REXROTH IndraDrive C - Page 267

Rexroth IndraDrive Calculations 15-9
DOK-INDRV*-SYSTEM*****-PR02-EN-P
z*h*g*mW
pot
=
W
pot
: potential energy [Ws]
m: load mass [kg]
g: gravitational acceleration = 9,81 m/s²
h : lowering height [m]
z: number of lowering processes per cycle
Fig. 15-22: Potential energy of non-balances masses
z
rotgpotg
oninstallatiRD
t
WW
P
+
=
,
;
∑∑
≤
devicesBDoninstallatiRD
PP
,,
P
RD,installation
: generated continuous regenerative power [kW]
P
BD,devices
: allowed braking resistor continuous power [kW]
t
z
: cycle time [s]
W
potg
: sum of potential energies [kWs]
W
rotg
: sum of rotary energies [kWs]
Fig. 15-23: Continuous regenerative power
Peak Regenerative Power
Usually, peak regenerative power will occur when an E-Stop signal is
triggered and all axes brake simultaneously.
CAUTION
Risk of damage due to extended braking times
and distances!
⇒ Select the device such that the sum of peak
regenerative powers of all drives does not exceed
braking resistor peak power of the supply unit.
See the respective motor selection documentation for the peak
regenerative powers.
Peak regenerative power can be roughly estimated by the following
equation:
25,1*9550
n*M
P
maxmax
RS
=
∑∑
≤
devicesBSoninstallatiRS
PP
,,
P
RS,installation
: generated peak regenerated power [kW]
P
BS,devices
: allowed braking resistor peak power [kW]
M
max
: maximum drive torque [Nm]
n
max
: maximum NC useful speed [min
-1
]
1,25: constant for motor and controller efficiency
Fig. 15-24: Peak regenerative power