Inspec-
tion cat-
egory
Inspec-
tion item
Inspection point
Inspection
frequency
Inspection method Criteria Meter
Daily
Peri-
odic
1 year
2 years
Motor General There is no ab-
normal vibration
or sound.
Required
Perform acoustic,
sensory and visual
inspection.
No faults
There is no ab-
normal odor.
Required
Check for abnormal
odor due to over-
heating, damage,
etc.
No faults
Isolation
resist-
ance
Perform megger
check
(between motor
terminals and
ground terminal).
Required
Disconnect wires
from the inverter
main circuit terminals
U, V, W and short-
circuit the three-
phase motor wires.
Then, use a megger
to measure the re-
sistance between
each motor wire and
the ground terminal.
5 MΩ min. 500-VDC
class
megger
*1. The capacitor service life is influenced by the ambient temperature.
For inverter replacement guidelines, refer to A-2 Smoothing Capacitor Life Curve on page A-6.
*2.
The life of the cooling fan depends on environmental conditions, such as the ambient temperature and/or
dust. Check the operating conditions in daily inspection.
10-1-5
Megger Test
Before performing a megger test on external circuits, be sure to disconnect all the terminals of the in-
verter and not to apply the test voltage to the inverter. Use a 500 VDC megger for a megger test.
For a megger test on the inverter main circuit, short-circuit the terminals L1/R, L2/S, L3/T, U, V
, W, DB,
P1, P(+) and N(-) with wires, as shown below.
Because the insulation resistance rating of the single inverter unit is 5 MΩ or higher, it is normal if the
resistance is 5 MΩ or higher.
• For the inverter, do not perform a megger test on the control circuit. Perform it only on the main cir-
cuit.
• Use a tester (in a high resistance range) for a power-on test on the control circuit. Do not use a
megger or buzzer.
10 Maintenance and Inspection
10-6
M1 Series Standard Type User's Manual (I669)
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