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unusually noisy
Motor bearings worn
Foreign matter between fixed
and rotating parts
Pump operation
affected by cavitation
EN
14.6 WHEN THE SWITCH CLOSES, THE PUMP DOES NOT MANAGE TO
COMPLETE EVEN ONE TURN OR STRUGGLES TO TURN THE ODD
HALF TURN BEFORE THE CIRCUIT BREAKER TRIPS OR FUSES
BLOW
Motor short-circuited
Short-circuit due to incorrect
connection
14.7 RESIDUAL CURRENT CIRCUIT BREAKER TRIPS AS SOON AS
SWITCH CLOSES
Leakage current owing to
damaged insulation of motor,
cables or other electric
components
14.8 PUMP PERFORMS A FEW TURNS IN OPPOSITE DIRECTION WHEN
STOPPING
Foot valve leaking
Suction pipe leaking
15. SUPPLIED TECHNICAL DOCUMENTATION
15.1 STANDARD VOLTAGES SHOWN ON THE PLATE WITH THEIR
RESPECTIVE TOLERANCES
Frequency
[kW]
[Hz]
0.37 ÷ 4.0
50
≥ 5.5
15.2 MOTOR OUTPUT REDUCTION FACTORS
When the motor-driven pump is installed in a site where the ambient temperature
is higher than 40°C and/or its altitude is over 1000 m above sea level, the motor's
output decreases.
The table attached features the reduction factors based on temperature and
altitude. To prevent overheating, you must replace the motor with a different
18
Replace bearings
- Disassemble and clean pump
- Call our nearest Servicing Department to
do the job
Reduce flow rate by throttling delivery line. If
cavitation persists, check:
- Suction height
- Pressure loss along suction line (diameter
of pipe, elbows etc.)
- Liquid temperature
- Delivery line backpressure
- Check and replace
- Call an electrician specialized
- Check and reconnect correctly
- Call an electrician specialized
- Check and replace electric component with
ground fault
- Call an electrician specialized
- Condensate build-up in the motor
- Presence of foreign bodies
Check, clean or replace
Check and repair
Phase
UN [V] ± %
[~]
3 ~
230 Δ / 400 Y ± 10%
3 ~
400 Δ / 690 Y ± 10%
version whose rated output multiplied by the factor corresponding to the
temperature and altitude is greater than or equal to that of the standard motor.
The standard motor can only be used if the relevant application can accept a
reduction in flow rate, achieved by throttling the delivery line so as to reduce the
current absorbed by an amount equal to the correction factor.
T(°C)
1000
1500
40
1
0.96
45
0.95
0.92
50
0.92
0.90
55
0.88
0.85
60
0.83
0.82
65
0.79
0.76
15.3 MAXIMUM WORKING PRESSURE CHART
Pressure indicated according to the number of impellers.
50 Hz
Pmax
EVMSN3
EVMSN5
1.6
3 ÷ 18
3 ÷ 15
2.5
20 ÷ 33
16 ÷ 27
15.4 CAVITATION
Cavitation, as you may know, is a destructive problem for pumps, a phenomenon
that is encountered when the water drawn in is transformed into steam inside the
pump. EVMSN pumps, fitted with internal hydraulic parts made from stainless
steel, suffer less than other pumps built with materials of poorer quality, though
they are not entirely immune to the damage that cavitation brings.
Hence pumps must be installed in compliance with the laws of physics and with
rules relating to fluids as well as to the actual pumps.
Below we give you just the practical results of the above-mentioned rules and
laws of physics.
Under standard environmental conditions (15°C, at sea level), water turns into
steam when subjected to a negative pressure greater than 10.33 m. Hence 10.33
m is the water's maximum theoretical suction height. EVMSN pumps, like all
centrifugal pumps, cannot exploit theoretical suction height to the full owing to their
internal loss, known as NPSHr, which has to be deducted. Hence the theoretical
suction lift of each EVMSN pump is 10.33 m less its NPSHr at the work point in
question.
The NPSHr can be determined by consulting the standard curves featured in the
brochures and must be taken into consideration when first selecting the pump.
When the pump is part of a flooded installation or has to draw cold water from 1
or 2 m with a short pipe with one or more wide bends, NPSHr can be disregarded.
Consequently, the more difficult the installation, the more the NPSHr value has to
be taken into consideration. Installation becomes difficult when:
a) Suction height is high;
b) Suction line is long and/or has lots of bends and/or has several valves (high
pressure losses along suction line);
c) Foot valve has high flow resistance (high pressure losses along suction line);
d) Pump is used with a flow rate close to the maximum rated flow rate (NPSHr
increases as flow rate increases over the rate where efficiency is highest);
e) Water temperature is high. (It is likely you will have to install the pump with a
flooded arrangement where values approach 80-85°C);
f) Altitude is high (in the mountains).
Altitude (m.a.s.l.)
2000
2500
0.94
0.90
0.90
0.88
0.87
0.85
0.83
0.81
0.80
0.77
0.74
0.72
EVMSN10
2 ÷ 14
16 ÷ 20
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