this is in part inspired by the art of hugh stegman
This one’s probably been around the block a few times. I was initially kinda worried because the fins looked roughed up but after some unscientific testing to make sure I could blow through them and fit a cable tie down between the fins to ensure there was a good pathway, I went ahead and installed it, and it came up just fine with a perfectly good stack temperature…
NO EXCUSES ON DA BOWL
The old tube went soft pretty quick. Don’t they have pills for that now?
And here’s what that goes in, a Harris/GatesAir 25,000 watt FM transmitter.
To swap it, you release a hose clamp holding a big collet on the movable top plate of the cavity so you can slide that plate blocker/chimney up, then release the hose clamp holding it to the tube (bottom), slide it up then clamp it again out of the way. Then you can carefully disconnect the plate voltage supply cap and somersault the tube upside down above the socket and remove it. I wish I’d taken a video of how bizarre this all looks.
Cooling air is forced both through holes in the socket and out of the cavity through the tube’s plate cooler after entering from the blower duct.
The two big fat orange wires – GatesAir / Gates / Harris Broadcast really likes that fat orange wire – are the filament supply, 10vdc Max at 150 amps. The HV, ~9500vdc at about 3 amps and change, comes in on a piece of RG-213 coax from this off board power supply.
A little dust but not too bad. The dust seemed to really like gathering on anything live with plate voltage. Eww. A more through cleaning will occur soon.
The QEI Model 691 FM modulation monitor!
It always makes me think of Pokey The Penguin comics.
Please feel free to use this photograph to torture graphic designers.
Sorry about the stray marks, I’ve been asked to respect the secret identity of my client. You’re not cleared for that. Fnord!
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…)
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.
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.
Then, hopefully, the power will stop being quite so…….. hungry for electronic snacks……
I find the following amazing:
Things you can buy locally in South Florida without waiting a week for shipping!
- Three phase 240V 2 horsepower rated variable frequency drive controllers (albeit at Grainger’s ~250% markup)
- Excessively overpriced fuses
Things you cannot buy locally in South Florida without waiting for shipping:
- Fuse holders
- Single phase variable frequency drive controllers (thankfully the machine I’m working on has 3 phase available)
- Anything that has to be delivered via UPS
- Fine stranded 16 gauge electrical wire (as opposed to the thick stranded THHN type stuff you’d run through conduits in a wall)
I had a fun time calling around this morning to find this out– Grainger only has two locations left around here, and even the sales lady on the phone was surprised by this. She was used to South Florida having a ton of them a few years back. I first learned of the Richmond Heights one having closed up shop when my last brush with high energy explosion happened… Luckily the one remaining location happened to have a VFD in stock I could use. Phew.
Grainger were the only ones who would be able to get the fuse holder here next day because they had them in a warehouse in Orlando (they also have their own trucks, so I’m confident it didn’t get melted down in Hialeah in the UPS warehouse fire). They had TWO in stock, dashing my plans to get three matching ones for the 3-phase VFD— oh well, different fuse holders but same fuses, whatever works for now. A 3 pole fuse holder would have had to ride the slow boat from China, just like if I’d wanted three of the single pole ones.
What bugs me is I USED to have the exact fuse holders I would have needed but threw them out last year, trying to reduce the size of my collection of parts I thought would be easy to buy again if needed.
Anyway, here’s the beautiful mess that inspired me to get very mad this morning while standing in front of a voltageless robot.
The problem: VFD controller smoked out. I didn’t take any pictures of the outside of the controller for it looked unremarkable save the “MOFF” error flashing. It looked like “ПOFF” due to the limitation of it having only a 7-segment readout, more rambling on that later. It might as well have said “F.OFF” though. The error meant it wasn’t getting sufficient voltage on the internal DC buss.
A quick primer on how VFD drives work:
I’ve seen similar modules in several VFD drive products. They contain multiple transistors and diodes coupled thermally (but not electrically) to a backing plate for heatsinking purposes. To avoid undue stress to the semiconductor junctions, they are filled with a curious sort of…. snot.
