Instrument Technician vs Electrician - NWS (language)

[Fred W]

250VDC? Child's play.

How about messing around with 120KV (yes, that's killer-volts DC) we use for generating Xrays. Even our little 35KW 127 Mhz RF transmitters (they still use vacuum tubes) have 15-20 KV DC plate voltages.

Try letting the smoke outta one of them...

 

[Redfish Hunter]

A good engineer ...

Now that right there is an oxymoron. One time we got this drawing from the engineer on a modification we were doing for the precipitator control system at the coal generating plant. The standard was to mark the control wires being removed in green and the wiring that would stay in red. The engineer had put some scribblings down on the drawing in pencil. We went back to the engineer and I asked him if those lines in pencil where the grey areas and if we should just make it up as we go along. For some reason the engineer did not see the humour in that. My fellow instrument tech was pissing himself laughing.

Actually, and I know they are rare as hen's teeth, there are a few. I was privileged to work with two very good, very useful engineers once while building a new unit from the ground up. One of them rides a BMW R1150R and the other rides an '09 FJR. Of course, at the time the FJR guy was riding a V-Strom, he upgraded to the FJR later. When you find one, they seldom stay long. Even other engineers recognize the difference and they soon get promoted and move off to bigger and better things. Finding a "Good Engineer" is a lot like finding the Tooth Fairy or a Unicorn. It happens so seldom that no one believes you when you try to explain it.

Letting the smoke out is always a bad sign. I've let the smoke out of a few minor components and once watched the smoke leak from a brand new 13,800 volt switch. That was quite a boom.

 

[beemerdons]

Oh how I just love Dog Pile Fridays on our Fine FJR Forum, especially since this thread has derailed over to Engineers. I have a thousand Engineer jokes, really eh!

"Three men were sentenced to be executed by guillotine; a priest, a Muslim, and an engineer.

First was the priest and he asked that he face upwards so he could look at Heaven and his Creator. his wish was granted and the blade fell, but stopped 1/2 inch from his neck. the executioner said since the guillotine spared him, so was his life and he was allowed to leave.

Next was the Muslim and he asked that he also be allowed to face upwards to look to Allah before his death. again the guillotine stopped just short and his life was spared as well.

The engineer was last and he too asked to face upwards given what happened with the first two. as he lay there, he looked up at the mechanism and said, "Aha, i see the problem!".

 

[yamafitter]

250VDC? Child's play.
How about messing around with 120KV (yes, that's killer-volts DC) we use for generating Xrays. Even our little 35KW 127 Mhz RF transmitters (they still use vacuum tubes) have 15-20 KV DC plate voltages.

Try letting the smoke outta one of them...

As you know Fred is not the volts that get you, it's the amps. I once saw a 4KV 3000 Amp service breaker get racked off the bus while it was still closed. Could not see the smoke for the arc flash. My heart was still pounding 30 minutes after it happened. Needed a new pair of shorts too.

 

[ionbeam]

250VDC? Child's play.
How about messing around with 120KV (yes, that's killer-volts DC) we use for generating Xrays. Even our little 35KW 127 Mhz RF transmitters (they still use vacuum tubes) have 15-20 KV DC plate voltages.

Try letting the smoke outta one of them...

Indeed! Surprisingly, I'm still alive after 20 years building ion implantation equipment (see my Forum name...). These machines operate from 10KV to 250KV DC and 1,000,000 volts AC (RF) to 10,000,000 volts AC (RF). When something went wrong we didn't just blow a fuse, have a small flame and a thunderous boom, we took out the entire power grid for the local city (Danvers, MA). We did this often enough that the city told us that it had to stop and the next time we blew the grid they were going to charge us for the repair. We hired a couple of guys from the power company to isolate our business from the main power grid. During the construction there was an accident that blew two workers out of the manhole and onto the lawn. One was killed and the other had major burns. Being a sparkie can be dangerous work.

I'm currently (pun?) building laser and flash lamp power supplies that run up to 40KV. And yes, some of these still use vacuum tubes. You definitely don't want to have a bad day at work when playing with this kind of voltage.

 

[Fred W]

250VDC? Child's play.
How about messing around with 120KV (yes, that's killer-volts DC) we use for generating Xrays. Even our little 35KW 127 Mhz RF transmitters (they still use vacuum tubes) have 15-20 KV DC plate voltages.

Try letting the smoke outta one of them...

As you know Fred is not the volts that get you, it's the amps. I once saw a 4KV 3000 Amp service breaker get racked off the bus while it was still closed. Could not see the smoke for the arc flash. My heart was still pounding 30 minutes after it happened. Needed a new pair of shorts too.

True dat. But when you start out with 120KV the least bit of conductivity gets you a whole bunch o' them amps.

