: Only a few alarms can be cleared after power-on again. Most of the alarms can be cleared through DI. Please refer to Chapter 7.1 of the Technical Manual for details.

11. When the motor with brake is installed on the vertical Z-axis, when the servo-off, the machine head will drop a little before the brake is engaged. How to solve this problem?

Answer: In the correct wiring mode, the brake of the motor is controlled by the drive DO signal BRK-OFF to open and close. When the servo is on, the drive will output a signal to open the brake, and when the servo is off, the brake will be closed. Set the mechanical brake action PA-6B (B2 series PR1.26) to a value during operation, and the brake can be closed before the servo on is disconnected, so as to prevent the nose from falling down. (The brake must be controlled by an intermediate relay)

12. In normal use, the motor temperature is very high due to the high start-stop frequency. Will the motor be damaged if it is used for a long time?

Answer: The encoder of the servo motor will be damaged when the temperature reaches 85 degrees Celsius. Demagnetization will occur when the rotor temperature of the servo motor reaches 130 degrees Celsius or more. The temperature difference between the inside and outside of the servo motor is about 130 degrees when the surface temperature of the motor body is 85 degrees Celsius. When the servo motor starts and stops frequently, the temperature of the servo motor may be very high. At this time, it is necessary to take external forced cooling measures, such as adding a cooling fan, canceling the internal regenerative resistor, and installing a larger power regenerative resistor externally.

13. The servo is normal when it is turned on, and the controller does not send pulses when the power is off. Why does the servo motor move?

Answer: At the moment of power failure, high-frequency clutter may enter the servo drive through the control line. If the servo is still in the servo on state, the clutter will be regarded as a pulse command, so the servo motor will move. You can filter high frequency clutter by setting the parameter PA-07 (B2 series PR1.38).

14. Why does the motor not rotate during manual JOG?

Answer: The following conditions often cause the motor to not rotate when JOG through the drive:
  Servo enable servo onJOG must run without enabling;
  The UVW power line between the driver and the motor is not connected ;
  Wrong phase sequence connection of the UVW power line between the driver and the motor    causes an alarm;

15. What is the reason why the motor does not rotate when starting the servo?

Answer: The following conditions often cause the motor to not rotate when passing through the drive:
Run without the servo enable;
The UVW power line between the driver and the motor is not connected;
Wrong phase sequence connection of the UVW power line between the driver and the motor causes an alarm

16. What is the reason why the servo motor will sway back and forth after running with a load?

Answer: The load inertia is too large. First calculate the load inertia according to the mechanical structure parameters to see if it is larger than the motor inertia ratio (the load inertia ratio is generally within 10 times of the upper motor inertia). If the difference in inertia is not big, adjust the parameter PA-20 for the A4 series and PR5.18 for the B2 series.

17. Can the three-phase UVW output from the servo drive to the motor be interchangeable?

Answer: No, the connection method from the servo drive to the motor UVW is unique. Ordinary asynchronous motor input power UVW will reverse when the two exchanges, in fact, any two of the servo motor UVW will reverse, but the servo motor has a feedback device, so that positive feedback will cause the motor to runaway. The servo drive will detect and prevent running away, so after the UVW is connected to the wrong wire, we see the phenomenon that the motor rotates an angle at a very fast speed and then alarms.

18. What is the difference between a servo motor and an ordinary motor?

Answer: The biggest difference between a servo motor and an ordinary motor is the motor rotor and feedback device. The surface of the servo motor rotor is attached with strong magnetic steel sheets, so the position of the rotor can be accurately controlled by the magnetic field generated by the stator coil, and the acceleration and deceleration characteristics are much higher than that of ordinary motors. The feedback device can accurately feedback the rotor position of the motor to the servo drive. Common feedback devices for servo motors include optical encoders and resolvers.

