Safety Guidelines; Star-Delta Starter" Control Function - Siemens SIMOCODE pro System Manual

Motor control
4.2.7

"Star-delta starter" control function

Description
Star-delta starting is used to limit the starting current and to avoid
overloading the network. In this control function, SIMOCODE pro initially
starts the motor with a star-switched stator winding and then switches it to
delta.
Control commands
• Start with "ON" first activates the QE1 contactor control (star contactor) and
then immediately activates the QE3 contactor control (network contactor)
• Stop with "OFF" deactivates the QE1, QE2 and QE3 contactor controls.
The control commands can be issued to SIMOCODE pro from arbitrary
control stations (see also the description of "control stations"). Thus, the
inputs (plugs) must be connected to the corresponding sockets, preferably
to the "Enabled control command" sockets. Every fault message causes the
QE1, QE2 and QE3 contactor controls to be deactivated.
Switching from star to delta
For this, SIMOCODE pro first deactivates the QE1 contactor control before
connecting the QE2 contactor control (delta contactor).
SIMOCODE pro switches from star to delta:
• Current-dependent, for decreasing current below the following thresholds:
- Transformer installed in delta circuit: I < 150 % I
- Transformer installed in supply line: I < 90 % I
• Time-dependent to the time set in the parameter "Maximum star time" when
the current in the star operation does not sink below this threshold.

Safety guidelines

Notice
It is recommended to wire the QE contactor controls to the relay outputs of
the basic unit.
Notice
If you use internal earth-fault detection for star-delta circuits, this can lead to
false trippings. During delta operation, the summation current is non-zero
due to harmonics.
4-30
s
s
SIMOCODE pro
GWA 4NEB 631 6050-22 DS 03