SOLAR PUMPING Guidelines - Electrical design and installation of solar pumps
7
SUBMERSIBLE PUMP (OR MOTOR-PUMP GROUP) Whatever the type of pump (centrifugal, helical, volumetric, ...), submersible pumps still have the same main components
shown in figure 10:
•
The Motor (AC, DC, ou multi-voltage), always located in the lower part. The motor is always immersed, which is
necessary for its cooling
•
Suction orifice (inlet) equipped with a coarse strainer to filter large impurities in the water
•
The Pump, always located at the top
•
Discharge orifice (outlet) with screw thread to screw in the discharge pipe. The outlet is generally equipped with a
check valve.
•
A short length of cable (50 cm to 1 m) sealed in the motor so that the installer does not have to open the motor to
connect the power cable (and potentially break its sealing)
It is not necessary to give technical specifications for the type of pump (AC or DC, centrifugal or volumetric, ...), leaving the
choice to the supplier to propose the most adapted product for the best price. Only 2 parameters need to be specified on
the request for quotations, because they have a strong influence on the life time of the pump:
•
The constituent materials of the pump: all parts exposed to water must be in stainless steel of AISI304 minimum
quality, in order to be naturally protected against corrosion
•
Type of motor: for maximum durability, care should be taken to choose “brushless” motors, (note this name is
also used in French-speaking countries). The rotor of these motors is fitted with permanent magnets rather than
electromagnets requiring a supply by friction of brushes (coals), that are a source of breakdowns. Brushless motors
therefore have better performance (no friction) and have no internal wearing parts.
FIGURE 10: STANDARD PUMP
Water
Discharge Cable Pump Mo to r Water
Inlet In addition to requesting a pump in stainless steel AISI304 equipped with a brushless motor, it is also necessary to specify
the quality of the water to be pumped in the quotation request. If sample analysis results are available, indicate the operating
conditions:
•
The water temperature
•
The degree of impurity present in the water (Grain size)
•
Any other parameter concerning the water to be pumped, which could influence the operation of the pump: pH if
different from a neutral pH (7), the chemical composition if particular how/low values, ...
