36
Start-up
6.6.2
Rotation Management Control
Before final start-up, it is necessary to check the direction of rotation to ensure correct operation of the pump.
Correct direction of rotation
The motor cables are marked with the letters U-V-W, and should be connected to the corresponding U-V-W terminals on
the control panel. Identify and mark the power supply terminals R-S-T, using a cyclic phase detector with a clockwise
rotating indicator, and connect them to the R-S-T terminals on the control panel.
If you do not have a cyclic phase detector, precede as indicated. Connect the power supply cables to the control panel and
to the power supply circuit, just for a moment, and observe in which direction the motor-pump assembly tends to rotate.
The direction of rotation of the motor is correct when the assembly tends to rotate in the direction indicated by the arrow
cast on the pump. If the motor pump tends to rotate in the opposite direction to that indicated by the arrow, reverse the
position of any two power cables and you will obtain the correct direction of rotation.
6.7
Other General Operating Considerations
•
DO NOT throttle the suction of the pump; throttling the suction of a centrifugal pump causes a reduction of the
absolute pressure at the impeller inlet. This is very harmful for the pump, since it causes erosion and premature
destruction of its components, product of the phenomenon called cavitation. Suction throttling is only allowed when
the available NPSH of the installation exceeds by a wide margin the NPSH required by the pump.
•
If the pump is stalled or turns with difficulty, the equipment must not be operated until the cause of the problem is
located and solved.
Designation of the Cables and Terminals of the
Coils of Three-Phase Electric Motors
by Different Manufacturers
U
1
= U = 1
U
2
= X = 4
V
1
= V = 2
V
2
= Y = 5
W
1
= W = 3
W
2
= Z = 6
Designation of the Power Cables of
the Three-Phase Lines By Different
Manufacturers
R = L
1
S = L
2
T = L
3
Start-up
Motors with 6 wires can be started using a Star/Delta splitter only if the supply line voltage is equal to the minimum voltage
shown on the nameplate, between the two values specified by the manufacturer. To make the star-delta connection, in the
motor box, all jumpers are removed, leaving the terminals free. The 6 wires from the board to the motor connect the 6
terminals of the board to the 6 terminals of the motor junction box as follows: U to U, V to V, W to W, Z to Z, X to X, Y to Y.
(see fig. No. 25-c).
Содержание L Series
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