Important Generac warning

Do not buy a Generac anything, but more importantly, don’t buy one of their automatic transfer switches. It will only work with a Generac generator. Surprise, beeyotch!!

This is a shitpost, I’ll elaborate later. See note inside interface box:

Boku no Hero Alternating Current

I misread the label on this generator as “Allmight” and now I can’t unsee that.

Proposition 65-G warning— Caution: This shitpost generates chemicals known by the State of California to cause groaning.

Go ahead, change the oil. I dare you.

This hilarious oversight found on an Allmand Maxi-Power 25 generator. The engine is a small turbodiesel utility engine made by Isuzu. The whole thing was assembled in Japan by Hokuetsu Industries….

… who hopefully sell a special bendy straw funnel.

Here’s the oil fill cap. The drain and filter are very easily accessible from the other side. But the filler… Oy!!

Above, the exhaust pipe.

Perhaps you can get in from the other side? …. Nope.

Look at that cute little tangerine sized turbocharger!

It seems to be like they could have added an access hatch above to make it easier, but yeah… Bring your Crazy Straws….

Guess I didn’t need a Fluke…

Now that’s a power glitch!! This voltage surge was long enough to get captured on an old school mechanical pen recorder.

Colorized for no good reason:

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(It’s physically impossible for the trace to reach the jackpot mark without blowing through the side of the meter movement. I was just being silly.)

Guess that explains why every time I’m looking at that transmitter the PA PLATE overload trip indicator is on showing that it had tripped and reset itself at some point. KABANG!!

Power Line Harmonics

So you may have seen me yelling about power line harmonics… here’s what I was looking at earlier this morning. This is the power at a facility I was doing some work at earlier today. The same power has laid waste to two variable frequency drive units and an Omron 24v power supply used to run a Programmable Logic Controller (PLC).

I used the FFT mode on my Tektronix DPO 2012 oscilloscope to better detail what’s going on. The yellow trace is the waveform coming in (you can see it’s not a perfect sine wave). The red trace is a plot of the frequency vs. amplitude after a Fourier transform. This same kind of plot may already be familiar to you: it’s displayed on many audio players and stereo systems as a spectrum analyzer visualization.

If this were perfect clean 60 hz power, I would have only the tall peak at the left which is 60 hz, then it would roll off to the baseline. What I got, however, is this (and a realization I accidentally set my scope’s clock 12 hours off *before* DST kicked in…)

Harmonic Horrors

 

The FOUR other peaks are the harmonics. Initially I thought I was looking at a second, third, fourth, and fifth harmonic, which would put the last one at 300 hz– reading this again though, it’s scaled 500 hz/division so what I’m looking at is the odd order harmonics at up to 540 hz– a NINTH harmonic.

Wow.

Now let’s look at that third harmonic, the most prominent. That one’s about 20dB down from the fundamental (the scale is 20dB per vertical division). That’s a voltage ratio of 0.1… so the third harmonic, if you were to isolate it, would be 12 volts at 180 hz. That just plain doesn’t belong!!!

A textbook square wave is the fundamental frequency plus all of its odd-order harmonics– 3, 5, 7, 9…. I suppose this makes sense, as if you smashed this AC waveform very very badly you would get a square wave.

Power line harmonics are an annoying effect of loads with a poor power factor. Want an example of a load with a poor power factor? You’re looking at it. The wall chargers for smartphones, power supplies for computers, and even LED, florescent, and compact florescent light bulbs are guilty due to the nature of their power supplies. Without getting too much into the theory I’ll say this: the way they work is that they draw power right at the peaks of the usual sine wave power. This is why the peaks in the above screenshot are getting smashed: that’s when EVERYTHING draws its juice.

Some *nicer* devices incorporate power factor correction circuitry to mitigate this. This usually takes the form of a low pass filter that acts on the amount of current drawn by the device, in an effort to keep it from just suddenly grabbing only the peak. Note that I say— “some”—

The harmonics tend to overstress everything by causing high currents to flow in wires, transformers, power supplies, etc– they are not only harsh to the equipment but they are a waste of energy.

And here, boy, do we ever have ’em.

The solution, ultimately, will probably be to have the local power company install a bank of capacitors for power factor correction on their poles.

Utillity PFC capacitors. Photo from a Cooper Power Systems press release.

Then, hopefully, the power will stop being quite so…….. hungry for electronic snacks……

Lift Station Controls or Pumping Poop With Pomp and Pizzazz

Ahhh nostalgia —-
My first introduction to control logic design was designing and building pump control panels with my grandfather. If you happen to find a relay logic panel labeled “C&K Electric”, that was us.

