User guide

Xenus Plus User Guide Operational Theory
Copley Controls 57
2.17: Regen Resistor Theory
2.17.1: Regeneration
When a load is accelerated, electrical energy is converted into mechanical energy. During
deceleration the conversion is reversed. This is called regeneration. Some of this regenerated
energy is lost to friction in the mechanical system. More of this energy is converted to heat due to
I2R losses in the motor windings, cabling, and drive electronics. The remainder of the energy is
added to the electrical energy already stored in the internal capacitor bank of the drive. The result
of this energy being added is an increase in the voltage on the capacitor bank.
2.17.2: Regen Resistor
If too much energy is added to the capacitor bank, the voltage rises to a point where the drive's
over voltage protection shuts down the drive. To prevent this, a regen circuit shunts some of the
energy into an external regen resistor when the voltage rises too high.
2.17.3: Regen Circuit Components
The drive provides an internal transistor that is used in combination with an external resistor.
Copley Controls supplies compatible resistors as described in Regen Resistor Assemblies (p.
155). When using a resistor acquired from another source, be sure it meets the specifications
described in Regen Resistor Sizing and Specification (p. 124).
2.17.4: Regen Circuit Protections
The drive protects the regen circuit against short circuit, and uses I
2
T peak current/time algorithms
to protect both the external resistor and the internal transistor.
2.17.5: Configurable Custom Resistor
The following values can be entered for a custom resistor using CME 2:
Option
Description
Resistance Value
Value in Ohms of the resistor
Continuous Power
Continuous power rating of the resistor
Peak Power
Peak power rating of the resistor
Time at Peak Power
Time at peak power of resistor
For more information, see Regen Resistor Sizing and Specification (p. 124).