12 Functional Descriptions 09.95
12.20.8 Configuration help for generator operation and emergency retraction
Example:
C = 6000 µF (see table 16 kW infeed/regenerative feedback module) - 20%
U
Zk
= 550 Volt (P1634)
U
min
= 350 Volt (assumed)
E = 1/2 * 4800 µF * ((550 V)
2
- (350 V)
2
) = 432 Ws
This energy is available at load for a time of:
t
min
=E/P
max
*
where
t
min
= backup time in milliseconds [ms]
P
max
= power in kilowatts [kW]
= degree of efficiency of the drive unit = 0.90
Example:
E = 432 Ws
P
max
= 16 kW (see table for 16 kW infeed/regenerative feedback module)
= 0.90
t
min
= 432 Ws/16 kW * 0.9 = 24.3 ms
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
feedback unit
(power P
max
)
[kW]
Max. possible
capacitance
C
max
[µF]
Energy
content (at
C
max
) [Ws]
Energy
content (at
C
min
) [Ws]
Backup time
t
n
at P
max
[ms]
Backup time
t
min
at P
max
[ms]
16 6000 540 432 30.38 24.30
36 20000 1800 1440 45.00 36.00
55 20000 1800 1440 29.46 23.56
80 20000 1800 1440 20.25 16.20
120 20000 1800 1440 13.50 10.80
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
© Siemens AG 1992 All Rights Reserved 6FC5197- AA50
SINUMERIK 840C (IA)
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