Accessories Installation
BUG 3/2/20 Basic Feed Unit 29
Baumüller Nürnberg GmbH 5.96064.02
5.5 Accessories
5.5.1 Transformers
You connect servo drives to the mains by using a three-phase current transformer. Calculate
the power from the absorbed power, P
M
, of the individual motors added to the power losses of
the servo units. When rating the transformer, you must take into account a form factor of 1.2
due to the harmonics.
P
PPP P
G
MM M M
=
+++
123 4
M
N
: Rated torque in Nm
n
N
: Rated speed in RPM
P: Power in kW
η: Efficiency of motor
P
Bus
: Losses of the servo power unit
P
Mn
P
M
NN
Bus
=+05
9550
.*
*
* η
G = 1 (for 1 axis)
G = 1.15 (for 2 axes)
G = 1.32 (for 3 axes)
G = 1.75 (for 4 axes)
P
M
represents an average mean value (
n
n
max
.= 05) matched to a typical CNC feed drive.
When operating at rated speed (
n
n
max
= 1), you must take into account the complete motor
power.
Isolating transformer or autotransformer
Autotransformers are preferable at power ratings above 5 kVA. Note that the intermediate
circuit may not be grounded and that potential is connected to the intermediate circuit as well
as the motor. If necessary, you may need to limit the peak starting current. These recommen-
dations apply to Baumüller transformers only!
Technical Data of Transformers
Isolating transformer
*)
Autotransformer
Rated Input Voltage
400 V/3 ~
50/60 Hz
400 V/3 ~
50/60 Hz
Rated Output Voltage 230 V/3 ~ 230 V/3 ~
Switching Group YNy0 Yn0
Mode S1 at 40° C S1 at 40° C
Type of Protection IP 00, Insulation class E IP 00, Insulation class E
Ambient Temperature +40° C max. +40° C max.
*)
Do not connect the star point to the mains
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