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RPC and LED's?

RonRock

Aluminum
Joined
Mar 18, 2012
Location
Underwood, IA
I built my RPC following direction and very much help from many on the forum. It has been working perfectly for a few years now, love it. In that time I have been able to get a couple other 3 phase machines other than the Bridgeport that I started with. Very nice to be able to use my RPC and run 3 phase.

So the question. One of the machines that I have been running off my RPC is a Doall ML16 bandsaw. One of the best machines in my shop. But it has a couple issues I'd like to resolve. The Doall is 3 phase drive motor, but has a transformer that runs the blade welder, and blade grinder, as well as a light on the welder and light for the saw blade. The lights are 120V incandescent. Will my RPC work for LED's if I was to replace the original fixtures? I'd like to keep original, but the flexible "stalk" on the blade light is "sprung" and it will not hold position. No surprise the lamp assembly is very heavy.

The light for the blade welder is missing completely, so it will have to be replaced with something, not sure how I will do that yet.

Maybe someone has some parts for a Doall ML16 they will sell me? I also need the Circular wheel cast backing. My wheel is good, but the cast part is bad.

Anyway, the reason for my question is that I don't recall that my RPC supplies a neutral. So not sure if an LED will work.

Long winded, sorry.
 

sfriedberg

Diamond
Joined
Oct 14, 2010
Location
Oregon, USA
If you buy 120V fixtures to replace your existing 120V fixture, it will not matter what the bulb technology is. The existing fixture obviously has a complete supply&return path, and so will the replacement fixture. On delta 3-phase (no neutral) equipment, it is not unusual to power 1-phase accessories across two legs of the 3-phase. These two legs serve as the supply&return for the 1-phase accessory.
 

RonRock

Aluminum
Joined
Mar 18, 2012
Location
Underwood, IA
If you buy 120V fixtures to replace your existing 120V fixture, it will not matter what the bulb technology is. The existing fixture obviously has a complete supply&return path, and so will the replacement fixture. On delta 3-phase (no neutral) equipment, it is not unusual to power 1-phase accessories across two legs of the 3-phase. These two legs serve as the supply&return for the 1-phase accessory.

Thank you, that is what I was hoping. I should have mentioned another reason for my concern. My wife bought a car jumper box "Halo" brand. It also serves as a power supply for power outages. It has a 120v receptical that is supposed to capable of powering a 65W draw. Few weeks ago power went out. Oh goody I'll try my Halo she is excited to give it a try. Plugs in an LED lamp and no joy! I don't recall the stated draw but I'm sure that it was less than 65W. Seems like 23W. So I swapped bulbs for an incandescent and it worked. I figure there must be something in the LED bulbs that don't work with the battery. Made me wonder about my lamps.
 
Last edited:

sfriedberg

Diamond
Joined
Oct 14, 2010
Location
Oregon, USA
It also serves as a power supply for power outages. It has a 120v receptical that is supposed to capable of powering a 65W draw.
The problem is mostly with the jumper box, rather than the LED lamps. The jumper box has an invertor in it which converts low-voltage DC to higher voltage AC, and it probably generates a really crappy waveform. LED lamps that plug into 120V AC sockets have driver circuitry in them which convert 120V AC back down to low-voltage DC. And possibly those driver circuits are sort of half-assed, too. The really crappy wavefrom coming from the jumper box is preventing the possibly half-assed driver circuits from working properly.

Relevant note: Some LEDs are dimmable, and others are not. This capability is provided by the driver circuits built into the LED lamps. The dimming works by recognizing and dealing with really crappy waveforms.

If you have real AC power, coming from the utility, even half-assed LED driver circuits will work fine.
 

RonRock

Aluminum
Joined
Mar 18, 2012
Location
Underwood, IA
The problem is mostly with the jumper box, rather than the LED lamps. The jumper box has an invertor in it which converts low-voltage DC to higher voltage AC, and it probably generates a really crappy waveform. LED lamps that plug into 120V AC sockets have driver circuitry in them which convert 120V AC back down to low-voltage DC. And possibly those driver circuits are sort of half-assed, too. The really crappy wavefrom coming from the jumper box is preventing the possibly half-assed driver circuits from working properly.

Relevant note: Some LEDs are dimmable, and others are not. This capability is provided by the driver circuits built into the LED lamps. The dimming works by recognizing and dealing with really crappy waveforms.

If you have real AC power, coming from the utility, even half-assed LED driver circuits will work fine.


Thank you. Good explanation.And gives me another reason to buy an oscilloscope. Don't know how to use one but pretty sure I need one.
 








 
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