Electrical Connection - DAB KV 3 Serie Instrucciones Para La Instalación Y El Mantenimiento

phenomena which occur when, at the impeller intake, the absolute pressure falls to values that allow the formation of vapour bubbles in
the fluid, so that the pump works irregularly with a fall in head. The pump must not cavitate because, as well as producing considerable
noise similar to metallic hammering, it would cause irreparable damage to the impeller.
To determine the suction level Z1, the following formula must be applied:
dove:
Z1 = difference in level in metres between the intake mouth of the pump and the free surface of the liquid to be pumped.
Pb = barometric pressure in mcw of the place of installation.(Fig.3, pag. 76)
NPSH = net load at intake of the place of work (Fig. 5-6 page 77-78)
Hr = load loss in metres on the whole intake duct (pipe - curves - foot valves)
pV = vapour tension in metres of the liquid in relation to the temperature expressed in °C (Fig.4, pag.76)
Example 1: installation at sea level and fluid at t = 20°C
Required N.P.S.H.: 3,25 m
pb : 10,33 mca (Fig.3, pag. 76)
Hr: 2,04 m
t: 20°C
pV: 0.22 m (Fig.4, pag. 76)
Z1: 10,33 – 3,25 – 2,04 – 0,22 = 4,82 approx.
Example 2: installation at a height of 1500 m and fluid at t = 50°C
required N.P.S.H. : 3,25 m
pb : 8,6 mca (Fig.3, pag. 76)
Hr: 2,04 m
t: 50°C
pV: 1,147 m (Fig.4, pag. 76)
Z1: 8,6 – 3,25 – 2,04 – 1,147 = 2,16 approx.
Example 3: installation at sea level and fluid at t = 90°C
required N.P.S.H.: 3,25 m
pb : 10,33 mca (Fig.3, pag. 76)
Hr: 2,04 m
t: 90°C
pV: 7,035 m (Fig.4, pag. 76)
Z1: 10,33 – 3,25 – 2,04 – 7,035 = -1,99 approx.
In the last case, in order to operate correctly the pump must be fed with a positive head of 1.99 - 2 m, that is the free surface of the water must be
2 m higher than the axis of the pump intake aperture.
N.B.: it is always good practice to leave a safety margin (0.5 m in the case of cold water) to allow for errors or unexpected
variations in the estimated data. This margin becomes especially important with liquids at a temperature close to boiling
point, because slight temperature variations cause considerable differences in the working conditions. For example in the
third case, if instead of 90°C the water temperature reaches 95°C at any time, the head required by the pump would no longer
be 1.99 but 3.51 metres.
8.

ELECTRICAL CONNECTION

Scrupulously follow the wiring diagrams inside the terminal board box and those on page 2 of this manual.
The requirements of the electric energy supply company must be scrupulously complied with. In the case of three-phase
motors with star-delta start, ensure that the switch-over time from star to delta is as short as possible and that it falls within table 8.1 on page 74.
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Before opening the terminal board and working on the pump, ensure that the power has been switched off.
Check the mains voltage before making any connection. If it is the same as the voltage on the data plate, proceed to connect the wires
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to the terminal board, giving priority to the earth lead. (Fig.E, pag.1)
The pumps must always be connected to an external switch.
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Three-phase motors must be protected with special remote-control motor-protectors calibrated for the current shown on the plate.
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The terminal board may be arranged in four different positions, turning the motor through 90°. If necessary, proceed as follows:
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KV 3/_ - KV 6/_ - KV 10/_ : remove the fan cover, releasing it from the groove in the motor end cover. Remove the fan from the rotor shaft
by prising it off with two screwdrivers or levers, levering on the cover. Unscrew the tie bolts from the motor end cover and the discharge body.
Remove the cover and retain the thrust bearing. Turn the stator into the desired position. Fit the thrust bearing onto the bearing and place
the motor cover on top. Tighten the four tie bolts and check that the shaft is turning freely. If not, slacken the tie bolts and tap a few times
with a plastic hammer. Tighten the tie bolts again and check that the shaft is turning freely. Fit the fan onto the knurled end of the rotor shaft,
tapping lightly with the hammer, and fit the fan cover onto the motor end cover.
KV 32/_ - KV 40/_ - KV 50/_ : loosen the four bolts joining the motor flange and the support. Turn the motor into the desired position and
replace the screws.
ENGLISH
Z1 = pb - rqd. N.P.S.H. - Hr - correct pV
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