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  • PA off electric Generator, Inverter Required?

    Will standard generators destroy expensive PA gear leaving only pure sine wave inverter generators safe to use, OR is it ok to use a large 3,600 rpm generator?

    There are times when I need to run PA off generators for a DJ setup. Some older and experienced djs mentioned that the only type of generator to use is a "pure sine wave inverter generator" and say that other generators will destroy equipment if used long enough. Other djs with long experience do not seem to be worried about that issue. I read that power conditioners simply do not address this power issue. I look through the net and find conflicting information. Some things seem to indicate that if the engine speed is 3,600 rpm the power should be fine, while others say that an inductive load (which requires more power at times and less at others, typical of dynamic music) really needs a good inverter generator to maintain sine wave power. It seems that with normal generators voltage and frequency can change and this can damage capacitors (and perhaps other components). Some things say that motors will vary in speed and any variance affects the electricity generated. Does anyone here have experience or knowledge in this field. Pure sine wave inverter generators are much, much more expensive than regular generators. What are your thoughts?
    Thanks!

    http://www.solarlink.de/PDF-Files/Sterling/generatorbenzin.pdf

    http://www.hondapowerequipment.com/products/generators/content.aspx?asset=gg_inverteradvantage

    http://bellsouthpwp.net/j/o/johngd/files/rv/inverter_generator.pdf

    http://en.allexperts.com/q/Electronics-3923/2009/1/Inverter-vs-non-inverter.htm

    http://www.arrl.org/files/qst-binaries/QS0608Kleinschmidt.pdf

    http://www.angelfire.com/planet/als_space/ham/Generators.pdf
    ---------------
    I also saw the following statements around:
    "All models of two bearing generators MUST operate at 3600 R.P.M. If the generator speed os less than 3600 R.P.M., the voltage and frequency (hertz) will be lower than required and if the generator operates above 3600 R.P.M., the voltage and frequency (hertz) will be higher than required. Either condition will cause damage to the items being operated by the generator and also to the generator. Generator shaft speed below 3400 R.P.M. and above 3800 R.P.M. will cause damage to items and the generator. "

    [this is +/- 5% flux and I see some generators spec at 5%]
    --------------
    Generators
    In many countries without fully developed electrical power distribution systems, the use of generators is common. Generator supplies can be very good, however, in many places they are not, and can cause damage to sensitive equipment if it is connected. The voltage, frequency, and waveform shape (it should be a smooth sine-wave) can vary. In some places, people modify generators to run faster. This gives more voltage and power but increases the frequency too. The part of a generator that keeps it running at a constant speed is called the governor. If this is tampered with, the output voltage could rise sufficiently to cause damage. The best advice is not to connect valuable equipment to the supply, or at the very least disconnect it as soon as it is finished with.

    If you are unsure about the quality of generator in use, there are a few simple rules. If it runs from petrol/gasoline it is bad - anyone serious about using generator power uses a diesel oil powered system. A good quality generator will have a low engine speed. 1500RPM for 50Hz or 1800RPM for 60Hz. If the engine speed is 3000RPM+, it is not a good machine.
    ======================================
    
    						
    Shelby Hoyl
    DJDFW
    A Wedding DJ
    http://www.djdfw.com
    http://www.myspace.com/djdfw

  • #2
    What a bunch of cock and bull information.

    1. the RPM is a function of the number of poles on the generator. 2 pole is 3600 RMP, 4 pole is 1800 RPM, 8 pole is 900 RPM etc.

    2. All generators are "pure sine wave". That's how a generator works. Period.

    3. Inverter generators (generally, though marketingspeak can alter the real meanings of words) refers to the exciter supply and how the voltage regulation is handled.

    4. There are good gasoline/petrol generators, They are not going to be "cheap".

    5. There are bad diesel generators (not all that many though).

    6. All generators should be operated with a ghost or dummy load of around 2% of their rated load or 200 watts, whichever is greater. This improves the voltage regulation under light inductive loads.

    7. For large dynamic loads (audio and stahge lighting can fall into this catagory), it's common to derate the generator's capacity by 50%. This improves dynamic performance of the generator system.

    8. Proper maintenance is essential with all generators.

    Inverters (DC-AC) do come in sine wave, modified sine wave or square wave flavors. Sine wave inverters are PWM type, and are the best to use for audio provided they are of sufficient quality and you have sufficient battery capacity. Most are not.
    -------------------------------------------------------------------------------------------------------------------------------------------------------------------
    Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

    Currently product development engineer: Mesa Boogie

    Comment


    • #3
      Thank you. The information I was finding was very confusing to me. What I probably need to get then is a standard generator of about double the wattage of the amps/electronics I will use on it.

