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Thread: Why does higher voltage results in higher current drawn?

  1. #31
    Join Date
    Sep 2005
    Location
    Greenville SC
    Posts
    668
    Quote Originally Posted by Crowbar View Post
    Will the characteristics of the medium affect the current?
    Industrial hydraulic oil is COMMONLY one of 3 viscosity grades, ISO 32, 46, or 68. The optimum is properly selected to have the "correct" viscosity, as best possible, at all operating temperatures. Pumping and flow losses are higher with more viscous fluids, but the viscosity and losses vary significantly with temperature. Without detailed knowledge, it is impossible to quantify losses. With detailed info, it is still very difficult to do so.

    You are using a flow meter connected to the system output returning to the tank ... flow meters do have losses. BUT, to get a 10% change in flow suggests major instrumentation issues; a flow and current reading 110% higher one time than another with the pump rotating at the same speed ... and at the same pressure, else current would have varied far more than that would be unusual even if one fluid were kerosene and the other an ISO68 hydraulic oil.

    To help further, and industrial electro-hydraulic systems are my specialty, can you furnish, at the least, the pump make/model. Operating (not just maximum) pressure when tested would help. With any fluid in the pump's specification, I cannot imagine one fluid having 10% impact on volumetric efficiency. If it is not confidential, the system schematic would help.

    We are requested to not post email addresses in the forum, put permitted to exchange them via PM. I'm sending you mine; feel free to send the schematic and BOM for a review.

  2. #32
    Join Date
    Nov 2007
    Posts
    781
    Quote Originally Posted by Jraef View Post
    ABSOLUTELY!

    If I want to pump 1 liter/minute of water, and 1 liter/minute of peanut butter, the PB is going to require a LOT more energy.
    So the amount of difference in viscosity of your oil may not result in MUCH change, but 10%, sure, easily.

    https://blog.craneengineering.net/th...pump-selection

    So just to be clear, I'd bet a dollar that your test oil at the factory has a LOWER viscosity than the oil at the site, and in fact the temperature difference between sites likely had an effect as well.
    If it is a pump used to power hydraulic cylinders, I would believe it's the same type of hydraulic oil being used. The power formula (BHP) will be = GPM X psi /(1715 x efficiency).

    If you're familiar with these pumps, other than the speed factor, there is a relief valve that keeps the pressure within specs. What it does is to return some of the pumped fluid to the tank when the discharge pressure exceeds the setting. Perhaps the setting was changed causing the change in load.

  3. #33
    Join Date
    Feb 2016
    Location
    Illinois
    Posts
    404

    Why does higher voltage results in higher current drawn?

    Quote Originally Posted by Jraef View Post
    ABSOLUTELY!

    If I want to pump 1 liter/minute of water, and 1 liter/minute of peanut butter, the PB is going to require a LOT more energy.
    So the amount of difference in viscosity of your oil may not result in MUCH change, but 10%, sure, easily.

    https://blog.craneengineering.net/th...pump-selection

    So just to be clear, I'd bet a dollar that your test oil at the factory has a LOWER viscosity than the oil at the site, and in fact the temperature difference between sites likely had an effect as well.
    But that does not explain the increase in flow!

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