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Re: [pumpfundamentals] Discharge Throttling & high Ele.Current

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  • S. L. Abhyankar
    Dear Mr. Jacques Chaurette, My mail to Mr. A. Rahman bounced back. Pl. check and forward suitably. Regards, SLA ... From: Mail Delivery Subsystem
    Message 1 of 6 , Feb 15, 2012
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      Dear Mr. Jacques Chaurette,

      My mail to Mr. A. Rahman bounced back.

      Pl. check and forward suitably.

      Regards,
      SLA

      ---------- Forwarded message ----------
      From: Mail Delivery Subsystem <mailer-daemon@...>
      Date: 16 February 2012 11:18
      Subject: Delivery Status Notification (Failure)
      To: sl.abhyankar@...


      Delivery to the following recipient failed permanently:

          mahmoudkrc@...

      Technical details of permanent failure:
      Google tried to deliver your message, but it was rejected by the recipient domain. We recommend contacting the other email provider for further information about the cause of this error.

      ----- Original message -----


      Subject: Re: [pumpfundamentals] Discharge Throttling & high Ele.Current
      From: "S. L. Abhyankar" <sl.abhyankar@...>
      To: mahmoudkrc@...
      Cc: pumpfundamentals@yahoogroups.com,
             Juned Ansari <juned.ansari@...>
      Content-Type: multipart/alternative; boundary=14dae934052b4525b504b90e6276

      Dear Mr. A. Rahman,

      It seems that although the pumps are rated for a head of 50m for 330 m3/h,
      the head in the system is much less.

      If actual system with static head of say 30m, is flat and system head at
      330 m3/h is say, 40 m the pump will actually run delivering 410 m3/h with
      system head of 45m. Power required by pump will be about 77 kW. This will
      overload the motor.

      Does this explain ?

      Cordially, S. L. Abhyankar

      http://slabhyankar.wordpress.com
      http://study1geetaa2sanskrit.wordpress.com/
      http://slez-musings.blogspot.com


      On 15 February 2012 19:11, a.rahman <mahmoudkrc@...> wrote:

      > **
      >
      >
      > Under commissioning, Three Vertical centrifugal pumps connected in
      > parallel on Azud filtration unit , to boosts and to circulate cooling water
      > for air compressors in to cooling water system .
      > Each pump capacity 330 m3 /h , total head 50 m Ensine Power 75kw and speed
      > 1450 rpm , the electrical induction motor = 75kw ,380 V, 50HZ , 140A and
      > rpm =1480 .
      > Each pump DN connection , in /out = 250mm the header connection 300mm .
      > Our question when starting one or two pump we can not be able opening the
      > out let valve more than 30% (discharge throttling ) the motor current reach
      > near 140 A , so Why is the current of the motor near overload set point
      > while the out let valve throttling & the out let pressure beyond the out
      > let valve bigger than the pressure after the out let valve what is the
      > problem ?
      > mohdzain
      >



      --
      Cordially, S. L. Abhyankar

      http://slabhyankar.wordpress.com
      http://study1geetaa2sanskrit.wordpress.com/
      http://slez-musings.blogspot.com
      Tel. +91 22 2849 5365
      Mobile +91 9757 21 5527





    • Juned Ansari
      Dear Mr Abhyankar, I agree with your analysis. I too would have come to the same conclusion after getting aware of the pressure in working condition which I am
      Message 2 of 6 , Feb 15, 2012
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        Dear Mr Abhyankar,

         

        I agree with your analysis. I too would have come to the same conclusion after getting aware of the pressure in working condition which I am sure would be less than the rated pressure. The pumps are not suitable for the system.

         

        Thanks!

         

        Regards

        Juned Ansari

        Secure Meters Limited

        Assistant Manager

        M: +91-96655-86331

        NBI Water

        Energy Auditor (EA-9789)

        M: +91-94221-61420

        Aurangabad

        From: S. L. Abhyankar [mailto:sl.abhyankar@...]
        Sent: 16 February 2012 11:19 AM
        To: mahmoudkrc@...
        Cc: pumpfundamentals@yahoogroups.com; Juned Ansari
        Subject: Re: [pumpfundamentals] Discharge Throttling & high Ele.Current

         

        Dear Mr. A. Rahman,

        It seems that although the pumps are rated for a head of 50m for 330 m3/h, the head in the system is much less.

        I assume pump characteristics as follows -

        m3/h

        H one pump

        Pump Input kW

        System

        0

        60

        30

        100

        59

        40.2

        30.9

        200

        56

        53.5

        33.7

        330

        50

        67.1

        40

        450

        43

        81.1

        48.6

        600

        33

        89.9

        63.1

        330

        0

        330

        67.1

        410

        0

        410

        77

         

        *



        If actual system with static head of say 30m, is flat and system head at 330 m3/h is say, 40 m the pump will actually run delivering 410 m3/h with system head of 45m. Power required by pump will be about 77 kW. This will overload the motor.

        Does this explain ?

        Cordially, S. L. Abhyankar
        सस्नेहम्, अभ्यंकरकुलोत्पन्नः श्रीपादः | "श्रीपतेः पदयुगं स्मरणीयम् "
        http://slabhyankar.wordpress.com
        http://study1geetaa2sanskrit.wordpress.com/
        http://slez-musings.blogspot.com

        On 15 February 2012 19:11, a.rahman <mahmoudkrc@...> wrote:

         

        Under commissioning, Three Vertical centrifugal pumps connected in parallel on Azud filtration unit , to boosts and to circulate cooling water for air compressors in to cooling water system .
        Each pump capacity 330 m3 /h , total head 50 m Ensine Power 75kw and speed 1450 rpm , the electrical induction motor = 75kw ,380 V, 50HZ , 140A and rpm =1480 .
        Each pump DN connection , in /out = 250mm the header connection 300mm .
        Our question when starting one or two pump we can not be able opening the out let valve more than 30% (discharge throttling ) the motor current reach near 140 A , so Why is the current of the motor near overload set point while the out let valve throttling & the out let pressure beyond the out let valve bigger than the pressure after the out let valve what is the problem ?
        mohdzain








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