Mitsubishi Electric MDS-B-SPJ2 Series Specification Manual page 155

(11) Alarm No.
[Details] The main circuit DC bus (PN) voltage exceeded 400V.
Investigation items
1 Check the P and C
wiring between the
spindle drive unit and
the regenerative
resistor.
2 Is the specified power
capacity secured?
3 Using a tester, check
whether the PN bus
voltage is also 170V or
more during motor
acceleration/decelerati
on.
4 Observe the power
voltage waveform with
a synchroscope.
(During
acceleration/decelerati
on also.)
5 Using a tester,
measure the voltage
between wires R-S,
S-T and T-R.
6 Observe the power
voltage waveform with
a synchroscope.
7 Investigate the wiring
and installation
environment.
1) Is the unit correctly
grounded?
2) Is there any device
that produces noise
around the unit?
11. Troubleshooting
33 : OVERVOLTAGE
Investigation results
There was a broken or loose wire.
The wiring is normal.
The power capacity is insufficient.
No particular problem.
The voltage became 170V or less.
The voltage is 170V or more.
1. Waveform distortion.
2. When there is a partial voltage
drop.
3. Other waveform and frequency
error.
No particular problem.
The voltage difference between each
wire is 10V or more.
No particular problem.
Momentary power failures or voltage
drops sometimes occur.
No particular problem.
1) The grounding is incomplete.
2) The alarm occurs easily when a
specific device is operated.
No particular problem.
Replace the cable. Or, carry out
correct wiring.
Investigate item 2, and carry out the
appropriate measures.
Increase the power capacity.
Investigate item 3, and carry out the
appropriate measures.
Increase the power capacity.
Investigate item 4, and carry out the
appropriate measures.
Eliminate the waveform distortion.
1. Increase the power capacity, or
use a larger power cable.
2. Improve other semiconductor
devices that produce waveform
distortion.
(Additionally install an AC
reactor.)
Investigate item 5, and carry out the
appropriate measures.
Improve the power phase balance.
Investigate item 6, and carry out the
appropriate measures.
Reconsider the power equipment.
Investigate item 7, and carry out the
appropriate measures.
Correctly ground the unit.
Execute noise countermeasures for
the device at the left.
Replace the unit.
11 − 11
Remedy