Seite
5
von
10
only suited for one direction of rotation, it is indicated with an arrow on the motor
fan cowl.
Connecting cables must comply with the IEC regulations. Line fuses only protect the
cables in case of short
–
circuiting and do not constitute a safeguard against the
overheating of the winding caused by overload. Therefore it is recommended that a
motor start- and overload protection is mounted, giving single phase and overload
protection.
5.2
Circuit details
Normally our motors are provided with a terminal box with six connections, to which
six leads from the winding are connected either in a delta connection or in a star
connection by means of connection links. Usually two voltages are indicated on the
rating
–
plate of these motors, which mean that the motor can be connected to a
circuit having one of these voltages.
If the mains voltage is corresponding with the lowest indicated voltage, the winding
has to be connected in delta connection (see
figure 1
); if it is corresponding with the
highest indicated voltage, the winding has to be connected in star connection (see
figure 2
). A motor with e.g. 230/400V on its rating
–
plate is suited to be switched on
directly, on a circuit with a voltage of 230 V between phases with the winding
connected in a delta connection, or on a circuit with a voltage of 400 V with the
winding connected in a star connection.
V2
U2
W2
W1
V1
U1
Δ
- Connection
lo
w
v
o
lt
a
g
e
L1
L2
L3
Abb. 1:
Delta connection
V2
U2
W2
W1
V1
U1
Y
- Connection
h
ig
h
v
o
lt
a
g
e
L1
L2
L3
Abb. 2:
Star connection
If the motor is switched on with a star
–
delta starter the motor is only suited for a
main voltage on the rating-plate, this is the delta voltage. In this case, the connection
strips on the terminal box have to be removed when the motor is connected. The
star/delta connection will be made successively during the start up.
