What Causes Electrical Arcing?

Most everyone in the world has seen an electrical arc. Lightning, certain short circuits, and other times when there is literally electricity moving through the air are all Arc Flashes. We’re going to look into the fundamental causes of electrical arcing.   Moving Power Electricity is essentially a charge being conducted through a wire. All electrical charges want to disperse as quickly as possible. They’re like water behind a dam: it always wants to get out. In the case of electricity, the charge wants to disperse, positive to negative. It always wants to get to ground. The problem with this is that we want to actually use the electrical charge, so it can’t go straight to ground. We use insulators to keep the electricity essentially safely inside the wire. Without the insulator, the charge would get out and work it’s way to ground like water out of a burst pipe following gravity. Insulators can be a wide range of things. The rubber casing around wire is it’s insulator. The gigantic, ceramic cones on utility poles are insulators that prevent the charge from trying to discharge into the wooden pole. The air itself is also an insulator. Electricity generally does not want to move through the air. This is why we can have electrical sockets exposed to the open air, but not to water. The air won’t easily conduct an electrical charge but the water will. Water isn’t a great conductor, […]

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The AC/DC Motor

AC and DC Power are different beasts. This has been covered here before and it’s covered to death in training courses for contractors. They seem like oil and water. If you put AC power into a DC application, it’ll end in tears. If you put DC power into an AC application, it’ll end equally in tears. Somewhere along the line, there may even be a ball of fire, some sparks, and an explosion if you mix AC and DC. That begs the question: HOW can one motor work happily with both AC and DC power? It seems a little counter intuitive.   The Expected Problem In a motor using direct current, we expect the power to always move in the same direction. We use commutators to manipulate where that power flows so we can change the magnetic fields, cause changing attractions, and force a rotor to spin. What if we used AC? The field would be reversing rapidly, changing sixty times a second or more. One instance it’s forward, the next it’s backwards. Intuitively, you’d think this sort of power would create vibration. The rotor should lurch right and left a few degrees violently rattling about until something finally breaks. This isn’t the case, so long as some accommodations are made for the different type of power. Like all things, we need to be clever about where we put our wires.   Accommodating AC Power in a DC Motor For […]

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Why Do Transformers Hum?

We recently talked about transformers. Not the robots, but the electrical ones. In a follow up to that, we’re going to look at why transformers are noisy. We’re pretty sure everyone has experienced this noise at some point or other. You’ll find yourself next to an electrical room and hear a loud humming or whining sound. It’s not like the sound of a motor exactly. It’s just this constant, low sound. For those unfamiliar, we found a good recording on Soundcloud below:   What Am I Hearing? Let’s establish what actually makes the sound. Electricity itself doesn’t exactly make noise afterall, it’s just the conduction of energy through metal. Sure, lightning makes a good boom, but that’s totally different. When we talked about transformers, we mentioned that they’re pretty much solid parts, nothing inside moves. There’s no axles, hinges, shafts, or anything noisy. What part of that transformer are you hearing? It turns out, the coils move. In most cases, the coils are too small to make a notable sound or the current going through them isn’t enough to make a loud noise. The transformers powering your HVAC equipment or converting high voltage AC current to your building’s 110 VAC however, are more than sufficient to make lots of sounds. It comes down to just how much material there is and how much energy is making it move. As an aside.. If you put enough power into a transformer, it […]

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