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Always a 'fun' day when you get to put on the extra layers

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BreeStephany

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May 19, 2012
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Oregon
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Came in with a coworker after production hours to troubleshoot the 15kVDC 'high side' of a problematic RF generator and got to sweat my **** off in an arc flash suit.

For those of you in the know about proper arc flash PPE, yes, I know I have my balaclava pulled down... it was hot as hell and my goggles fogged, so stopped, got to a safe state and had my coworker power down the machine, verified it was de-energized and stepped away to wipe my goggles out, kept the balaclava down until I was ready to go back at it and my coworker snapped a few photos in the time between.

Determined that the newly installed oscillator is failing to generate RF below full power, so will need to replace the oscillator, burn it in and hopefully get this old ******* of a machine up and running soon.

Its a bit of a crazy machine. 480VAC 3ph 60hz in, transformed to ~7500VAC 3ph 60hz, input voltage to the transformer is changed via SCRs based on the "power" rheostat to control power output. The secondary of the HV tranformer is rectified to DC and stepped up to 15kVDC and the oscillator pulses the DC signal at 4.2Mhz, stored in a capacitor bank / "tank" which then has the ground circuit for the inductive heating coil controlled by an SSR that turns on and off approximately 400~800 times per minute based on the operating speed of the machine so that the inductive field is not present when the machine is inserting parts.
 
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BreeStephany

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May 19, 2012
Messages
854
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Oregon
whateg01 said:
Working on radar CRT always scared the **** out of me. I would check that everything was discharged multiple times before I'd stick my hand anywhere.
Click to expand...
In most cases, this is the case... lock out, ensure incoming power is de-energized and discharge everything on the high voltage side... but I had to verify correct and consistent voltage on the secondary of the HV transformer and verify proper voltage at the rectifier, so I had to place probes live. 25kV hot work gloves, full arc flash gear and had a 25kV mat between myself and the ground.
 
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whateg01

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Joined
Mar 13, 2006
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Location
doo dah, kansas, usa
BreeStephany said:
In most cases, this is the case... lock out, ensure incoming power is de-energized and discharge everything on the high voltage side... but I had to verify correct and consistent voltage on the secondary of the HV transformer and verify proper voltage at the rectifier, so I had to place probes live. 25kV hot work gloves, full arc flash gear and had a 25kV mat between myself and the ground.
Click to expand...
Oh, I get it. Sometimes you have to troubleshoot a live circuit. I think the only time I ever had to was in ET A-school. I'm ok with that. I remember all the checks beforehand. Blowing up the rubber gloves to check for pin holes.
 
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Old Man Roger

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Apr 6, 2017
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17,856
Location
Palm Coast Florida
BreeStephany said:
1000015192.jpg1000015193.jpg
Came in with a coworker after production hours to troubleshoot the 15kVDC 'high side' of a problematic RF generator and got to sweat my **** off in an arc flash suit.

For those of you in the know about proper arc flash PPE, yes, I know I have my balaclava pulled down... it was hot as hell and my goggles fogged, so stopped, got to a safe state and had my coworker power down the machine, verified it was de-energized and stepped away to wipe my goggles out, kept the balaclava down until I was ready to go back at it and my coworker snapped a few photos in the time between.

Determined that the newly installed oscillator is failing to generate RF below full power, so will need to replace the oscillator, burn it in and hopefully get this old ******* of a machine up and running soon.

Its a bit of a crazy machine. 480VAC 3ph 60hz in, transformed to ~7500VAC 3ph 60hz, input voltage to the transformer is changed via SCRs based on the "power" rheostat to control power output. The secondary of the HV tranformer is rectified to DC and stepped up to 15kVDC and the oscillator pulses the DC signal at 4.2Mhz, stored in a capacitor bank / "tank" which then has the ground circuit for the inductive heating coil controlled by an SSR that turns on and off approximately 400~800 times per minute based on the operating speed of the machine so that the inductive field is not present when the machine is inserting parts.
Click to expand...
Bree, what language are you speaking? It looks just like English but I didn’t understand half of it.lol
 
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Debcrow

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May 14, 2019
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Location
New Mexico
Old Man Roger said:
Bree, what language are you speaking? It looks just like English but I didn’t understand half of it.lol
Click to expand...
He forgot to put in the 'SOB' in his description!

"Reach out and Touch Someone" should have been used for high voltage workers, not by AT&T. :)
As anyone who has opened high KV connections can tell you about extended arc's.
 
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Old Man Roger

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Palm Coast Florida
cvairwerks said:
High voltage electrical grab your **** and kill you.....🙃
Click to expand...

Debcrow said:
He forgot to put in the 'SOB' in his description!

"Reach out and Touch Someone" should have been used for high voltage workers, not by AT&T. :)
As anyone whose has opened high KV connections can tell you about extended arc's.
Click to expand...
Garage journal translators.lol Thanks guys.:beer:
 
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Snapped-off

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Joined
Feb 22, 2012
Messages
4,815
Location
Indiana
We throw the 40 cal suit on for our 35kv stuff.

The 480v 3,000-5,000 amp stuff gets 8 or 25, depending on what's required. Panel covers are always in place though, no need for us to do live interior work.
 
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matt_i

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Joined
Mar 14, 2008
Messages
10,752
Location
SE Michigan
I had a 40cal on a week ago, troubleshooting lack of power to find the circuit breaker for the 1200A bus tripped in the indoor substation room.

They are more fun in winter months ;)
 
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Codyboy

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Jan 31, 2019
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Location
S.E. TEXAS
Screw that , it's no fun at all.

We had to wear that **** when working on 480

We could work 35kv (hot stick only no gloves) and work 12kv with gloves from a bucket and only had to wear the normal FR shirt and pants.

The reason for all the dress up for 480 was the available fault current it could generate during a fault is my understanding.

I have no idea what Calorie rating our gear was as it was what ever was issued.
The worst part was the balaclava and the special hooded helmet. I hated that thing because for a shortnecked guy it was impossible to adjust and would ride on my shoulders .
I guess the main worst part was doing all that in Houstons 100* summers. F all that.
 
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