Rockwell Automation Publication 20Y-TG001C-EN-P - April 2017 71
Precharge Component Section Chapter 6
7. Before removal, note the locations of the DC+, DC–, L1, L2, and L3
wires, and then disconnect these wires.
8. Remove the precharge bridge mounting nuts.
9. Remove and appropriately discard the old precharge bridge.
10. Install the new precharge bridge in reverse order of removal. See To r qu e
Specifications on page 36.
Test the Precharge Resistor
To test the precharge resistor, follow these steps.
1. Remove power from the AFE.
See Remove Power from the AFE
on page 37.
2. Open the LCL filter enclosure door.
3. If present, remove the protective barriers.
See Remove AFE Protective Barriers
on page 44.
4. Measure the resistance between the following two points with an
ohmmeter:
• Between the (+) side of the precharge resistor R6.1 and the (+)
terminal on the TB of the precharge circuit.
• Between the (–) side of the precharge resistor R6.2 and the (–)
terminal on the TB of the precharge circuit.
The precharge resistance is approximately 12.5 Ω for each measurement
for an AFE in an IP20 2500 MCC Style enclosure, or 20 Ω for each
measurement for an AFE in an IP21 Rittal enclosure. If the measured
value is not correct, disconnect a resistor wire and remeasure again. If the
measured value is still not correct, replace the precharge resistor.
Replace the Precharge
Resistor Assembly
AFE in IP20 2500 MCC Style Enclosure
To replace the precharge resistor assembly in an IP20 2500 MCC Style
enclosure, follow these steps.
1. Remove power from the AFE.
See Remove Power from the AFE
on page 37.
2. Open the LCL filter enclosure door.
IMPORTANT Verify that the precharge resistor has not been engineered to
another value by the system engineer to accommodate a larger
system capacitance. The engineered value can change the value of
the precharge resistance. See the PowerFlex Active Front End User
Manual, publication 20Y-UM001
, for total DC bus capacitance limits
for the precharging circuit.
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