User guide

Regen Resistor Sizing and Configuration Xenus XTL User Guide
140 Copley Controls Corp.
A.1.6: Determine if Energy Returned Exceeds Amplifier Capacity
Compare the amount of energy returned to the amplifier in each deceleration with the amplifier's
energy absorption capacity. For related amplifier specifications, see Regen Circuit Output (p. 37).
For mains voltages not listed in the specification table, use the following formula to determine the
energy that can be absorbed by the amplifier.
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
r
egen
= Voltage at which the regen circuit turns on, in volts.
V
mains
= Mains voltage applied to the amplifier, in volts AC.
A.1.7: Calculate Energy to be Dissipated for Each Deceleration
For each deceleration where the energy exceeds the amplifier’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
r
eturned
= Energy delivered back to the amplifier from the motor, in joules.
E
amp
= Energy that the amplifier will absorb, in joules.
A.1.8: Calculate Pulse Power of Each Deceleration that Exceeds Amplifier
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 amplifier
specifications, see Regen Circuit Output (p. 37).
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. 37).