Announcement

Collapse
No announcement yet.

Turn off or leave on?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Turn off or leave on?

    J have a VFD on my mill. My working pattern is that I generally do about an hour in the shop then take about half an hour break and then return. Is it better for the electronics in the magicbox( yes I am electrically challenged) to turn the main power off for the half hour or so that I am away or is it kinder to the capacitors etc to simply to leave the main switch on while I am away? ( The display on the VFD is on all the time the main power is on) Regards David Powell.

  • #2
    My vfd is guaranteed for 15000 power up cycles, maximum 2 per minute.Check out your own spec.

    Although this is a finite number it will be fine whatever way you preferr....unless you are going to live to 400 years old
    "...do you not think you have enough machines?"

    Comment


    • #3
      I would leave it on. When you switch on the power you never know where you are on the sine wave. So, sometimes you get a big inrush and things like light bulbs pop. If you are coming back anyway probably less stress on the components to leave them on, especially if they are well ventilated. My $.02 for what it's worth.

      Side note: whenever I buy electronics I bring them home and leave them on for 48 hours straight. If it does not have any probablems after that extended time it will probably work reliably for years. This technique has not failed me yet.


      Regards,
      Kevin

      Comment


      • #4
        As an electronics engineer I'd say if the idle period (on modern electronics)
        is an hour or less leave it on. Much longer than that I'd turn it off.
        Now in the 40s and 50s with vacuum tubes things were a little different.
        We ran some tests on the CPS6B radar in 53. Almost all of the down time
        occured right after a scheduled maintenance where the power was
        off for an hour or two. So the head shed came up with a program
        I think was called " curtail maintenance " we just ran it till something
        quit and the downtime droped by a lot.
        But there isn't a lot of "surge"/inrush problems with modern stuff.
        So it's not a big deal realy. Fluroscent lamps on the other hand do
        wear out faster with on/off cycles.
        ...lew...

        Comment


        • #5
          Prolly a lil different but.. Back in the 80s I worked on a ship that shot guided missiles. I was responsible for pressing the green flashing button when we wanted a bird off the rail, oh, and responsible for maintaining the electronics that guided the bird once in flight. Mk-92 FCS

          We had prolly 15, 2x3 foot electronic enclosures. Some of them housed just circuit boards, maybe fifty boards per cabinet, some cabinets house very high power tube drives, klystrons, magnetrons, and others drives for the servos moving the antennas, pretty large weapon system.

          In port we were required to fire the entire system up and run it through the paces, even loading up a bird, a blue bird (dud), Long Beach residents frowned upon seeing a white bird on the rail LOL

          So we would run the system, perform adjustments, troubleshoot faults and the various mundane work when sitting in port, then shut it off for the night. We were going through circuit boards at the rate of one maybe two a week averaged over six months, at 15-20 grand a board. We were trained in mico-miniature repair, and would troubleshoot it down to component level, but with the pricey contract we had with raytheon we would have to swap the board out from supply. Oh, the schematic diagrams provided took up 27 volumes. A stack of binders five feet tall, I loved those schematics, perfect in every way. We had them all customized with propper waveforms when the system was tight. So during trooble shooting we could refer to our hand drawn notes and drawings and see the fault. Nice to have those notes, sometimes a good waveform note, when the system was working would save our buts when she wasnt acting just right. Not a solid failure, but outta spec. That was our lead that decided to map out all the critical waveforms when the system was tops. Oh where are you now Ray, he went on to work at Fermi, never head from him again.

          So we were eating boards up like they were free while in port. When we were out to sea, sometimes for a month before porting the system was never turned off, seven eleven style, 24-7 she was hot. We could go an entire month (and longer) without having ANY component failures. We all noticed it. Had six guys in our work center. We thought about crummy shore power but ruled that out. An O-scope showed much cleaner shore power compared to what the BIG diesel generators were feeding us at sea.

          Transient spikes, voltage and current from turning the system on were causing a dramatic failure in circuit components. And the system was pretty hardened for external EMP, and that included the supply lines. Even the main frame computer, which was protected more was susceptible to the constant powering on and off.

          Ive come to believe, no real data to prove it though, that electronic equipment loves to stay lit. I never turn off my desktop computer, never had a failure besides the fans LOL Yeah, they do start getting noisy and fail. But purely electronic devices like to have some electrons moving in them. A constant stream, not a sudden peak to give them a heart attack.

          Long story huh? Yeah. Just reminiscing... Oh, Ive got a radio in my garage thats been on for ten years now, I imagine it will be on for another ten years... JR
          My old yahoo group. Bridgeport Mill Group

          https://groups.yahoo.com/neo/groups/...port_mill/info

          Comment


          • #6
            Lew: In 1956 at NAS Brunswick, GA we ran half of the rooms (simulating CICs in USN ships) 24/7 and the other half turned off daily; usually for about 8-12 hours. Less failures on the 24/7 rooms. However, the cost of shore power to operate the systems for 24/7 balanced cost of repairs of the turn off units.
            Damned if you do and damned if you don't.
            These were vacuum tube equipments for the most part.
            Solid state stuff may have a different story. Sometimes I leave it on and sometimes I turn it off. Depends on how I feel that day.
            Not very definitive, but it works for me.
            John Burchett
            in Byng OK

            Comment


            • #7
              I'll 2nd what JR says. Leave it on.

              The VFD has capacitors in the front end that must be charged. Turning it off will allow them to bleed down (or be discharged by protective circuits). In spite of the fact that the VFD may have a slow start circuit to avoid damaging the caps, they still need to charge again before use.

              There isn't much power dissipated when the VFD is "idling" either so there is no "green" reason to turn it off.

              kc5ezc, heat is still the major killer of electronics. Even at the low power dissipated in an "idling" VFD, there is still a small amount of heat generated. With today's surface mounted components and the "iffy" nature of the more brittle lead-free solders, it's a good idea to leave things on for more constant temperature.

              Den
              Last edited by nheng; 03-07-2009, 11:55 PM.

              Comment


              • #8
                The only time my desktop puter gets shut off is on a power failure and haven't had a problem with it yet and it's about 5 years old. 2 year old laptop is off and on several times a day and the damn hinge broke off, plastic piece of chit. My previous desktop puter was on all the time too and the harddrive bearings started squaling like a pig under a gate. It started squaling after about 3 years. The current harddrive must have better bearings.

                Patrick


                Edit: New laptop was supposed to be here last week. Seems to be lost somewhere. Thanks UPS.
                Last edited by HSS; 03-08-2009, 09:23 AM.

                Comment


                • #9
                  Originally posted by HSS
                  The only time my desktop puter gets shut off is on a power failure and haven't had a problem with it yet and it's about 5 years old. 2 year old laptop is off and on several times a day and the damn hinge broke off, plastic piece of chit. My previous desktop puter was on all the time too and the harddrive bearings started squaling like a pig under a gate. It started squaling after about 3 years. The current harddrive must have better bearings.
                  This helps with the bearings JR

                  My old yahoo group. Bridgeport Mill Group

                  https://groups.yahoo.com/neo/groups/...port_mill/info

                  Comment


                  • #10
                    For the time frame you are talking about, I'd leave it on.

                    Thermal cycling of traces and components along with inrush are points of failure.

                    Anyone have an idea what a vfd idling pulls? Full wave rectifier keeping the buss hot with fully charged capacitors doesn't seem like much of a load to me.

                    Clutch

                    Comment

                    Working...
                    X