      Do you think a regulator such as the Furman AR1215 AC Line Voltage Regulator is necessary http://www.zzounds.com/item--FURAR1215 ? I normally run a Furman with the led voltmeter and the meter has proved useful, but I don't know if a regulator for each amp would be necessary.

      Thanks again.

      OK, I read one of your posts about not using amps on a regulator, so I guess that answers that question. : )
      Shelby Hoyl
      DJDFW
      A Wedding DJ
      http://www.djdfw.com
      http://www.myspace.com/djdfw

      Comment


      • #4
        Thank you. The information I was finding was very confusing to me. What I probably need to get then is a standard generator of about double the wattage of the amps/electronics I will use on it.

        Do you think a regulator such as the Furman AR1215 AC Line Voltage Regulator is necessary http://www.zzounds.com/item--FURAR1215 ? I normally run a Furman with the led voltmeter and the meter has proved useful, but I don't know if a regulator for each amp would be necessary.

        Thanks again.


        I wouldn't recommend this. First and foremost, you shouldn't need one. If the venue power is that bad, don't play.

        A *good* regulator will cost a lot more than the Furhman you show as an example. It should be noted that regulators will correct voltage but at the expense (nothing's free) of current. Power (watts) is a constant. In the case of a regulator that can use a typical 15a wall plug, if supply voltage drops to 95 volts, the available current is less than 12 amps. In other words, you always need more current capacity in order to compensate for lower voltage. If the venue service is crappy, this becomes a cascading problem...as voltage drops a regulator draws more current to compensate, and this larger load reduces voltage further.
        "If you don't know where you are going, you might wind up someplace else" - Yogi Berra, 1925-2015

        Comment


        • #5
          I had been thinking of using the regulator to cover voltage changes when using a generator outdoors, but using a generator that would supply twice the watts of the amps and equipment used, so there should be extra power to compensate.

          The Furman I normally use at venues is an inexpensive conditioner that basically serves as a group of plugs with a led voltmeter and lights for the rack. I use a probe tester of the outlet before plugging anything in and if a lot of power is needed, I will plug into a separate circuit (have a tester for this too to be sure it is a separate circuit) for the sub amp. I also bring a box with four plugs on each side with each side on with separate 15A breakers and the outlet goes to a 20A connector which also has a 15A adapter.

          Haven't bought a regulator or generator yet and am looking through as much info as I can find to try to understand how they work so I don't burn anything upallgone and I can understand how to address any problems or failures. Even in the middle of Dallas/Fort Worth, we sometimes have to use generators because the venue ties all their electricity up with festival bs. We are mobile PA/DJ.

          To take the horseman out of context, I read in a current "power conditioner" thread:
          "Power amps should never be on a voltage regulator unless there is a very specific and well defined fault and correcting for it won't cause a much bigger fault.

          I will never use a voltage regulating device without understanding exactly how it works so that I can analyze the entire system under dynamic conditions for possible failure modes (soft white underbelly)."

          Looking at the manual specs for the amps, I see no listed tolerance for flucuations in voltage or frequency on the power supply...
          Shelby Hoyl
          DJDFW
          A Wedding DJ
          http://www.djdfw.com
          http://www.myspace.com/djdfw

          Comment


          • #6
            A voltage regulator could cause the generator to hunt. Bad end result.

            Amplifiers will not have this spec, it's a function of many variables and you need to understand control system stability concepts to analyze this. The electrical load varies with the dynamics of the music and so does the inlet power voltage. As the current increases the voltage decreases due to line impedance. Now as the voltage decreases the regulator increases the voltage which increases the current which increases the voltage drop and there exists the potential for positive feedback and oscillation. A fatal happening.
            -------------------------------------------------------------------------------------------------------------------------------------------------------------------
            Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

            Currently product development engineer: Mesa Boogie

            Comment


            • #7
              From a strictly empirical standpoint (I dont' have Aged's EE background), I run Everything from a Pioneer CDJ-1000 to QSC amps off of a Somewhat standard 6500w Honda Genny. It's not one of the inverter types. Gear works fine. I've removed all my AVR gear from my Amp racks, and only use it work more delicate stuff.

              Todd A.
              My Rig:

              EAW LA325's (2)
              EAW LA400's (4)
              QSC PLX 3402 (2)
              QSC PL1.8
              QSC RMX 2450
              Ashly ProTea 3.24c
              Ashly ProTea 4.24G
              EAW LA212 Monitors
              JBL PRX-512M Monitors
              Whole Lotta Cables

              Comment


              • #8
                A voltage regulator could cause the generator to hunt. Bad end result.