When you're hookin' up an Xray tube the contacts are at the end of these 6" insulators that go down into insulated wells in the tube. The cable ends look like this:

And here's a cutaway of a typical (old school) Xray tube that shows the wells that the cable ends go into.

By the way, the positive and negative KV were carried on two separate cables at opposite ends of the tube as you can see in the above picture.

You have to completely fill the air gap between the male and female connector halves with clean dielectric grease. If you have too many air bubble voids or any contamination in the grease, when you crank up the KV to make an exposure... *whack*

The smoke would get let out of the HV Power Supply pretty often in that circumstance.

In some older CT scanners those HV cables had to flex back and forth in a giant cable takeup while the tube was rotating around the patient. After a while they would chafe or start to crack and there would sometimes be a fairly spectacular (and often destructive) lightning show. Of course this was inside the fiberglass covers arcing to the grounded frame, not near the patient. Now they use mega slip-rings (instead of flexing the cables) so they can get constant rotation.

I don't actually work with any ionizing radiation any more. I've moved on to even more dangerous and much more complicated stuff.

 

[ionbeam]

One of the cool things about working with high voltage like this is you don't even have to touch it to get a life threatening shock, all you have to do is be near by and it will reach out and touch you.

It's interesting working at a job where you have extreme voltages, have to wear a radiation badge and have it checked weekly, bi-weekly provide a 'sample' to be tested for toxic chemicals that are used in the ion source and have to work in an environment where there are large, heavy, fast moving potentially body crushing mechanical parts.

 

[wnyfjr]

In another life, I was a broadcast 'engineer' (I know that may not qualify as a real engineer, but that's what we were called) and spent many nights on a mountain or out in the woods somewhere working on broadcast trasnmitters (100kW) with capacitors the size of 5-gallon buckets. There were very strict protocols for opening those cabinets up and using the grounding rod to discharge those caps before doing anything inside the cabinet. I worked on at least two transmitters that were real killers (had killed a previous engineer who hadn't followed protocols). That was never my favorite part of that job. I much preferred the free trip to Jamaica, or the free meals at local restaurants, free concerts, t-shirts, etc! You folks who fart around with voltage/amperage like this, you're not quite right...and I mean that in the NICEST way!

 

[gixxerjasen]

Now I'm terrified to get an x-ray. Thanks!

I love the rivalries. I spent a summer working for my wife's step father doing HVAC installation. One day he was bitching about the stupid engineers that draw up the plans. I rolled my eyes because he wasn't a particularly bright guy, and what we were doing wasn't even a little bit difficult. I figured he was likely the idiot and not the engineer.

Couple weeks later I'm doing a run and the idiot sprinkler installers had run their pipe right where my duct was designed to go. Flip through the plans and low and behold, it was the guy drawing up the plans that was the idiot.

 

[Powerman]

"I've even rebuilt ledoux bell flow transmitters but now I'm really dating myself." Wow, haven't seen any of those for a while!

I rebuilt a VSD last year that got drowned, Leaking pipe inside some ductwork ran into the drive, idiots.

Ask Intech about the wonderful power plant engineer that adjusted a pneumatic drive with a crowbar.

My wife was just sure I was going to jail because I snapped and beat the crap out of that engineer!

 

[garauld]

Oh well - here goes - pile away... I spent most of my professional engineering career doing projects in coal and hydro powerplants... but, I can weld...

 

[Redfish Hunter]

Nevermind. I really messed up the whole post and could not fix it...

 

[dcarver]

Nevermind. I really messed up the whole post and could not fix it...

And THAT is why you're a tech, not Sys Admin!

 

[yamafitter]

Nevermind. I really messed up the whole post and could not fix it...

And THAT is why you're a tech, not Sys Admin!

A quality Instrument Tech is never that blunt about taking the blame. When an Instrument Tech messes up we usually use an explanation with so much technobabble no one knows what we are talking about. Management usually just nod their head in agreement and then go and yell at some fitter who does not have this skill set and can't talk their way out of it.

 

[ionbeam]

...When an Instrument Tech messes up we usually use an explanation with so much technobabble no one knows what we are talking about. Management usually just nod their head in agreement...

W.C. Fields - "If you can't dazzle them with brilliance, baffle them with ********."

 

[gixxerjasen]

And THAT is why you're a tech, not Sys Admin!

Dang....I wasn't even going to go there.

Of course, every SysAdmin has a punch down tool so he can fix what the electrician didn't do right.

 

[wnyfjr]

...When an Instrument Tech messes up we usually use an explanation with so much technobabble no one knows what we are talking about. Management usually just nod their head in agreement...

W.C. Fields - "If you can't dazzle them with brilliance, baffle them with ********."

I live by those wise words!