Rockwell Automation 8720MC 8720MC Regenerative Power Supply User Manual - Manual (Page 67)

4-29 Wiring
Installing DC Bus Power
Output Wiring - All RPS
units
ATTENTION: When connecting the DC bus to plural
number of external load equipment, the user is
responsible for installing fuses to protect the DC bus
from shorting, if no fuse is provided in the load
equipment. Failure to observe this precaution could
result in damage to, or destruction of, the equipment
ATTENTION: Exercise extreme caution for polarity
of wiring when wiring DC bus. Failure to observe
this precaution could result in damage to, or
destruction of, the 8720MC-RPS Regenerative Power
Supply and the connected load equipment.
The DC bus output terminals on the main power terminal block
(TB1) or the DC bus terminal bars of the 8720MC-RPS
Regenerative Power Supply are used for connecting to load
equipment such as inverter. Use the recommended wire size shown
in Tables 4.1 to 4.3 for wiring between the 8720MC-RPS
Regenerative Power Supply and the load equipment. Connect the
terminal P on the main power terminal block (TB1) or the terminal
bar P of the 8720MC-RPS Regenerative Power Supply to the
positive (plus) DC bus terminal of the load equipment, and the
terminal N on the terminal block TB1 or the terminal bar N to the
negative (minus) DC bus terminal of the load equipment. Do not
connect the positive (plus) side with the wiring of the negative
(minus) side. Such miswiring will damage the 8720MC-RPS
Regenerative Power Supply and the connected load equipment.
When multiple drives are connected to the 8720MC-RPS
Regenerative Power Supply, always install input fuses before each
drive to protect the wiring and the drive. Select adequate fuse(s)
for the drives.
Connect an adequate equipment grounding conductor to ground
terminal of load equipment, remote control station (if used), input
transformer (if used), and ground terminal of the 8720MC-RPS
Regenerative Power Supply. Run earth conductor to earth ground
after confirming that the conductors are unbroken.
This system is operated by switching DC bus line from + (plus) bus
voltage to - (minus) bus voltage viewing from the ground for the
purpose of controlling. For this reason, plus and minus voltages are
always added on a circuit if equipment has a circuit between the bus
line of equipment to be connected and the ground (earth). Even if
there exists no direct circuit between the bus line and the ground,
pulse current will flow through the stray capacity of the equipment
by bus voltage switching. When 8720MC-RPS and equipment to be
connected to 8720MC-RPS are not securely grounded, this current
will flow through the circuit and may cause malfunction of them. If
grounding is not made properly, it will cause the malfunction of the
other 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.
For grounding, use the wire size of grounding terminal as shown in
Table 4.1 through 4.3.
Grounding the 8720MC-RPS
Regenerative Power Supply
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