                Amplifiers will not have this spec, it's a function of many variables and you need to understand control system stability concepts to analyze this. The electrical load varies with the dynamics of the music and so does the inlet power voltage. As the current increases the voltage decreases due to line impedance. Now as the voltage decreases the regulator increases the voltage which increases the current which increases the voltage drop and there exists the potential for positive feedback and oscillation. A fatal happening.


                I had a flashback to a time when I asked Edward Teller a question about nuclear physics. BUT, I think I get the idea on why and it really makes good sense.

                Some of that hip hop bass really pulls down the voltage in the middle of a song and I could see how something like this could happen.

                Thank you very much for your time and information. We haven't gone with a generator because we wanted to understand more first as to whether we could use a regular generator or HAD TO HAVE one of those inverter types.
                Shelby Hoyl
                DJDFW
                A Wedding DJ
                http://www.djdfw.com
                http://www.myspace.com/djdfw

                Comment


                • #9
                  Some of that hip hop bass really pulls down the voltage in the middle of a song and I could see how something like this could happen.


                  Absolutely.
                  -------------------------------------------------------------------------------------------------------------------------------------------------------------------
                  Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

                  Currently product development engineer: Mesa Boogie

                  Comment


                  • #10
                    Interesting thread! We are playing a small outdoor event on Tuesday and we have a 5500 watt generator. Do you think we will have any issues using it with our gear? We are not using any lighting either.

                    Amps:
                    Peavey CS4000
                    Peavey CS2000
                    Peavey PV2600
                    Peavey PV1500
                    Peavey PV1500

                    Thanks!

                    Comment


                    • #11
                      Interesting thread! We are playing a small outdoor event on Tuesday and we have a 5500 watt generator. Do you think we will have any issues using it with our gear? We are not using any lighting either.

                      Amps:
                      Peavey CS4000
                      Peavey CS2000
                      Peavey PV2600
                      Peavey PV1500
                      Peavey PV1500

                      Thanks!


                      Yes... you have too much dynamic load for the genny. Time to step up to a more commercial unit. I assume there will be some back line too?
                      -------------------------------------------------------------------------------------------------------------------------------------------------------------------
                      Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

                      Currently product development engineer: Mesa Boogie

                      Comment


                      • #12
                        We also have a Honda 12000 watt generator. Could we run the backline on the 5500 watt genny and the FOH gear on the 12000 watt honda genny?

                        Comment


                        • #13
                          Maybe that would work, but be sure you have a dummmy load (say 200 watts of lights) on the gennys all the time, and turn off the econo-functions.

                          Also, you should electrically connect the two generator frames together and insure that the ground-frame bonds are properly connected on each generator. Then connect the frame(s) to a properly driven ground rod.
                          -------------------------------------------------------------------------------------------------------------------------------------------------------------------
                          Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

                          Currently product development engineer: Mesa Boogie

                          Comment


                          • #14
                            Maybe that would work, but be sure you have a dummmy load (say 200 watts of lights) on the gennys all the time, and turn off the econo-functions.

                            Also, you should electrically connect the two generator frames together and insure that the ground-frame bonds are properly connected on each generator. Then connect the frame(s) to a properly driven ground rod.



                            HOLY CRAP!
                            OK, you guys always come up with a new thread that throws me for a loop, but I had no idea about the Generator do's and don'ts.
                            I have an event in October, and I have been running the sound from a Towable 20KW diesel Generator for years now.
                            I don't have any "regulators", but I do have Furman Line conditioners.
                            Also, I had no idea about the Dummy load. I can make sure I have lights plugged in.

                            As far as the ground frame bonds....alright now my head is swimming.
                            I don't get this part at all.

                            Comment


                            • #15
                              You don't need external regulators, the generator has this built in via the field winding compensation current. In fact, external regulators and dynamic loads can cause additional problems.

                              The "line conditioners" aren't much if any help either, but they are a convenient power strip.

                              The genny frame should be bonded to the "neutral" on your genny already, a driven ground rod connected to the genny frame is for safety. It can also reduce noise (hum, buzz and RFI) with some equipment.
                              -------------------------------------------------------------------------------------------------------------------------------------------------------------------
                              Former product development engineer: Genz Benz, a KMC Music/FMIC/JAM Industries Company, continuing factory level product support and service for Genz Benz

                              Currently product development engineer: Mesa Boogie

                              Comment













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