User guide

Xenus Plus User Guide Regen Resistor Sizing and Configuration
Copley Controls 127
For mains voltages not listed in the specification table, use the following formula to determine the
energy that can be absorbed by the drive.
W
capacity
= ½ C (V
regen
2
- (1.414 V
mains
)
2
)
Where:
W
capacity
= The energy that can be absorbed by the bus capacitors, in Joules.
C = Bus capacitance in Farads.
V
regen
= Voltage at which the regen circuit turns on, in volts.
V
mains
= Mains voltage applied to the drive, in volts AC.
A.1.7: Calculate Energy to be Dissipated for Each Deceleration
For each deceleration where the energy exceeds the drive’s capacity, use the following formula to
calculate the energy that must be dissipated by the regen resistor:
E
regen
= E
returned
- E
amp
Where:
E
regen
= Energy that must be dissipated in the regen resistor, in Joules.
E
returned
= Energy delivered back to the drive from the motor, in Joules.
E
amp
= Energy that the drive will absorb, in Joules.
A.1.8: Calculate Pulse Power of Each Deceleration that Exceeds Drive
Capacity
For each deceleration where energy must be dissipated by the regen resistor, use the following
formula to calculate the pulse power that will be dissipated by the regen resistor:
P
pulse
= E
regen
/ T
decel
Where:
P
pulse
= Pulse power in Watts.
E
regen
= Energy that must be dissipated in the regen resistor, in Joules.
T
decel
= Time of the deceleration in seconds.
A.1.9: Calculate Resistance Needed to Dissipate the Pulse Power
Using the maximum pulse power from the previous calculation, calculate the resistance value of
the regen resistor required to dissipate the maximum pulse power: For related drive specifications,
see Regen Circuit Output (p. 61).
R = V
regen
2
/ P
pulse max
Where:
R = Resistance in Ohms.
P
pulse max
= The maximum pulse power.
V
regen
= The voltage at which the regen circuit turns on.
Choose a standard value of resistance less than the calculated value. This value must be greater
than the minimum regen resistor value specified in Regen Circuit Output (p. 61).
A.1.10: Calculate Continuous Power to be Dissipated
Use the following formula to calculate the continuous power that must be dissipated by the regen
resistor. Use each deceleration where energy is dissipated by the regen resistor.
P
cont
= ( E
regen 1
+ E
regen 2
+ E
regen
…) / T
cycle
Where:
P
cont
= The continuous power that will be dissipated by the resistor in Watts.
E
regen n
= Energy being dissipated during decelerations, in Joules.
T
cycle
= Total cycle time in seconds.