Rockwell Automation 7000A PowerFlex Medium Voltage AC Drive (A Frame) - ForGe Control (PanelView 550) - Manual (Page 151)

Component Definition and Maintenance 4-25
7000 “A” Frame 7000A-UM151D-EN-P – March 2013
A T T E N T I O N A T T E N T I O N Verify the load is not running due to process. A
freewheeling motor can generate voltage that
will be back-fed to the equipment being worked
on.
2. Follow appropriate safety steps to isolate the equipment from medium
voltage.
3. Verify that there is no voltage present on the capacitor by using a hot
stick or any other appropriate voltage-measuring device.
4. Perform visual inspection to ensure there is no oil leak or bulge in any
of the capacitors.
5. Note the location of all the cables and mark them accordingly.
6. Disconnect power cables from the capacitor terminals on all four
bushings and isolate them from the capacitor. (Refer to “Filter
Capacitor Replacement” guidelines in the Classic User Manual -
Component Definition and Maintenance chapter (chapter 6) for using
proper torque when reconnecting the capacitors)
7. 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.
A T T E N T I O N A T T E N T I O N The capacitor will charge during this test so care
must be taken to prevent a shock or injury.
When moving the test connections from one
phase to the next, wait for at least five minutes
until the capacitor is discharged. Using a hot
stock or other voltage-measuring device, verify
that the capacitor is fully discharged before
touching it.
8. Now, 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 then the
capacitor must be replaced.
Example: An example is given below to illustrate how the capacitance
value is calculated.