Parker Aries AR-04CE - Energy Absorbed by Drive Capacitors

Parker Hannifin
- 96 – Aries Controller Hardware Installation Guide
mghEp
=
Where
E
p
= potential energy (Joules)
m = mass of forcer and load (kg)
g = gravitational constant (9.81 m/s
2
)
h = vertical height change during deceleration (m)
Energy Absorbed by Drive Capacitors
The Aries Controller drive capacitors absorb some of the kinetic and potential
energy. While the capacitors absorb energy, the bus voltage increases.
Later, the capacitors release that potential energy in subsequent
accelerations, or into typical drive losses.
If too much energy is absorbed by the capacitors, the drive/controller faults
from over-voltage. Under these circumstances, an external power dump
resistor is required.
That ability to absorb energy can be defined in terms of capacitance and
voltage.
)(
2
1
22
NOMTRIPC
VVCE −=
Where
E
C
= energy that can be absorbed by the drive capacitors (Joules)
C = drive capacitance (Farads)
V
TRIP
= power dump trip DC voltage (400 VDC)
V
NOM
= nominal DC motor voltage (typically AC mains voltage at
2
; for
example, 120 VAC *
2
= 170 VDC)
Fortunately, for a given drive the capacitance and voltages are fixed. The
table below provides the necessary information and results from the above
calculation.
Drive Capacitance
(uF)
V
TRIP
(VDC)
E
C
(120 VAC)
Joules
E
C
(240 VAC)
Joules
AR-04CE 880 400 57 19
AR-08CE 1100 400 72 24
AR-13CE 1590 400 104 35
Note: When the voltage drops below 385 VDC, the drive stops dissipating power through the
power dump resistor.