Rockwell Automation Publication 7000-UM202D-EN-P - May 2018 53
Power Component Definition and Maintenance Chapter 2
5. Using a digital multimeter, measure the capacitance across each phase-
to-neutral of capacitors without removing any connections.
If the difference between the highest and the lowest readings is below
15%, then all capacitors are in good condition. If the difference between
the highest and the lowest readings is off by 15% or more, then you
might have a bad capacitor. If more than one capacitor is used in the
circuit, then you would need to isolate each of them and check them
separately to identify which one is defective.
6. Before disconnecting the capacitors, note the location of all the cables
and mark them accordingly.
7. Disconnect power cables from the capacitor terminals on all four
bushings and isolate them from the capacitor (see Replacing Filter
Capacitors on page 51).
8. Repeat step 5 to check each capacitor separately to confirm which is
defective.
Second Method
1. Ensure there is no power to the equipment.
2. Perform visual inspection to ensure there is no oil leak or bulge in any of
the capacitors.
3. Note the location of all the cables and mark them accordingly.
4. Disconnect power cables from the capacitor terminals on all four
bushings and isolate them from the capacitor (see Replacing Filter
Capacitors on page 51).
ATTENTION: Capacitors that appear bulged or are leaking oil indicate
potential problems with the internal elements. DO NOT USE. These units
must be replaced. Failure to do so may lead to personal injury or death,
property damage, or economic loss.
ATTENTION: To prevent electrical shock, disconnect the main power before
working on the drive. Verify that all circuits are voltage-free using a hot stick
or appropriate voltage-measuring device. Failure to do so may result in injury
or death.
ATTENTION: Verify the load is not running due to process. A freewheeling
motor can generate voltage that feeds back to the equipment.
ATTENTION: Capacitors that appear bulged or are leaking oil indicate
potential problems with the internal elements. DO NOT USE. These units must
be replaced. Failure to do so may lead to personal injury or death, property
damage, or economic loss.
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