Mitsubishi Electric MDS-EX-CV Series Specifications And Instruction Manual page 84

MDS-EX-CV/CVH Series Specifications and Instruction Manual
11 Troubleshooting
11.3 Troubleshooting
Power supply option unit error
Alarm No.
74
An alarm was detected in the power backup unit (an option unit for the power supply).
Investigation details
1 Check the LED display on the power backup unit. Check the LED display on the power back-
Power supply: Overvoltage
Alarm No.
L+ and L- bus voltage or the input voltage in main circuit exceeded the allowable value. As the voltage between
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L+ and L- is high immediately after this alarm, another alarm may occur if this alarm is reset in a short time. Wait
more than 5 min before resetting so that the voltage drops.
Investigation details
1 Check if the alarm repeats.
2 Check the power supply's alarm history.
3 Check the power capacity.
4 Measure the voltage across wires.
[1] Is the voltage 380 V or more even when the
motor is accelerating?
5 Measure the power voltage with a synchroscope,
and check whether there is any distortion.
[1] Are there any other devices causing the pow-
er distortion?
6 Check if there is any abnormality in the unit's am-
bient environment.
(Ex. Noise, grounding, etc.)
Power supply: Function setting error
Alarm No.
The rotary switch setting of external emergency stop is not correct, or a wrong external emergency stop signal
76
is input.
Investigation details
1 Check the rotary switch 1 setting.
2 Check the rotary switch 2 setting.
3 Check if there is any abnormality in the unit's am-
bient environment.
Investigation results
up unit to identify what alarm is occurring to
the unit.
Investigation results
The alarm occurs each time the motor de-
celerates.
The alarm occurs occasionally.
Auxiliary regeneration frequency over (E8)
occurs just before the over-voltage occurs.
Others.
The power capacity is insufficient.
The specified power capacity is secured.
The voltage drops to less than 380 V occa-
sionally.
The voltage exceeds to 480 V occasional-
ly.
The difference of the voltage across wires
is 10 V or more.
The difference of the voltage across wires
is less than 10 V.
The power voltage is distorted.
The power voltage waveform is not abnor-
mal.
Take remedies according to the causes of the abnormality in the ambient environment.
Investigation results
When using external emergency stop, the
rotary switch is not set to "4".
Rotary switch is set to other than "0" to "3". Set rotary switch 2 to "0" to "3".
No abnormality is found in particular.
The grounding is incomplete.
65
Remedies
Fix the error occurring to the power backup
unit and remove the alarm.
Refer to MDS-E/EH Series Instruction
Manual (IB-1501229(ENG)) "List of power
backup function alarms".
Remedies
Check the investigation item No. 3.
Check the investigation item No. 2.
Limit the occurrence of the excessive in-
stantaneous regeneration by not deceler-
ating multiple axes at the same time.
Check the investigation item No. 3.
Increase the power capacity.
Check the investigation item No. 4.
Increase the power capacity.
Lower the input voltage.
Improve the power phase balance.
Check the investigation item No. 5.
Improve the source of the distortion.
Install an AC reactor.
Check the investigation item No. 6.
Remedies
Set the rotary switch 1 to "4".
Replace the drive unit.
Take remedies according to the causes of
the abnormality. Additionally ground and
review.
IB-1501700-A