• Are there any particular instructions for ATEX version electric pumps (explosion proof)?
    1. Do not work on cable glands or open the motor casing; these works are reserved to Caprari authorised workshops.
    2. The operating characteristics of these machines must comply with the characteristics specified in the nameplate and in the attached EX certificate.
    3. Minimum head is at the top of the electric motor for S1 machines and on pump casing for electric pumps intended for intermittent duty S3
    4. The temperature sensors must be connected to electric pump control equipment. The temperature sensor tripping must cut the electric pump power supply. Reset must not be automatic, but should be possible only after inspection by qualified staff.
    5. No change to the machines or replacement of parts of the electric motors is allowed. It is allowed to only replace wet end parts with identical genuine parts (same part number or same code on the part) in case of normal wear and tear. Any service other than ordinary maintenance can only be carried out by Caprari S.p.A.
    6. The optional use of the conductivity sensor installed in the motor casing is conditioned on the use of a control device installed in the control panel and compliant with potentially explosive environment requirements.”
    7. Activate all possible measures to prevent the following malfunctions as they could cause and trigger an explosion:
    operation with no fluid in the pump or zero flow rate: arrange suitable direct control devices with manual reset on the control panel
    failure of pump shaft bearings: in case of an increase in vibration and/or noise in operation, stop the pump and send it to a Caprari authorised workshopOperation with inverter/converter:use of this kind of electronic equipment for control and adjustment must be carefully designed to make sure it does not generate any electromagnetic noise or induced current that would reduce the safety standard required by the ATEX class of the area where equipment is operating. The following conditions must always be complied with
    - mandatory use of inverters by Danfoss, series VLT FC202 or more recent Danfoss models having enhanced performance and characteristics; use of corresponding models from other brands must be authorised by Caprari S.p.A.;
    - mandatory setting for the internal switching frequency of the inverter at maximum 4kHz or at the lowest frequency allowed by the inverter;
    - mandatory installation on the inverter of suitable filters for reducing the [dv/dt], in-between inverter and motor;
    - mandatory use of the inverter only within 35-60 Hz modulation range.
    Max. standard ambient temperature is 40°C; on request, after Caprari S.p.A. checks, a maximum ambient temperature up to 60°C may be accepted, and this temperature will be indicated on electric pump nameplate.
  • What checks can be done if current imbalances are detected on the three phases of the motor?
    Absorption differences on the three motor phases (greater if detected without load) are not always due to a construction defect since even the supply can be unbalanced.
    If a high imbalance is detected (under optimal voltage conditions) also check absorption on the other two motor/mains connection combinations; (to maintain the same rotation direction, proceed according to the diagram):
    Optimal connection is when the difference between absorptions is the least. 
    However, if the highest absorption is always detected on the same phase of the line the main cause of imbalance is due to the supply.
    N.B.: Max. permissible imbalance on absorbed current: 5%.
  • What is the maximum temperature of the pumped liquid?
    The maximum temperature of the pumped liquid is 40° C.
  • How does a higher density of liquid affect motor power?
    A density higher than 1 Kg/dm 3 and/or viscosity higher than 1 mm 2 /s inevitably involves an increase of power absorbed by the motor, with subsequent overheating and burning of the winding if there are no thermal protectors. 
    Possible suggestions:
    Use a motor of higher power: the percentage increase in motor power must be at least equal to the density percentage. 
    Use of an impeller of smaller diameter than standard.
    To avoid possible obstructions and clogging, it is advisable to check that the velocity of the liquid in the delivery piping stays above 0.8-1 m/s. In the presence of sand, at least 1.6 m/s is required in the horizontal piping and 2.5 m/s in the vertical.
  • To ensure that a submersible pump functions correctly, what is the minimum level of fluid allowed?
    The minimum level of fluid required for a submersible electric pump immersed in that fluid differs, depending on the type of service (A1=continuous service/S3=intermittent service). This is why it is pre-engineered for installation of a cooling casing if required.
    S1 operation: the motor must be completely immersed in the pumped fluid. 
    S3 operation: the fluid can reach the base of the motor. However, the electric pump can only operate in these conditions for a certain period, alternated by the period at a standstill required by the motor.
    OPERATION WITH THE COOLING CASING: The motor can operate completely uncovered by the fluid in the S1 service mode.
  • What is cavitation?
    The phenomenon of cavitation is due to the formation and subsequent implosion of vapour bubbles forming inside the impeller blades due to an internal pressure lower than the vapour pressure of the pumped liquid at a given temperature.
    With waste water electric pumps cavitation can occur for the following reasons:
    • Suction pipe too long (only in the case of installations in dry chamber)
    • Intake of small quantities of air bubbles due to the creation of vortices caused by the dynamic level lower than m…
    • If the effective work duty point goes outside the normal electric pump utilization field
    • Water based liquids with temperatures above 80°C. 
