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Recent content by CB2

  1. CB2

    Modulated (vsd) pumps versus throttle valves

    I would suggest you watch Goulds and how they are doing with their "Pump Smart" accessary product. There are a number of other pump manufacturers about to introduce similar options. Does that put the control valve future in question?
  2. CB2

    New ground rod test with a meggar

    Sorry, the "ground rod" is installed in the ground.
  3. CB2

    New ground rod test with a meggar

    How do you test a new ground rod with what I think is a standard Meggar(three wires, red, black, and green)? This is a new installation and I need 25 Ohm or less. Thanks for the help CB2
  4. CB2

    FLA Formal Definition

    I am late into this discussion and a little suprised there is no mention of temperature until April 13th posts. I think buzzp brings up a very important factor about motors and their ratings. The definition of a motor is " an electro/mechanical device that is thermally rated".
  5. CB2

    1000 hp pumps (4160 volt each with itÆs own VFD)

    andy32821, Your question can be answered with a generality as to energy consumption, "best to run multiple pumps at the same speed". To get a better answer you need a system curve, the pump curves, and an energy analysis software porgram. The system curve will provide the...
  6. CB2

    Fatality in Water Valve Manhole

    Hairman, KRS Services comments are very accurate and save lives. I will add that the "confined space" need not be so confined to be deadly. Know of a case where two workers were killed when working at the exit of a large strom drain culvert. A low area and a very calm day, H2S at...
  7. CB2

    Flow control centrifugal pump with frequency drive or control valve?

    MVD Generally your application will work well. I have done similar applications for feeding DI filters, primarily for energy savings.
  8. CB2

    Use of VFD output side contacter for E-stop

    If you remove power from a vfd without removing the start/run command the vfd will see the removal of power as an under voltage condition, the energy stored in the DC bus and motor/load inertia will allow the vfd to continue running untill the dc buss voltage decays to a shutdown condition...
  9. CB2

    source of analog 4-Q dc drive controllers

    I talked with a Reliance (Rockwell Automation) person, and they gave me the following to call, 626-969-7647. It seems that they still have the capability but it will be custom with an appropriate price. Goog luck.
  10. CB2

    source of analog 4-Q dc drive controllers

    Go to "www.drives-mag.com" and click on "marketplace", and DC drive manufacturers. This has a list of about 15 viable DC drive manufacturers, MAYBE one still does analog. Be aware that the people that study market trends report that the DC drive market is shrinking by about...
  11. CB2

    Variable Freq Drive on a Fan?

    I see alot of VFD retrofits on the type of fan you have. Primary reason is failure of the "adjustable pitch" controls due to lack of quality and maintenance. Lock the vains to full open and integrate a VFD to the system. Energy savings for fan and pump applications using VFDs are...
  12. CB2

    Heating of motor by using frequency converter

    What kind of amp meter are you using to measure amperage? The output of the VFD is not a standard syn wave and can not be measured with the common digital meters. Use either an old style iron movement meter or a true RMS meter. What does the VFD say the output current is?
  13. CB2

    DC Motor Replacement with AC

    jOmega, suggest you check out the ABB model ACS800-17 Regenerative VFD, 75 to 1,250 Hp, active front end. The front end of this VFD has 2% current distortion, 2% voltage distortion, power factor can be controlled leading or laging, all in both motoring and regen modes. Standard product but...
  14. CB2

    ASD savings based on pump motor loading??

    Rule of thumb: For centrifugal loads, 10% reduction in speed results in a 20% reduction in power demand. See centrifugal affinity laws. CB2
  15. CB2

    DC Motor Replacement with AC

    As long as you are matching the base speed of the motors, this should be a simple change out. Purchase an "inverter duty" motor, and I would not worry about output filters unless the motor wire runs are >500'. I see your biggest risk in selecting a VFD vendor. The size you are...
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