In the US, I have seen line voltage as low as 70VAC and as high as 145VAC. That's what I design to. The power companies say different, but my meters don't lie.
-----Original Message----- From: time-nuts [mailto:[email protected]] On Behalf Of Jeremy Nichols Sent: Tuesday, December 19, 2017 9:20 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] External cooling fans - source I put a small external fan on my 5370B, which keeps the heat sink at a reasonable low temperature (Time-Nut content) -but- (Nixon segué) the power company here also runs the voltage all the way up to the limit (126VAC) because "many of our [rural, like me] customers are all-electric and the load tends to pull the voltage down during times of peak use." The voltage got so high I finally put a recorder on it and walked the results into their office. In response, they attached their recorder to my connection and ran it for a couple of weeks before agreeing with me. Then they reluctantly turned the transformer down a notch so we stay below 126VAC now. Jeremy On Tue, Dec 19, 2017 at 5:44 AM Bob kb8tq <[email protected]> wrote: > Hi > > Yes, this *is* a bit off topic. Sorry about that … I’m sure it’ll > never / ever happen again :) …. ummm …. today …. > > The voltage that supply feeds are set to is as much a public relations > issue as a technical one. People would routinely complain “the lights > are to dim”. > Voltage > gets bumped up. Complaints drop off. Eventually you are right at (or > as you observe marginally above) the max limits. Since the power > company is paid by the watt, the added power usage (if any) is not a > big deal. The call outs for checks > *are* a big > deal to them ….. complaints impact the metrics by which they are judged …. > > Bob > > > On Dec 19, 2017, at 12:48 AM, Dr. David Kirkby < > [email protected]> wrote: > > > > On 18 December 2017 at 23:11, Charles Steinmetz > > <[email protected]> > > wrote: > > > >> From time to time, the subject of external cooling fans comes up -- > >> for example, in discussions of the HP 5370A/B with their steaming > >> hot heatsinks. I have several times recommended very quiet, all-metal, 4" > desk > >> fans as ideal for the job, but have not been able to suggest a source. > >> > > > > For what it is worth, my 5370B run very hot, which forced me to > > check my mains voltage as I knew every time I had done a quick > > measurement, the voltage was above 230 V. So for a few days I logged > > the voltage, and > found > > it was consistently high. The maximum permitted here in the UK is > > 253 V, but I measured mine at 255.x volts. It was the heat of the > > 5370B that forced me to contact the electricity supply company (UK > > Power Networks), who logged the voltage for 4 days. I have a 3-phase > > supply here, which is unusual for a domestic property, but each of > > the 3 phases was > consistently > > high. I managed to get the supply company to reduce the voltage by 5%. > That > > made a *significant* difference in the heatsink temperature of the > > 5370B, and a significant difference to to the exhaust temperature of > > my HP 70000 series system. > > > > I'm not saying an extra fan is not a good idea, but it is certainly > > worth ensuring the mains voltage is not too high. I was told by UK > > Power > Networks > > that they aim for 245-250 V in rural areas - this is despite the UK > > is supposed to be 230 -6%/+10%. On equipment with linear power > > supplies, a > few > > extra volts can lead to a significant increase in the amount of heat > > the regulators produce. 10% extra voltage does *not* equate to 10% > > extra > power > > dissipation, but considerably more. > > > > I found quite a reluctance on the part of the UK Power Networks to > > reduce the voltage. Even though it was was on average more than 5% > > high, the technical manager who took ownership of the problem only > > wanted to reduce the voltage by 2.5%, despite they could easily > > reduce it 5%. Luckily, > when > > the engineers came to adjust the supply voltage, (which they do by > changing > > the taps on the 11 kV primary), I managed to convince them that > > there > were > > very few properties on the transformer, and the furthest was an old > couple > > that used very little electricity. So they did reduce it 5%, which > > is the maximum they could. But they warned me that if there were > > complaints of > low > > voltage, they would have to increase it 2.5%. Luckily for me, nobody > > locally noticed the reduction in mains voltage, and it is still on > average > > over 230 V. > > > > It would be interesting to know how low the AC input can go on a > > 5370B before the regulators fail to regulate. Given they are the > > sort of instrument one might want to run for long periods, running > > one on a UPS, with a transformer to reduce the output of the UPS, > > might not be such a > bad > > idea. > > > > > >> Charles > >> > > > > Dave > > _______________________________________________ > > time-nuts mailing list -- [email protected] To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Sent from my iPad 4. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