Sorry if I’m grossing you out, but touch it sometime, it’s really reminiscent of a sticky booger.
A similar product to that is Raychem’s “GelGuard” which I’ve seen used in outdoor telephone connectors. Very weird stuff.
Here is a diagram of the EasyPIM, borrowed off the Infineon website.
The obliterated parts are the rectifier diodes. Even though only four of the six were used in circuit due to this being a single phase drive, the remaining two were blasted to smithereens by excessive reverse voltage. The IGBTs at left (right in the diagram) that control the outputs look pristine and would probably even test good. Sorry, too lazy to whip out the ESR meter. (Does that even work on high voltage IGBTs?)
The CPU block in the above diagram is the timekeeper of the operation. It reads in whatever form of commands the unit is set to accept as to which direction and speed to run the motor. It also monitors several analog values throughout the unit – voltages, current levels, and temperatures – and can adjust its operation to protect itself and the motor if necessary by throttling back the amount of power it sends to the motor or shutting down if necessary. In this case, it was successfully detecting the lack of high voltage DC to run the drive and just wouldn’t do nuffin’.
Now if the damage had been confined to the module – that’s actually a standard part from Infineon and could probably just be ordered, buuuut—-
Yeah, this let it all right. It almost looks like the conformal coating tried to contain the Magic Smoke, and maybe even flashed over? The two line fuses for the drive were blown so something fun must have happened on the board itself. If the rectifier had just failed short, I would have expected ONE of the two to have gone, not both simultaneously. Flash to ground probably got the other one.
The client has been having a drive blow up every three months or so!! I’m going to retrofit the machine for him with some BIG HONKIN’ SURGE PROTECTION. After his first VFD blowout he called in Florida Plunder & Loot who did *something* to adjust his line voltage, but it’s still mega nasty. I’ll put the scope across it before installing the new drive and likely cringe so hard my face freezes that way for life.
Amazingly the drive still powered up, scrolled “HELLO” before going to “MOFF”, and I was able to get all the settings from it via the front panel user interface. See the small transformer at top left on the board? I suspect there’s a separate switcher power supply just for the CPU and logic that allowed for this even though the HVDC system was blown to bits.
And herein is another bit of rambling: The user interface on VFDs, for the most part, royally sucks. You’re presented with a menu system on the front panel which gives you anywhere from about a dozen to *HUNDREDS* of parameters, identified only by number. You have to break open the manual and go through dozens if not hundreds of pages of crap if your setup is in any way complicated. Fortunately THIS ONE IS NOT. This one was simply being driven by a +24vdc trigger to turn the motor on, and 0-10 volts DC to control the frequency between 0 and 60 hz. But still— Nice features I’ve seen in some units: Danfoss and Cutler-Hammer VFDs have a small control module that speaks plain English to you. Some other controllers (I’m unsure what brands off the top of my head) save the parameters to a small serial EEPROM or even an industry standard memory card, so if your drive does— this— you just swap the card into the new one and you’re ready to spin again.
An important word on the “Death Caps”:
THIS NAME IS NOT UNDESERVED
The capacitors inside a VFD drive will retain potentially lethal voltages FOR A VERY LONG TIME after power off. Even if they are discharged, they may exhibit a peculiar self-recharging phenomena where a stored charge in the electrolyte partially recharges the cap to dangerous levels again. Always discharge caps and test before touching! On a small self contained drive you cannot get in contact with the caps without disassembling the unit; however, I’m aware of there being larger units where the DC section is a separate unit and those can probably really get you. TEST FIRST. Also, if you are storing a spare unit, be sure to check the manufacturer’s directions on maintaining the capacitors!! Most say to power the drive up every year or so to keep the capacitors “formed”. If you suddenly connect power to a drive that’s been stored too long, EXPLOSIVE capacitor failure may occur. If you’ve got one that’s been sitting, consult the manufacturer’s directions for reforming. If unsure, use a Variac to slowly bring the voltage up, or put a small incandescent light bulb in series to limit the current. (The drive should draw almost nothing if it’s just powered up and not doing anything.)
