Rockwell Automation SA3100 Diag,Troublesht,Startup,Guide - Manual (Page 37)

Installation and Start-Up Guidelines 4-5
Step 2. Turn off and lock out all incoming power.
Step 3. Wait five minutes to allow the DC bus voltage to dissipate.
Step 4. Measure the DC bus potential with a voltmeter before working on the unit.
Measure the voltage across the DC + and DC - terminals on terminal block
TB1. See Appendix I for terminal block identification. When the DC bus
potential is down to less than 5 volts, touch a 50 ohm, 50 W or larger resistor
across the DC bus terminals for twenty seconds to allow any remaining
voltage to dissipate.
Remove the resistor and re-measure the DC bus potential. It should now
be 0V.
Step 5. Verify the following:
a. All connections are in strict conformance to the wiring diagrams.
b. There are no loose or broken connections.
c. There are no damaged components.
Step 6. Repeat the original test that failed.
4.7.2 Recommended Test Equipment
Rockwell recommends the following test equipment:
• Isolated oscilloscope with a current probe and x100 probe for DC bus
measurements. An isolation transformer is needed to isolate the oscilloscope and
any other equipment.
• AC and DC clamp-on ammeters
• Multimeter having a sensitivity of 20K
Ω
/volt
• Chart recorder
• Isolated voltmeter
• 50 ohm, 50W resistor for discharging bus capacitors
A megohmmeter (megger) may be used to reliably verify the absence of inadvertent
grounding of the motor. Failure to follow proper procedure when using a megger may
cause damage to the drive.
!
ATTENTION:DC bus capacitors retain hazardous voltages after input
power has been disconnected. After disconnecting input power, wait five
(5) minutes for the DC bus capacitors to discharge. Then check the
voltage across the DC bus test points to ensure the bus capacitors are
discharged before touching any internal components. Failure to observe
this precaution could result in severe bodily injury or loss of life.
!
ATTENTION:If a megohmmeter is used, disconnect all leads between
the rotating equipment and the drive cabinet. This will prevent damage
to electronic circuitry (Power Modules and their associated circuits, etc.)
due to the high voltage generated by the megger. Failure to observe this
precaution could result in damage to, or destruction of, the equipment.