Parker Hannifin
Appendix B External Power-Dump Resistor Selection 175
External Power-Dump Resistor Selection Deceleration generates excess kinetic and potential energy. You can remove
the energy through regeneration—a process where the motor acts as
generator. Regeneration allows you to transfer the excess energy from the
motor and load back to the power supply.
When the drive and assorted losses cannot remove all the stored kinetic
energy, you must connect an external power-dump resistor. Connecting an
external power-dump resistor to the Aries drive helps dissipate the excess
kinetic and potential energy.
While the Aries drive contains circuitry to control an external power dump
resistor, resistor selection depends on the requirements of your particular
application.
There are two methods for selecting the appropriate external power-dump
resistor:
• “Simplified Resistor Selection” provides quick recommendations for
Parker drive and motor combinations.
• “Calculating Resistance—Rotary Motors” steps you through the
relevant formulas to determine the needs of your particular
application.
Note: Both methods assume regeneration occurs during a trapezoidal move.
Important — It is possible to overload an Aries drive or the combination of
an Aries drive and power dump resistor.
If at the end of the calculations you find the required resistor is less than
allowed for your specific Aries model, or requires a watt rating greater than
the rated resistors available, do not use the Aries drive in your application.
Aries drive models AR-01xx, AR-02xx, AR-04xx, AR-08xx, and AR-13xx,
require external resistance values of 22 Ohms or greater.
Aries drive models AR-20xE and AR-30xErequire external resistance values
of 8 Ohms or greater
Many applications do not require a power-dump resistor because the drive
can absorb or dissipate the regenerative deceleration energy. However, if a
drive faults from over-voltage during a deceleration event, an external power
dump resistor is probably required.
Table 57 contains recommended power-dump resistors for specific Aries
drive and Parker Hannifin motor combinations. The recommendations are
based on the calculations presented in the section titled “Calculating
Resistance—Rotary Motors”. These recommendations assume a worst-case
load-to-rotor inertia ratio of 10 to 1, maximum duty cycle and maximum
deceleration from maximum velocity for that specific motor/drive pairing.
These are recommendations only—while not optimized for your particular
application, they will work in most situations.