Vogt N Series, Service Manual, Page: 20 / 31

20
Start-up
Designation of the Power Cables of
the Three-Phase Lines By Different
Manufacturers
R = L1
S = L2
T = L3
Designation of Cables and Terminals of
Three-Phase Electric Motor Coils by
Different Manufacturers
X
Y
Z 4
5
6 U2
V2
W2 =
=
= =
=
= U1
V1
W1 =
=
= U
V
W 1
2
3 =
=
=
6. 5.2 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. 6 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 rotates with difficulty, the equipment must not be operated until the cause of the problem is located
and solved.
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. 18-c).