Rockwell Automation 1391ES AC Servo Controller - Manual (Page 61)

Transformers and Shunt Regulators
Chapter 9
9-59
Frequent overvoltage trips on high inertia systems (load is 2 or 3 times the
motor inertia) during regenerative states (deceleration) may be an
indication that an external shunt resistor having increased power
dissipation capacity is required. Based on the data supplied, Allen-Bradley
will specify a shunt resistor with the proper resistance value for the
controller being used.
Shunt Regulator Installation External Shunt Resistors
The 1391B-ES is designed to allow the use of an external shunt resistor on
the 22.5 and 45A units. To use an external shunt resistor with the 22.5A
units, the user must reconfigure the controller at terminal block TB5.
The following steps provide the information needed to properly convert
22.5A controllers for use with an external shunt resistor and fuse. Refer to
the resistor and fuse mounting dimensions provided in Appendix A and the
Interconnect Diagram in Appendix B, as required.
ATTENTION: To guard against an electrical shock hazard,
ensure that all power to the controller has been removed prior to
performing the following procedure and the bus voltage at
terminal 9 (+) and 7 (–) of TB5 measures 0.00 volts.
!
24. Remove and discard the jumper present between terminals 8 and 10 of
TB5. This disconnects the internal shunt resistor and fuse from the
shunt regulator circuit.
ATTENTION: When using an external shunt resistor assembly
with the 22.5A 1391B-ES, ensure that the internal resistor
assembly has been disconnected per the above instructions.
Personal injury and/or equipment damage could result from an
overheated resistor if the internal resistor is not disconnected.
!
25. Connect one end of the new external shunt fuse to terminal 9 of TB5.
Connect the other end of the fuse to one end of the shunt resistor.
Important: The external shunt resistor must have a fuse in series with
the shunt resistor. Refer to the paragraph entitled “Shunt Fusing” for
more information.
26. Connect the remaining end of the shunt resistor to terminal 8 of TB5.
27. Using Table 9.B, set the Duty Cycle Selector Switch to the appropriate
setting for the resistor being used.
28. Install the appropriate shunt fuse in its holder.