Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive (A Frame) - ForGe Control User Manual
Page 101
Rockwell Automation Publication 7000A-UM200C-EN-P - June 2014
101
Component Definition and Maintenance
Chapter 3
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
5.
Connect a low voltage single-phase test power, for instance 110V or 220V,
across a phase and the neutral of the capacitor. Switch on the test power
and measure the test voltage and current drawn by the capacitor. Repeat
the test for all three phases and note down the test voltage and current.
6.
Calculate the capacitance from the measured values of test voltage and
current. For a good capacitor, the calculated capacitance value for each of
the three readings should be within ±15% of the capacitor nameplate
micro-Farad. If it is outside this range, the capacitor must be replaced.
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.
ATTENTION: The capacitor will charge during this test so take care to prevent a
shock or injury. When moving the test connections from one phase to the next,
wait five minutes minimum for the capacitor to discharge.