Rockwell Automation 20G PowerFlex SCR Bus Supply - Manual (Page 28)

1-14 Installation/Wiring
PowerFlex SCR Bus Supply User Manual
Publication 20S-UM001G-EN-P
Disconnecting MOVs The PowerFlex SCR Bus Supply contains protective MOVs that are
referenced to ground. To prevent damage, the MOVs should be
disconnected from ground if the Bus Supply is installed on any
non-solid grounded distribution system where the line-to-ground voltages
on any phase could exceed 125% of the nominal line-to-line voltage. To
disconnect the MOVs from ground, remove the jumper (12-GND) on the
control terminal block shown in
Figure 1.7 on page 1-11 . Solid and
non-solid grounded systems are defined in Table 1.G .
Table 1.G Recommended MOV Configurations
For more information on non-solid grounded system installation, see Wiring
and Grounding Guidelines for Pulse Width Modulated (PWM) AC Drives
(publication DRIVES-UM001).
Table 1.H Jumper Removal
Power Source Type
(1)
(1)
It is highly recommended to accurately determine the power source type and then configure appropriately.
MOV/Input Filter
Capacitors
(2)
(2) When MOVs are disconnected, the power system must have its own transient protection to ensure known and
controlled voltages.
Benefits of Correct Power Source
Type Configuration
Solid Grounded
• AC fed, solidly grounded
• DC fed from passive rectifier which
has an AC source and solid ground
Connected • UL compliance
• Reduced electrical noise
• Most stable operation
• EMC compliance
• Reduced voltage stress on
components and motor bearings
Non-Solid Grounded
• AC fed ungrounded
• Impedance grounded
• High resistive ground
• B phase ground
• Regenerative unit (common DC bus
supply and brake)
• DC fed from an active converter
Disconnected • Helps avoid severe equipment
damage when ground fault occurs
!
ATTENTION: To avoid an electric shock hazard, verify that the
voltage on the bus capacitors has discharged before removing the
jumper. Measure the DC bus voltage at the +DC and –DC output
terminals. The voltage must be zero.
Item Jumper Jumper Location Removes…
➍
12 and GND Control Terminals
(1)
(1) For control terminal location, see Figure 1.4 , Figure 1.5 or Figure 1.6 .
MOVs from Ground