Installation
15
The three-phase cur-
rent motor circuit
The direction of rotation must be checked on pumps with three-phase motors!
The connections U1 - L2, V1 - L1 and W1 - L3 result in a clockwise rotation of the motor
shaft as seen looking towards the motor fan.
Delta Connection
The three coils are connected in series with the connection point connected to the mains.
The voltage of each coil is the same as the mains voltage whereas the mains current is
the cube root of the coil current. Delta connections are denoted by the symbol
∆
. The
voltage between the mains supply lines is called mains voltage. The mains current is the
current which flows in the supply lines.
Fig. 6:
Motor coil and connecting plate of Delta Connection (for low voltage)
Star Connection
The ends of the three coils are connected at the star center. The terminal voltage is the
cube root of the coil voltage; the mains and the coil current are the same. Star connec-
tions are denoted by the symbol
Y
.
DANGER
Voltage-bearing elements
Danger to life from electric shock.
The electrical connection can be carried out only by trained and authorised electri-
cians.
Disconnect the power supply and secure it against being switched back on.
Ensure the system is adequately earthed.
NOTICE
Excess voltage!
Danger of destroying the motor.
Power connections must comply with local regulations. Voltage and frequency infor-
mation given on the motor rating plate must correspond to the mains voltage and fre-
quency values.
To protect the motor and supply cable in case of malfunction, mains fuse protection
must be implemented. Recommended: Type K slow blow circuit breaker.
NOTICE
Thermal motor overload!
Inadequate cooling at low motor speeds.
When operating the pump with frequency converter, follow the rotation speed range,
specified in the technical data.
W2
U1
L1
V2
V1
W1
U2
L3
L2
W2 U2 V2
U1 V1
W1
L1
L2
L3
