Siemens SINUMERIK 840C Installation Instructions Manual page 1003

12 Functional Descriptions
12.20.8 Configuration help for generator operation and emergency retraction
Example:
6000 µF (see table 16 kW infeed/regenerative feedback module) - 20%
C =
U = 550 Volt (P1634)
Zk
U = 350 Volt (assumed)
min
E = 1/2 * 4800 µF * ((550 V)
This energy is available at load for a time of:
t = E/P *
min max
where
t = backup time in milliseconds [ms]
min
P = power in kilowatts [kW]
max
= degree of efficiency of the drive unit = 0.90
Example:
E = 432 Ws
P = 16 kW (see table for 16 kW infeed/regenerative feedback module)
max
= 0.90
t = 432 Ws/16 kW * 0.9 = 24.3 ms
min
in order to initiate the emergency retraction.
The table below shows a summary of the values for different infeed/regenerative feedback
units. Nominal and minimum capacitances have been taken into account. The maximum
possible capacitance (load limit) consists of the sum of the capacitances of the
infeed/regenerative feedback module and the axis/spindle modules plus additional external
capacitors (provided by the customer). The minimum capacitance shown in the table takes
account of a component tolerance of -20% (worst case).
Infeed/regen-
erative Max. possible
feedback unit capacitance
(power P ) C [µF]
max max
[kW]
16 6000
36 20000
55 20000
80 20000
120 20000
Note:
In configuring the emergency retraction, a total energy must be calculated to find out if it is
possible to eliminate an additional generator axis/spindle (with an appropriately dimensioned
centrifugal mass).
12–228
2 - (350 V) 2 ) = 432 Ws
Energy Energy
content (at content (at
C ) [Ws] C ) [Ws]
max min
540 432
1800 1440
1800 1440
1800 1440
1800 1440
© Siemens AG 1992 All Rights Reserved
09.95
Backup time Backup time
t at P t at P
n max min max
[ms] [ms]
30.38 24.30
45.00 36.00
29.46 23.56
20.25 16.20
13.50 10.80
6FC5197- AA50
SINUMERIK 840C (IA)