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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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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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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.
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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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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.
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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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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.
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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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Old Man Roger said:
Bree, what language are you speaking? It looks just like English but I didn’t understand half of it.lol
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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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cvairwerks said:
High voltage electrical grab your **** and kill you.....🙃
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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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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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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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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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BreeStephany

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wyliesdiesels said:
ok so what does this machine do or what is it for?
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It is a simple RF generator that produces a low amperage, high voltage radio frequency signal at around approximately 4.2Mhz. The signal energy is stored in a "tank circuit" capacitor bank, that when grounded, induces a signal across a copper coil for approximately 6~8 milliseconds once small metal parts have been inserted into ceramic holders in the coil and then de-energizes befofe parts are eiected. Due to the high frequency, the high voltage is induced across the metal parts approximately 5000~6000 times in the 6~8 millisecond run time, causing the metal parts to rapid heat to a glowing state before being ejected through a quench tank and onto a conveyor.

The handler which moves the metal parts runs at approximately 400~800 rpm, which allows up to approximately 1600 parts per minute to be precisely heat threated with controlled penetration, since we are able to fine tune the RF field to concentrate the center of its field at the point in the metal parts at which we want to concentrate the heat treatment.

The parts are induction treated to make them very wear resistant at the points where they need it, while being able to be softer and able to be pressed and spun mechanically to heat treat them further once they are installed on assembly equipment further down the line.
 
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BreeStephany

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Chuckster in NJ said:
Only one ground electrode?……. Nothing going to building steel?
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The ground rod is to help dissipate excess RF that is collected on the enclosure of the machine and the brass mesh cage surrounding the coil to remove 'ambuent' RF noise so that it does not bleed back on the equipment grounding conductor and effect equipment elsewhere. Each machine has 3x separate PLC controllers and a VFD + shaft encoder or DC servo drive within 2' ~ 4' of the induction coil, so reducing RF noise past the coil is very important for machine reliability.

Its also important for operator safety. There is a reason we have big signs surrounding this particular portion of the plant that state that no one with a "pacemaker device" is permitted to enter.
 
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sparky 1971

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It's all above and beyond me. I'll stick with the simple service calls and minor new construction/remodels I've been doing for a long time.

As far as the suit; there have been several times where I should have worn one, but only one time where it was required. The foreman showed up with the suit, took the jacket out of the bag and held it up to me. All I heard was "you're one of those big boy heavyweights, get your fat *** out of here". I wasn't even fat then, I was still in strongman and weighed in at a solid 260. I did require a 3XL shirt though.
 
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BreeStephany

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cvairwerks said:
It's a big microwave transmitter..
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Kind of... its kind of the same principle... but microwaves transmit in the GHz radio frequency range, whereas our machines transmit in the Mhz radio frequency range... but they are running at between 7~10kW, whereas most residential and commercial cooking microwaves run between 600 ~ 1500W.
 
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mike93lx

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BreeStephany said:
Kind of... its kind of the same principle... but microwaves transmit in the GHz radio frequency range, whereas our machines transmit in the Mhz radio frequency range... but they are running at between 7~10kW, whereas most residential and commercial cooking microwaves run between 600 ~ 1500W.
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So how long does a burrito take if you get it in just the right spot?
 
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BreeStephany

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sparky 1971 said:
As far as the suit; there have been several times where I should have worn one, but only one time where it was required. The foreman showed up with the suit, took the jacket out of the bag and held it up to me. All I heard was "you're one of those big boy heavyweights, get your fat *** out of here". I wasn't even fat then, I was still in strongman and weighed in at a solid 260. I did require a 3XL shirt though.
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Every time I have to put mine on, its a reminder that I need to really eat healthier and loose some damn weight... 🤣
 
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