This isn’t one of ours, but it’s pretty similar in design and construction. We really preferred Furnas relays though, and whoever ran the line entrance to this thing needs to be dipped in…. *bwahahahaha* THE PIT!!!

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The Turd Alert.
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Schneider Electric contactors, eh, okay I guess. You heathens.
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Very nicely drawn diagram
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Pump alternator and turd alert silencer relay.

Here’s the basic operation: there are four float switches in the pit.

Switch 1: latch enable. Does nothing when switched on, but if a pump is latched on by its aux contact and it drops from low sewage level, it stops the pump(s). The alternator relay is also triggered at this point; it’s essentially a falling edge triggered gate. This changes up which pump will run next time so they take turns for wear leveling purposes.

Switch 2: start lead pump (as determined by alternator position). This will latch on until switch 1 opens.

Switch 3: Also start lag pump. This occurs when there’s too much flushin’ going on for one pump to handle it alone.

Switch 4: TURD ALERT!!! Condition BROWN! Sewage level is dangerously high; can occur due to pump failures, flooding, or a number of other very nasty things. While switch 4 is active, the red light comes on and an audible alarm sounds. This alarm can be silenced (will auto rearm as soon as the alarm condition clears).

On a side note– I recall the insides of those Diversified Electronics alternators being hilarious. It was like six tiny relays in a potted board and it invoked the obvious question of why not just use a spring loaded pawl mechanism like Furnas does?? Guardian Electric also made a version with a cam and ratchet; it was okay when new but the plastic cam was prone to degrading. Can’t win ’em all I guess.

Solar Safety: High Current Fault video

A common mistake I see some people make when designing a solar energy system is that they will parallel the outputs of the solar panels without using a combiner box that has fuses or breakers.

This works fine in the “yeah, the lights come on” sense, but if you should ever have a fault in one of the modules, you may very well experience a fire at the module that will spread to any other flammable materials nearby….. yes, that means your ROOF.

Note that while the solar panel’s encapsulant and backsheet self-extinguish and only exhibit a couple millimeters of flame spread, the sheet of paper I taped to it to simulate the flammable debris that *will* gather around your panels does not! 🙂

Flammable crap you will typically find around and on your panels includes oily soot from smoke/automobile exhaust, dried leaves, paper, bird nests… anything the wind or animals can bring in!

Under the hood: Morningstar SunSaver MPPT.

Buckin' Bronco

This is the Morningstar Sunsaver MPPT charge controller, capable of pumping 15 amps into a 12 or 24 volt battery system from an up to 75V input. It’s fairly simple, though the 6P6C jack can be used for Morningstar’s Modbus system or Remote Meter to add more control, programming, and monitoring capabilities. The unit is driven by a Microchip PIC18???* microcontroller.

A typical MPPT controller consists of a switching buck or buck-boost converter with the input connected to the solar panel array, and the output connected to the battery system. A microcontroller monitors the solar array voltage and current (and multiplies them to calculate the power) periodically, and adjusts the switching of the converter appropriately to keep the input side voltage at the solar array’s maximum power point, Vmp.

Inside the Morningstar Sunsaver MPPT, there is… a switching buck converter with a micro… etc. Here you go:

* The conformal coating stuck to the top of the chip made it difficult to read. Like the flavor of PIC matters? XD

Control/Logic Board

No fans or other active cooling are needed. The inductor is thermally coupled to the back of the housing, which is a tall metal fin attached to the heatsink/base. The switching transistors are, undoubtedly, potted somewhere in there. The potted construction is also used on the SunSaver PWM controllers.

Simple, elegant, but here’s the big question: WHY does it cost $250?! Rest assured, I’m scouring the market for some *good* low cost MPPT controllers. This is just a very good and not quite as low cost controller!

Under the hood: The Outback FM80

Warning: Engineering porn ahead. All images are clickable to view in full resolution.

The Outback Power FM80 solar charge controller is a high performance MPPT controller which converts a solar array’s output (up to 150VDC, 64 amps) down to charge a 12, 24, 36, 48, or 60 volt DC battery string using a high efficiency switching buck converter and an extremely flexible microprocessor control system. It is field programmable from the front panel and can be linked to other system components using Outback’s communication buss and the MATE controllers for system logging and remote control.

It is extremely well built, and solid as a rock.

More photos below…

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