      N.B.:  Cavitation can cause the following malfunctions:
    • Changes in hydraulic performance
    • Excessive noise (rattling)
    • Violent vibrations with possible failure of seals, bearings and the shaft
  • Can Caprari’s submersed electric pumps be used with electronic starting systems (Soft-Starter/Inverter)? If they can, are there any specific instructions to comply with?
    Standard submersed motors can also be used with multi-frequency starters. 
    The use and maintenance manual of the electric pump gives instructions that must be complied with if an Inverter or Soft-starter is used.
    General instructions for use of the INVERTER:
    - the minimum frequency must not be less than 70% of the rated value during the starting phase and/or use, with the voltage/frequency ratio maintained at a constant level. 
    A filter that ensures the following voltage gradient must be installed between the inverter and motor: 
    - (dV / dt) ≤ 750 V/µs for motors in oil
    - (dV / dt) ≤ 500 V/µs for motors in water and propylene glycol with standard winding and well tmax C ° ≤ 25 °C 
    - (dV / dt) ≤ 650 V/µs for motors in water and propylene glycol with special winding and well tmax C ° ≤ 35 ° 

    <= 1.5% harmonic voltage content. 
    <= 4 % harmonic current content.
    Conditions to be complied with regardless of the length of the power cables.

    General instructions for use of the SOFT-STARTER:
    The SOFT-STARTER device must be the voltage ramp and not the current ramp type.
    - always make sure that the soft-starter is cut out once the starting phase of the assembly has terminated.
    If an installation with a soft-starter or inverter starting system functions in a faulty way, check the operation of the electric pump assembly by connecting it straight to the electricity main (or to another device).
  • Can a Caprari K Series submersible electric pump be installed with an automatic coupling support (duck foot pedestal) by another producer?
    The possibility of coupling using adapters with the main coupling supports in production is provided for. 
  • How can I establish the correct direction of rotation of the electric pump?
    The terminals of the power cable are marked with the IEC international codes. Their correct connection to the L1(u), L2(v), L3(w) line ensures that the electric pump turns in the right direction. The arrow on the casting on the top part of the motor indicates the correct direction of rotation, i.e. clockwise viewed from above. If the installed unit is visible when started, it will be subjected to kick-back in the anti-clockwise direction.
    If it is impossible to directly check the direction of rotation (e.g.: when the electric pump is already installed), it is advisable to compare the hydraulic performance parameters and the motor’s electric power input with the electric pump’s data plate values.
    Switch two of the phases with each other to invert the sense of rotation.
  • How is the conductivity sensor connected to the electrical panel?
    If the Caprari electrical panel, already arranged for sensor connection, is not available, it is possible to ask the sales network for the appropriate CLM/3S-24V motor oil chamber water detection sensors.
  • What is the purpose of the "S" conductivity sensor in K Series models?
    The conductivity sensor is inserted in the oil chamber and detects any water infiltration in the chamber from the mechanical seal. If the electrical panel has a detection device just connect the terminal with the "S" symbol and a branch of the yellow/green earth wire.
    The conductivity detection device is used to activate an alarm circuit in the event water is detected in the oil.
    The alarm can be either visual or audible. For explosion proof motors the devices used must be intrinsically safe and compatible with the zone classification in which they are in use.
  • When should the oil in the electric pump oil chamber be changed?
    In normal operating conditions the oil must be changed every 10000/15000 hours.
    Use SAE 10W oil. If there is water in the oil, check the condition of the pump side mechanical seal and replace it if necessary.
  • How must K Series heat sensors be connected (T1 and T2)?
    The heat sensor terminals, marked with the symbols T1 and T2, must be connected in series to the electric pump command remote control switch coil (see the general cable wiring diagram in the operator's manual). The heat sensors are normally closed bimetal switches embedded in the motor windings. When the temperature of 132°C is exceeded they open, breaking the remote control switch coil feed circuit and causing the electric pump to stop.
    The coil is excited again when the sensors have cooled (114°C). The sensors can be connected with a max. of 250V. A power supply of 24V – 1.5°? is recommended.
    For pumps with explosion proof motors  (type ..X.. ) the connection of the temperature 
    probes is compulsory.  Failure to do so will invalidate the warranty.
  • Can K Series submersible electric pumps be used to pump drinking water?
    All the paints used have certification of suitability for contact with drinking water.
    Upon request the pump oil chamber, normally filled with mineral oil - viscosity SAE 10W, can be filled with dielectric oil approved by the Food and Drug Administration (U.S.A.) and suitable for contact with food substances.