SIRIUS 3RA28 function modules for mounting on 3RT2 contactors
7.4 Functions
SIRIUS Innovations
System Manual, 01/2011, A8E56203870002-03
655
7.4.2.4 Star-delta (wye-delta) function
Contacts
The function module (comprising basic module with integrated control logic and 2 coupling
modules) has 2 internal NO contacts.
Time ranges
The start time in star operation can be set between 0.5 and 60 s. The changeover delay is
set to a non-adjustable value of 50 ms.
Function chart
3RA2816-0EW20
VV PV
<4
˂4
4
Method of operation
The function module for star-delta (wye-delta) start is responsible for the electrical interlock
and the timing relay function (dead interval from star (wye) operation to delta operation).
Control is exclusively via A1/A2 on the line contactor below. Additional wiring is therefore not
required. The supply voltage is routed via a ribbon cable, eliminating the need for control
circuit wiring.
The instantaneous star contact and the time-delayed delta contact share the same contact
root.
To avoid inter-phase short circuits, the changeover delay from star (wye) to delta is 50 ms.
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