relay logic

On Wednesday, 18 September 2019 18:31:28 UTC+1, bitrex wrote:

On 9/18/19 6:45 AM, Michael Terrell wrote:
On Wednesday, September 18, 2019 at 3:08:11 AM UTC-4, Piotr Wyderski wrote:
bitrex wrote:

Anyone remember that guy who used to post on one of the sci.electronics
groups several years ago who seemed like he was trying to control a
whole house and barn electrical system with relay logic?

What would it be a silly idea? You don't need high speed there and
relays are insanely immune to surges, especially when they are in a
stable state during the surge.

Best regards, Piotr

Relay control of lights and outlets in high end homes was common in the '60s and '70s. A load could have a local switch, be remote controlled or from a timer and all with low current 24VAC wiring. A single switch could turn on every light on the property, if needed. That could be connected to the dry output of an alarm panel for security. I knew one electrical contractor who installed and maintained them, when I was teaching people to install alarm wiring.


as I recall the system this guy was working on was more like a relay
computer, switching 120V loads, and the relays themselves were 120V coil
types inside of feedback-loops driven off the loads themselves.

Like hairball-logic built with line voltages

Reminds me of a 1970s commercial scale misting unit, all relay logic run at 240v. Yes, in a soaking wet zone. No inbuilt checks, redundancy, fuses, RCD, anything. And made of asbestos.


NT

 

On Wednesday, September 18, 2019 at 2:10:16 PM UTC-4, John Larkin wrote:

On Wed, 18 Sep 2019 10:13:21 -0700 (PDT),
bloggs.fredbloggs.fred@gmail.com wrote:

On Wednesday, September 11, 2019 at 11:24:08 PM UTC-4, jla...@highlandsniptechnology.com wrote:
I think this is right. It was a minor brain sprain, after the banana
bread and rum.

https://www.dropbox.com/s/r6vg4fmnnwgk96y/30_60_120_3relays.JPG?raw=1

Imagine designing an entire dial telephone system with relays.

What's wrong with just stacking all the secondaries in series and then picking off the selected voltage at the appropriate tap? Isn't that just two relays?
And 30-60-120 is a weird progression.

That wastes VAs by not using all the copper all the time.

30-60-90-120 is even better. I'm simulating alternators and there are
all sorts of alternators.

Is the VA a function of output voltage, as in the lower output voltage source has a higher VA rating than the higher voltage output source? That doesn't make any sense.

 

[John Larkin]

On Wed, 18 Sep 2019 15:28:36 -0700 (PDT),
bloggs.fredbloggs.fred@gmail.com wrote:

On Wednesday, September 18, 2019 at 2:10:16 PM UTC-4, John Larkin wrote:
On Wed, 18 Sep 2019 10:13:21 -0700 (PDT),
bloggs.fredbloggs.fred@gmail.com wrote:

On Wednesday, September 11, 2019 at 11:24:08 PM UTC-4, jla...@highlandsniptechnology.com wrote:
I think this is right. It was a minor brain sprain, after the banana
bread and rum.

https://www.dropbox.com/s/r6vg4fmnnwgk96y/30_60_120_3relays.JPG?raw=1

Imagine designing an entire dial telephone system with relays.

What's wrong with just stacking all the secondaries in series and then picking off the selected voltage at the appropriate tap? Isn't that just two relays?
And 30-60-120 is a weird progression.

That wastes VAs by not using all the copper all the time.

30-60-90-120 is even better. I'm simulating alternators and there are
all sorts of alternators.

Is the VA a function of output voltage, as in the lower output voltage source has a higher VA rating than the higher voltage output source? That doesn't make any sense.

Power loss in a wire goes as current squared.

If I had four identical windings stacked up, and could deliver, say,
120V at 1 amp when they are in series, that's 120 VA to the customer.
If it has 1 ohm per winding, the total secondary copper loss would be
4 watts. Voltage loss is 4 volts total out of 120.

If I use only one winding to get 120 VA at 30 volts, there would be 4
amps in that chunk of wire. 16 watts loss. Voltage loss is 4 out of
30.

If I used 4 windings in parallel to get 30 volts, I'm back to 4 watts
total loss. 1 volt lost.

A transformer is most efficient and economical if you use all that
expensive copper all the time in a balanced way.

My class D amps can theoretically output 600 watts each. I can buy a
kilowatt main power supply. The thing that limits the specs of a
channel, or of the whole box, is the size and cost of the output
transformers.

A few dollars worth of relays keeps the channel output at my 120 VA
spec on all voltage ranges.

 

On Wednesday, September 11, 2019 at 11:24:08 PM UTC-4, jla...@highlandsniptechnology.com wrote:

I think this is right. It was a minor brain sprain, after the banana
bread and rum.

https://www.dropbox.com/s/r6vg4fmnnwgk96y/30_60_120_3relays.JPG?raw=1

Imagine designing an entire dial telephone system with relays.