19. How to choose the servo driver and motor?

Answer: Step 1: Determine the mechanical structure and calculate the load inertia (see the motor selection calculation table for details)
Step 2: Determine the load operating speed and calculate the motor speed.
Step 3: Compare the motor inertia and load inertia, and determine whether to use a reducer or similar equipment in combination with the motor speed.
Step 4: Convert the maximum load to the motor shaft to be within 10 times the inertia of the servo motor to determine the motor and drive model.

20. What are the functions and differences of ordinary encoders, single-turn absolute encoders, and multi-turn absolute encoders?

Answer: Ordinary encoders can not record the fixed number of pulses in one circle of feedback, and the single-turn absolute encoder can record the stopping angle of the motor in a certain circle in addition to the fixed number of pulses per circle. But it cannot record the number of motor running turns. The multi-turn absolute value encoder can record the number of motor running turns on the basis of the single-turn absolute value encoder, but it needs a built-in battery or other power supply equipment.

21. Servo motor rated speed n (r/s), current constant Kt (NM/A), rated power P (watts), and rated current I, the relationship between rated torque T (NM):

T=Kt*I
P=n*2π*T"

22. What should I do if the servo does not lock the axis?

Answer: 1. Check whether the servo enable parameter (A4 enable parameter PA-8F, B2 parameter PR6.01) is set to 1, if external enable, please check whether the wiring is correct; internal enable and external enable cannot be used at the same time. 2. Check whether the motor U/V/W line is well connected. 3. Check whether the function definition and distribution of the enabled DI port are normal.

23. Servo function button definition:

Answer: MODE (mode key:), switch between 5 modes. SET (set key): 1. Used to display mode and perform display switching. ▲ (increase key): increase numerical value or serial number. Change the display content in the mode, change the parameter, select the parameter or perform the selected operation ▼ (decrease key): Decrease the value or the serial number. Change the display content in the mode, change the parameter, select the parameter or perform the selected operation ◀ (Left shift key): Move the movable decimal point to the left (if the decimal point is at the highest digit, it can be moved to the lowest digit)

24. A4 servo drive restore factory settings steps:

Answer: A4 (A6) steps to restore factory settings: 1. After pressing the Set button, press the Mode button 4 times to switch to the auxiliary function mode, and then press the "Increase button" to switch to the <Restore Factory Parameters> interface, as shown below:
 AF- INI
2. Press the "Set key" again to enter the execution mode, as shown below
 ""INI. -""
3. Keep pressing "" "▲ Increase key" until the ready screen appears, as shown in the figure below
  ""INI. -""> ""INI.--""> ""INI. ---""> ""---- -""> ""S T A R T""
4. Keep pressing """◀Left key" until the status of completion or failure of restoring parameters appears, as shown below
  ""S T A R T .""> ""S T A R. T""> ""S T A. R T""> ""S T. A R T""> ""F i n i s h"""

25. A4 servo parameter write and save steps:

Answer: From the LED monitoring state, press the MODE button to switch to the parameter writing mode, the interface is as shown in the figure below: ”EE-SET” After pressing the Set button, press the increase button ▲, until the “F inish” writing step is completed, The operation interface is as follows: ""EEP-”.> ”EEP--”> ”EEP --- ”> ”------” >”F inish”
26. A4 servo occasionally reports ER.21 encoder power failure during operation, the cause of the failure?

Answer: First check whether it is the encoder cable problem. Check whether the encoder connector is loose or the encoder cable is damaged; if there is no problem, you can adjust PA-08 to 15 to improve the anti-interference of the encoder.

B2-CN3 A4-CN3 definition
SIGN 1 SIGN 16 Negative direction
PULSE 2 PULSE 1 Pulse negative
SIGN 3 SIGN 17 Positive direction
PULSE 4 PULSE 2 Pulse positive
Servo enable 5 Servo enable 3 Servo enable
Zero speed signal 11 Zero speed signal 38 Zero speed signal
Analog input signal 16 Analog input signal 42 Analog input signal Input range 0-10v
GNDA 20 GNDA 41 Analog ground
Servo ready 27 Servo ready 7
COM+ 31 COM+ 36 DI input common terminal 24V
COM- 32 COM- 37 DI output common terminal 0V
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