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  1. #21
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    "That motor was still spinning" because it was probably a synchronous motor, with a PF correction of 1.0, look at the nameplate, others are .80.

    The run them to fix the Power factor"


    It's true that some synch motors run at a leading PF (like .8 leading) to help power factor. Most run at 1.0PF which helps PF but to a lesser degree. But in any case, anyone running a synch motor to correct PF each night is making a costly mistake when it's still connected to a compressor. That's because the wear and tear on the compressor is significant and will outweigh the PF savings. I'm basing that on a piston type compressor specifically but it would still be the case with a centrifugal. If your power co is hitting you that hard on a demand charge....you need to find a new power co.

  2. #22
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    The power company powering the pump in the OP is a company owned setup..isn't it? No peak demand charges there.

    Stuart

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    Quote Originally Posted by GregSY View Post
    but it would still be the case with a centrifugal. If your power co is hitting you that hard on a demand charge....you need to find a new power co.
    Nope not really, centrifugal s you can just spin em with the inputs closed, once the airs out they are just a spinning mass, most float on hydrodynamic bearings, so there really is no wear and tear in idleing. Power draws can be a hell of a lot smaller under no load than you would expect too.

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    Thinking on that....

    If bearings are hydrodynamic type, seems like the start up phase might put more wear on them than just letting them idle.

    Running cold, dry and direct metal on metal until they spin up.

    Sent from my SM-G960U using Tapatalk

  5. #25
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    Quote Originally Posted by mpmar_bt View Post
    Thinking on that....

    If bearings are hydrodynamic type, seems like the start up phase might put more wear on them than just letting them idle.

    Running cold, dry and direct metal on metal until they spin up.

    Sent from my SM-G960U using Tapatalk
    No, most larger machinery running that kinda bearing would have its own small motor and lube oil pump, often with a cooler too. Pretty std on all sorts of power generation turbines too.

  6. #26
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    Quote Originally Posted by SIP6A View Post
    Did you work at Willow Run?
    No. I worked at one of the Grand Rapids plants. The only one that's still open.

  7. #27
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    Quote Originally Posted by digger doug View Post
    "That motor was still spinning" because it was probably a synchronous motor, with a PF correction of 1.0, look at the nameplate, others are .80.

    The run them to fix the Power factor.
    Even on weekends with all machinery shut down it took a lot of air. With all the air leaks in a plant that size it would probably take a 100 hp compressor just to maintain proper pressure on the weekends with everything shut down. They occasionally would have a pipefitter come in on a Sunday when the plant was mostly idle and listen for leaks and tag them for repairs. It was way too noisy to hear leaks when everything was running during the week.

  8. #28
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    The plant I work at originally had 4 4600 (12 KV feed) hp Clark compressors. They were flat 6 cylinder double acting machines with 39" bore low pressure and 19.5" bore high pressure cylinders. They were bought used in the early '60s from natural gas pipeline compression service in Canada. Extensive modification had to be performed to convert them to air service, as the liberal oil injection used in gas compression would have been an explosion risk (dieseling) in air, as well as requiring extensive post compression oil separation. At maximum operating conditions we could get 3000 pounds/minute flow at 300 psi. We have air dryers to reduce the compressed air dewpoint to below -40º F, and natural gas fired heaters that can raise the temperature to 1000+ ºF. All of this is to simulate high stage bleed air from jet engines to test the aircraft environmental control systems we design and build. Only one of the 4 recips remains in operation, the rest having been replaced by smaller IR Centac centrifugals, which are more cost effective to run at variable flow requirements (and new parts are still available, unlike the Clarks.) We also added 6 38000 gallon receivers to help with peak demand flows.

  9. #29
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    Oh, you can still get all the Clark parts you want....they're now owned by (gulp) Siemens.

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  11. #30
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    Quote Originally Posted by adama View Post
    No, most larger machinery running that kinda bearing would have its own small motor and lube oil pump, often with a cooler too. Pretty std on all sorts of power generation turbines too.
    Yes sir, pre-lube.

    Sent from my SM-G973U using Tapatalk


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