Install Dc-Bus Power Output Wiring; Ground The 8720Mc-Rps Unit - Allen-Bradley 8720MC-RPS065 User Manual

Chapter 5 Connect the 8720MC-RPS Unit
Install DC-bus Power Output
Wiring

Ground the 8720MC-RPS Unit

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The DC-bus output terminals on the main power terminal block (TB1) or the
DC-bus terminal bars of the 8720MC-RPS unit are used for connecting to
load equipment (inverters). Use the recommended wire sizes shown in
Table 14 and Table 15
equipment. Connect terminal P on the main power terminal block (TB1) or
terminal bar P of the 8720MC-RPS unit to the positive (plus) DC-bus
terminal of the load equipment. Connect terminal N on the terminal block
TB1 or the terminal bar N to the negative (minus) DC-bus terminal of the
load equipment.
ATTENTION: When connecting the DC-bus to multiple external loads and
fuses are not provided in the load equipment, you are responsible for
installing fuses to protect the DC-bus from shorting. Failure to observe this
precaution could result in damage to the equipment.
ATTENTION: Terminal P on the 8720MC-RPS unit must be connected to
terminal P on the load (inverter). Likewise, Terminal N on the 8720MC-RPS
unit must be connected to terminal N on the load (inverter). Failure to
observe this precaution could result in damage to the 8720MC-RPS unit and
the connected load equipment.
When multiple drives are connected to the 8720MC-RPS unit, always install
input fuses before each drive to protect the wiring and the drive. Refer to
Circuit Protection Specifications
Connect an equipment ground conductor to the ground terminal of load
equipment, remote control station (if used), input transformer (if used), and
ground terminal of the 8720MC-RPS unit. Run earth conductor to earth
ground after confirming that the conductors are unbroken. Refer to the
recommended wire size for ground terminals in
This system is operated by switching the DC-bus line from + (plus) bus
voltage to – (minus) bus voltage with reference to ground potential for the
8720MC-RPS operation. For this reason, plus and minus voltages are always
added on a circuit if the equipment has a circuit between the bus line of the
equipment to be connected and the ground (earth). Even if no direct circuit
exists between the bus line and the ground, pulse current will flow through the
stray capacity of the equipment by bus voltage switching. When the 8720MC-
RPS unit and the equipment connected to the 8720MC-RPS unit are not
securely grounded, this current will flow through the circuit and may cause
malfunction of them. If ground is not made properly, it can cause a
malfunction in another system on the same line.
Install an insulating transformer to the input line of the 8720MC-RPS if
unbalanced current flows and earth leakage breaker malfunctions due to the
power supply conditions.
Rockwell Automation Publication 8720MC-RM001K-EN-P - September 2018
for wiring between the 8720MC-RPS unit and the load
on page 17 for recommended devices.
Table 14 and Table 15.