Yes. I've done something similar. When I first got out of college with a good dose of two courses in classical control theory I was hired in an engineering company that engineered and constructed various steel mill plants (e..g. coke oven, blast furnace and stove changing controls). Thinking I could put LaPlace transforms and open & closed loop response theory into practice, I was shocked to run into reality - everything was controlled by ladder logic. With a crash course in ladder logic in evenings and weekends, and leveraging designs from previous work, I was able to design the control logic for sequencing the stoves for a blast furnace. It consisted of two 8'x6' enclosures full is 'control relays' arranged horizontally one next to each other, estimating 50 relays/row and about 10-12 horizontal rows with panduit wireways between them. In addition to producing the schematics, I had to produce the wiring diagrams to be used in the shop for assembly, and then design the knife switch and light 'simulation panel." On what fun it was checking it out.
The next version of the control system was based on discrete logic, DEC 'K series' logic, which I designed and wire wrapped because the techs didn't know about wire wrapping till after I walked them through it.
Version 3 of the control system was based on a new technology called PLC's (Programmable logic controllers' which basically emulated ladder logic based on a intel 4004 and some ancillary discrete logic and I/O signal conditioning. the I/O was binary, no analog...yet. I needed to design some logic to make a decision based on the division of settings from two sets of 3-digit thumbwheels on a control panel. I ended up designing and implementing a divider in relay logic.
While not as complex as a phone switching system, the stove changing logic was very complex for its time. Now the same thing could be done with a PLC the size of a shoe box and the I/O rack in a 2'x3' enclosure.
A classmate of mine went to work for Bell Labs and ended up working on ESS3 and 4. For a look at a fascinating rotary switch which was the corner stone of the phone network switching, see: https://www.youtube.com/watch?v=xZePwin92cI
Designing that beast must have been a challenge, not to mention the ridiculously high reliability needed....Two of my prized publications in my library are from Bell Labs: Unix System Journal, Step-by-Step switch theory of operation.
J

 

[Piotr Wyderski]

John Larkin wrote:

If I had four identical windings stacked up, and could deliver, say,
120V at 1 amp when they are in series, that's 120 VA to the customer.
If it has 1 ohm per winding, the total secondary copper loss would be
4 watts. Voltage loss is 4 volts total out of 120.

Provided the windings are identical, which is kind of a brave
assumption. You need special windng techniques to achieve that.

A transformer is most efficient and economical if you use all that
expensive copper all the time in a balanced way.

The transformer yes, but the whole system -- not necessarily.

I have never seen a switcher with a bridge rectifier at the output.
A copper-wasting center-tapped full wave is the standard.

Best regards, Piotr

 

On Thu, 19 Sep 2019 09:22:10 +0200, Piotr Wyderski
<peter.pan@neverland.mil> wrote:

John Larkin wrote:

If I had four identical windings stacked up, and could deliver, say,
120V at 1 amp when they are in series, that's 120 VA to the customer.
If it has 1 ohm per winding, the total secondary copper loss would be
4 watts. Voltage loss is 4 volts total out of 120.

Provided the windings are identical, which is kind of a brave
assumption. You need special windng techniques to achieve that.

No, I need a specification and a normally-competant transformer
manufacturer. I have those.

Many commercial power transformers have dual primaries and dual
secondaries, spec'd to be used in series or in parallel. People who
wind power transformers don't randomize turns counts.

A transformer is most efficient and economical if you use all that
expensive copper all the time in a balanced way.

The transformer yes, but the whole system -- not necessarily.

Adding gratituous transformer loss doesn't help.

I have never seen a switcher with a bridge rectifier at the output.
A copper-wasting center-tapped full wave is the standard.

Bridge rectifier?

Not in my box. But my simulated alternator output will often drive a
bridge rectifier+capacitor, with a shunt regulator somewhere.

Best regards, Piotr

 

[Tauno Voipio]

On 12.9.19 06:23, jlarkin@highlandsniptechnology.com wrote:

I think this is right. It was a minor brain sprain, after the banana
bread and rum.

https://www.dropbox.com/s/r6vg4fmnnwgk96y/30_60_120_3relays.JPG?raw=1

Imagine designing an entire dial telephone system with relays.

Here you have some:

<http://web.cecs.pdx.edu/~harry/Relay/>

--

-TV

 

[Piotr Wyderski]

jlarkin@highlandsniptechnology.com wrote:

Many commercial power transformers have dual primaries and dual
secondaries, spec'd to be used in series or in parallel. People who
wind power transformers don't randomize turns counts.

Turn count is one thing, wire length is another. Much harder to make
identical. I'd use 4 twisted wires and wind the secondary(-ies) with
that rope, then untwist the endings.

Best regards, Piotr

 

On Thu, 19 Sep 2019 17:30:04 +0200, Piotr Wyderski
<peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

Many commercial power transformers have dual primaries and dual
secondaries, spec'd to be used in series or in parallel. People who
wind power transformers don't randomize turns counts.

Turn count is one thing, wire length is another. Much harder to make
identical. I'd use 4 twisted wires and wind the secondary(-ies) with
that rope, then untwist the endings.

Best regards, Piotr

My transformer will resemble this one

https://www.digikey.com/products/en?keywords=1182l30

but I'll have one primary and four secondaries.

That Hammond part works fine with any combination of connections. The
voltage imbalance between windings is parts per million.

 

[John Larkin]

On Thu, 19 Sep 2019 08:42:02 -0700, jlarkin@highlandsniptechnology.com
wrote:

On Thu, 19 Sep 2019 17:30:04 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

jlarkin@highlandsniptechnology.com wrote:

Many commercial power transformers have dual primaries and dual
secondaries, spec'd to be used in series or in parallel. People who
wind power transformers don't randomize turns counts.

Turn count is one thing, wire length is another. Much harder to make
identical. I'd use 4 twisted wires and wind the secondary(-ies) with
that rope, then untwist the endings.

Best regards, Piotr

My transformer will resemble this one

https://www.digikey.com/products/en?keywords=1182l30

but I'll have one primary and four secondaries.

That Hammond part works fine with any combination of connections. The
voltage imbalance between windings is parts per million.

Specifically, about 5 PPM at 400 Hz. Hard to measure.