[QuadList] Mains frequencies, control, similarities to genlocking

Sun Apr 11 03:10:13 CDT 2010

Brian...

It's interesting that you should mention that, because that's precisely an event that Akai in japan went through (by their own rotten doing) from about 1963 to 1968.

They sold the Akai tape recorders in the U.S. under the Roberts label. In 63, while still in high school I worked at Westlake TV and HiFi in Daly City, just outside of San Francisco. A Navy nuclear sub docked and a whole bunch of sailors came to the store looking for warranty repair on their Akai tape recorders, all with burnt out power transformers. The same problem we were seeing with a slew of Roberts decks. Akai had tried to cut some corners on the assembly line with some of the 50hz power transformers and it backfired. Or maby I should say..."backsmoked".

When I was stationed in Japan from 1965 to 1967, I was able to learn all about the real background of Akai, from the japanese people themselves, and it was'nt pretty. Akai was just a brand that was really born for the "Kanazawa" HiFi circuit, a contract company that ran the electronics department up and down the country in all the  U.S. base exchanges. Two company's in particular stood out, that mainstream Japanese consumers would'nt touch with a ten foot pole. Akai, and Sansui.  Purely junk, and peddled to the U.S. military as being really high class. 

I opened up a Sansui 1000 receiver one time, the one that sold more than any of their other products. The first thing that set off some red flags...the auxiliary AC receptacles on the back, were wired with #22 solid hookup wire. The same stuff I was using on my American Flyer trains as a kid.  Fine for the amplifier circuitry, but not quite AC accessory outlet proper.

A friend of mine at Ashiya, that ran the local TV and Stereo and Appliance store, got me a copy of the Sansui annual report, a nice little color booklet that showed all of it's divisions and products. Their primary productline and business, was AC power distribution equipment for the public utilities. Sort of like GE or Westinghouse or Allis-Chalmers here in the U.S.  Transformers, oil circuit breakers and the like. In the very back of the annual report, 1 page with pictures and description saying basically "and we're also in the consumer hi-fi business with a few products". Like Akai. Sansui audio gear was very seldom bought by the Japanese people because they knew better.

All the best to all of you,

Steve Spears
Orrs Island, Maine
www.kel.com
  ----- Original Message ----- 
  From: Gideon4 
  To: Quad List 
  Sent: Saturday, April 10, 2010 5:13 PM
  Subject: Re: [QuadList] Mains frequencies, control,similarities to genlocking

  Re the 60/50Hz business, one of the Gotchas is transformer overheating, or to expand,  A transformer designed for 60Hz has slightly less Iron in it than the comparable 50Hz one. If you have a "budget transformer" in a item of kit from a 60Hz source, they would often saturate on 50Hz, get hot and burn out. Been there, done that!

  Brian Summers
    -----Original Message-----
    From: quadlist-bounces at quadvideotapegroup.com [mailto:quadlist-bounces at quadvideotapegroup.com]On Behalf Of Ted Langdell
    Sent: 10 April 2010 19:22
    To: Quad List
    Subject: Re: [QuadList] Mains frequencies, control,similarities to genlocking

    On Apr 10, 2010, at 10:53 AM, Chuck Reti wrote:

      Not documented anywhere I've looked, but wonder if 60Hz might have been chosen since it correlates with 60sec/min - 60min/hr timekeping.
      Did make it easier to do electric clocks!
      -- 
      Chuck Reti
      Detroit MI

    Keeping time with motor-based clocks is an interesting situation. See the link and text below.

    The process has some elements of pre-framesync Genlock... (Think rubidium) and since this is Saturday, would have been something networks were doing with sports events from remote locations.

    Googling "Genlock Remotes" brought up a 2009 patent application by CISCO, the data router people in regard to Genlocking remote video sources:
    http://www.wipo.int/pctdb/en/wo.jsp?WO=2009105593&IA=US2009034598&DISPLAY=STATUS

    Genlock and framesyncs turn up in the April "CBS Retirees Ramblings" here:
    http://www.cbsretirees.com/blog/blogger.html

    You'll see a couple of items from Harold Deppe (Sr.,) who was in Maint. at CBS in NYC and is on the QuadList.  We may have the only Father/Son pair of engineers on a video-related discussion list, for all I know.