Every time I start messing around thinking I want to make business cards for myself, THIS KIND OF THING HAPPENS
Q. What do you call a system of government in which one person is granted power to make immediate and sweeping changes that adversely affect life, business, travel, and well-being for large groups of its population?
A. A dictatorship.
While the ability for a U.S. president to issue executive orders bypassing the normal legislative processes has existed for a very long time, it has never before been used by a President to play fascist dictator…. Until now.
This capability needs to be reviewed and amended right the fuck now— unfortunately, with the latest Executive Order as of today, it’s possible there will be nobody left to do this.
Now I’m guessing this is also a death sentence to the EPA, effectively, turning its responsibilities over to the states. Get ready to have Florida’s water resources entirely managed by Big Sugar’s paid cronies with no oversight.
You might want to keep a few cases of bottled water in the closet.
– – – – – – –
COMPREHENSIVE PLAN FOR REORGANIZING THE EXECUTIVE BRANCH
By the authority vested in me as President by the Constitution and the laws of the United States of America, it is hereby ordered as follows:
Section 1. Purpose. This order is intended to improve the efficiency, effectiveness, and accountability of the executive branch by directing the Director of the Office of Management and Budget (Director) to propose a plan to reorganize governmental functions and eliminate unnecessary agencies (as defined in section 551(1) of title 5, United States Code), components of agencies, and agency programs.
Sec. 2. Proposed Plan to Improve the Efficiency, Effectiveness, and Accountability of Federal Agencies, Including, as Appropriate, to Eliminate or Reorganize Unnecessary or Redundant Federal Agencies. (a) Within 180 days of the date of this order, the head of each agency shall submit to the Director a proposed plan to reorganize the agency, if appropriate, in order to improve the efficiency, effectiveness, and accountability of that agency.
(b) The Director shall publish a notice in the Federal Register inviting the public to suggest improvements in the organization and functioning of the executive branch and shall consider the suggestions when formulating the proposed plan described in subsection (c) of this section.
(c) Within 180 days after the closing date for the submission of suggestions pursuant to subsection (b) of this section, the Director shall submit to the President a proposed plan to reorganize the executive branch in order to improve the efficiency, effectiveness, and accountability of agencies. The proposed plan shall include, as appropriate, recommendations to eliminate unnecessary agencies, components of agencies, and agency programs, and to merge functions. The proposed plan shall include recommendations for any legislation or administrative measures necessary to achieve the proposed reorganization.
(d) In developing the proposed plan described in subsection (c) of this section, the Director shall consider, in addition to any other relevant factors:
(i) whether some or all of the functions of an agency, a component, or a program are appropriate for the Federal Government or would be better left to State or local governments or to the private sector through free enterprise;
(ii) whether some or all of the functions of an agency, a component, or a program are redundant, including with those of another agency, component, or program;
(iii) whether certain administrative capabilities necessary for operating an agency, a component, or a program are redundant with those of another agency, component, or program;
(iv) whether the costs of continuing to operate an agency, a component, or a program are justified by the public benefits it provides; and
(v) the costs of shutting down or merging agencies, components, or programs, including the costs of addressing the equities of affected agency staff.
(e) In developing the proposed plan described in subsection (c) of this section, the Director shall consult with the head of each agency and, consistent with applicable law, with persons or entities outside the Federal Government with relevant expertise in organizational structure and management.
Sec. 3. General Provisions. (a) Nothing in this order shall be construed to impair or otherwise affect:
(i) the authority granted by law to an executive department or agency, or the head thereof; or
(ii) the functions of the Director relating to budgetary, administrative, or legislative proposals.
(b) This order shall be implemented consistent with applicable law and subject to the availability of appropriations.
(c) This order is not intended to, and does not, create any right or benefit, substantive or procedural, enforceable at law or in equity by any party against the United States, its departments, agencies, or entities, its officers, employees, or agents, or any other person.
DONALD J. TRUMP
THE WHITE HOUSE,
March 13, 2017.