CHAPTER 7 MAINTENANCE AND INSPECTION

3. Overvoltage

[Display]

Hu

[Description of detected alarm]

The DC voltage inside the servo amplifier exceeds the upper limit.

[Cause and remedy]

Cause

Remedy

The source voltage is too high

(immediately after power-on).

 Check if the source voltage is within the specification

limits.

 Insert a reactor if there is a power factor improvement

capacitor.

Unconnected external regenerative  Connect the external regenerative resistor.

resistor or wrong wiring

 Correct the wiring of the external regenerative resistor.

Broken regenerative transistor

Replace the servo amplifier.

The internal DC voltage can be checked in the monitor mode of the keypad.

[on15]: Internal DC link voltage (max. value)

Approximately over 420 V, overvoltage is detected.

4. Encoder Trouble

[Display]

[Description of detected alarm]

7

Et1

Et2

There is a fault in the encoder built in the servomotor.

(Communications are normal.)

 Et1: Single revolution position detection fault of encoder

 Et2: Encoder memory data reading fault

[Cause and remedy]

Cause

Fault in data sent from encoder

Failure of encoder

Remedy

Use shielded cables to eliminate noise effects.

Replace the servomotor.

5. Circuit Trouble

[Display]

ct

[Description of detected alarm]

There is a fault in the source control power voltage inside the

servo amplifier. There may be a failure in the internal circuit.

[Cause and remedy]

Cause

Failure of servo amplifier

Remedy

Turn the power off then on again. If restoration

is not obtained, replace the servo amplifier.

Troubleshooting Method 7-7