    Back to power for a tad:

    The section below on Frequency and Load has me wondering whether it would be practical to monitor the powerline freq., with limit alarms to indicate that a power "event" like a brownout, load shed or blackout was about to happen.

    Ted

    http://en.wikipedia.org/wiki/Utility_frequency#Long-term_stability_and_clock_synchronization
    Long-term stability and clock synchronization
    Regulation of power system frequency for timekeeping accuracy was not commonplace until after 1926 and the invention of the electric clock driven by a synchronous motor. Network operators will regulate the daily average frequency so that clocks stay within a few seconds of correct time. In practice the nominal frequency is raised or lowered by a specific percentage to maintain synchronization. Over the course of a day, the average frequency is maintained at the nominal value within a few hundred parts per million.[17] In the synchronous grid of Continental Europe, the deviation between network phase time and UTC is calculated at 08:00 each day in a control center in Switzerland, and the target frequency is then adjusted by up to ±0.02% from 50 Hz as needed, to ensure a long-term frequency average of exactly 24×3600×50 cycles per day is maintained.[18] In North America, whenever the error exceeds 10 seconds for the east, 3 seconds for Texas, or 2 seconds for the west, a correction of ±0.02 Hz (0.033%) is applied. Time error corrections start and end either on the hour or on the half hour.[19][20] A dynamicdemand.co.uk/grid - Real-time frequency meter for power generation in the United Kingdom is available online. Smaller power systems may not maintain frequency with the same degree of accuracy.

    Frequency and load
    The primary reason for accurate frequency control is to allow the flow of alternating current power from multiple generators through the network to be controlled. The trend in system frequency is a measure of mismatch between demand and generation, and so is a necessary parameter for load control in interconnected systems.
    Frequency of the system will vary as load and generation change. Increasing the mechanical input power to a synchronous generator will not greatly affect the system frequency but will produce more electric power from that unit. During a severe overload caused by tripping or failure of generators or transmission lines the power system frequency will decline, due to an imbalance of load versus generation. Loss of an interconnection, while exporting power (relative to system total generation) will cause system frequency to rise. AGC (automatic generation control) is used to maintain scheduled frequency and interchange power flows. Control systems in power plants detect changes in the network-wide frequency and adjust mechanical power input to generators back to their target frequency. This counteracting usually takes a few tens of seconds due to the large rotating masses involved. Temporary frequency changes are an unavoidable consequence of changing demand. Exceptional or rapidly changing mains frequency is often a sign that an electricity distribution network is operating near its capacity limits, dramatic examples of which can sometimes be observed shortly before major outages.
    Frequency protection relays on the power system network sense the decline of frequency and automatically initiate load shedding or tripping of interconnection lines, to preserve the operation of at least part of the network. Small frequency deviations (i.e.- 0.5 Hz on a 50 Hz or 60 Hz network) will result in automatic load shedding or other control actions to restore system frequency.
    Smaller power systems, not extensively interconnected with many generators and loads, will not maintain frequency with the same degree of accuracy. Where system frequency is not tightly regulated during heavy load periods, the system operators may allow system frequency to rise during periods of light load, to maintain a daily average frequency of acceptable accuracy.[21][22]

    Ted Langdell
    Secretary

------------------------------------------------------------------------------

  _______________________________________________
  Please trim posts to relevant info when replying!
  Send QuadList list posts to QuadList at quadvideotapegroup.com
  Your subscribe, unsubscribe and digest options are here:
  http://mail.quadvideotapegroup.com/mailman/listinfo/quadlist_quadvideotapegroup.com

------------------------------------------------------------------------------

  No virus found in this incoming message.
  Checked by AVG - www.avg.com 
  Version: 9.0.801 / Virus Database: 271.1.1/2803 - Release Date: 04/10/10 14:32:00
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://quadvideotapegroup.com/pipermail/quadlist_quadvideotapegroup.com/attachments/20100411/bf485c3b/attachment-0004.html>