Why Do We Use Belts?

It’s getting hot out, you turn on your AC, and everything works great for about an hour or two. Outside, your condenser reaches saturation, it’s cooling fan doesn’t budge, and soon the house is back to the sweltering mess it had been before. It’s unbearable, but there you are. Welcome to Summer, right? The Belt Drive There are a ton of applications where we need something to spin, whether it’s a fan, blower, or even the drum in a washing machine. We often use a belt to connect the blower and anything else back to a single motor. Eventually that belt gives out and needs to be replaced. This could be from simple wear and tear, rot, or even accidental damage, like running over a rope with a tractor, jamming up the mower deck blades, and then burning up the belt with friction. Belts offer a number of advantages though. They’re cheap to manufacturer, flexible, and can reduce the total number of parts a given machine needs. A belt can power multiple output devices, synchronize those output devices, and it frees up the designers to create different designs with fewer parts or more compact layouts than could otherwise be achieved. But WHY?! You could put the blower right on the motor! Belts also serve two other majorly attractive purposes in cutting down costs. A belt allows us to do gear reduction and it allows us to use some cheaper (but […]

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Engine Driven Air Conditioners

The world of HVAC is a very strange place to live some days. We commonly think of air conditioners as being electrical devices. Perhaps the only real exception to that is the air conditioner in your car, which is essentially powered by your car’s engine. In the early days of air conditioning and refrigeration however, the opposite was true: cooling systems were mainly mechanically powered.   The World Before Electricity It’s the early 1900s. The telephone is still considered cutting-edge technology and you can go down to the local train station to send a telegram anywhere in the country. Electricity however, was not quite so common. In 1900, 3% of US homes had electricity. It wasn’t entirely feasible to just throw an air conditioner in your back room. Even businesses wouldn’t have had the easy option of just plugging in an air conditioning system, even if it occupied half their building. At this point, most working-power was mechanical. Factories would have massive boilers, which produced steam, that turned enormous turbines or ran crank systems, that ultimately ran everything in the facility. In order for any particular innovation to take off, it almost had to be mechanically driven. If you couldn’t throw some coal and water in a machine to power it, you probably couldn’t have it.   Steam Powered AC How exactly do we run an air conditioner on steam alone? Every motor in an air conditioner is doing just […]

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Why is my 2 Stage Furnace Always Running?

After our talk on short cycling, we came across people with the opposite complaint: their furnaces were running constantly. As opposed to constant short cycling, these people were experiencing some form of long cycle. Their furnace would fire up, warm the office, and then keep running. There would be constant, mechanical sound from the machine. This is exactly what it’s supposed to do.   Wasted Heat In a single stage furnace, the thermostat calls for heat, the furnace runs, and once the target temperature is reached, it all shuts down. This is horrendously wasteful. Your furnace has just  burned fuel or used electricity to get a heat exchanger red hot. When the furnace shuts down, that heat exchanger is still roasting, glowing red, but its not using that heat. The heat exchanger will just sit there, cool down, and an extra ten, twenty, or even thirty minutes of warmth has just been completely wasted. The excess heat in the exchanger will go into the ambient air in the furnace. It might heat some of the basement or perhaps the furnace will have a tiny bit less work to do next time. In any event, it’s resources spent that aren’t making you more comfortable. This situation is analogous to approaching a red light, flooring the car, and then slamming on your brakes. All that gas to speed up is probably being burned for nothing.   Using Idle Heat There’s not really much […]

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Why Use an Electric Actuator?

In many ways, electric actuators are the holy grail. They are precise, efficient, fast to respond, have low support requirements, can be bought cheaply, can be easily retrofitted into existing environments, and in principal can be configured for absurd output torque. There aren’t a lot of downsides here. We’ve harnessed hydraulic and pneumatic power to move things, but that was always a multi-step procedure. With electronics? Nearly everything is built right into the actuator.   Minimal Install Requirements Facilities using hydraulics and pneumatics need to provide hoses, valves, pumps, compressors, reservoirs, and more. It’s a lot of hardware just to make something move. That’s a lot of money, maintenance time, and space just to have your fully automated, multi-zone heating system. It’s a lot even if you’re automating a brewery or bakery, where the equipment will ultimately save time and money. Facilities using electrical actuators however, need only provide power and control signals. In some cases, multi-phase power is required, but that mostly boils down to some extra electrical panels and service wires. Each actuator is pretty much independent and will operate regardless of what the rest of the facility is doing. That’s less hardware to keep track of, fewer failure points, and overall easier maintenance. In terms of a retrofit in existing facilities, that pretty much means you remove the old actuator, install the new one, and plug it in. In principal, it’ll just plugin and work. It’s hard […]

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Why Use a Hydraulic Actuator?

There are 3 principal ways to power an actuator. There’s electrical, pneumatic, and hydraulic actuators. Generally speaking, the most expensive set up is going to be a hydraulic system. A single hydraulic actuator can cost ten times what a pneumatic or electrical one would. This begs the question, why would you buy something with such a premium?   Basics of Hydraulics This all starts with the simple fact that fluids don’t compress. You can put water in a sealed piston and push down on it, but all it will do is distribute that force to the walls of the piston. Maybe it’ll squeeze in by 1/1,000,000,000th of its volume, but in large part, one liter of fluid is going to always take up that volume. This is amazingly useful. It means we can use fluids as an almost universal connection. Think about it, to connect a powerful motor to anything, you need linkages, gears, chains, and bulky hardware. It’s noisy and takes up a ton of space. If you want to connect multiple devices to that motor, they all need to either run at the same time and speed or require complex gearboxes to connect or disconnect them. This would take up a ton of space and make our modern lives suck in innumerable ways. With a hydraulic system however, we can get around all this bulk. There can be one or two large motors, powered by anything that fits […]

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Motor Vs. Actuator

For a lot of people, motors and actuators may seem like the same thing. Movement is involved, they may well sound the same, there’s some kind of energy source going in, and there’s no way your facility will function without both of them. In principal, they both use the same technologies, they can even look the same, but they’re different beasts.   The Easy Difference The easiest way to tell a motor and actuator apart is by how they’re being used. A motor is designed to spin at a relatively high RPM for significant spans of time. Think of the motor in your AC Compressor, a fuel pump, the mixer or coffee grinder sitting on your kitchen counter. If you turned it on and left it to function forever, there would be no consequences except for the motor failing. By contrast, an actuator has a linear output, instead of a continuous output. It moves a damper, valve, elevator, or some other device that has a limited range. Think about your car door, it can be all the way open, half open, closed, or anywhere in between. If you wanted to mechanically open it, that’d be an ideal job for an actuator. If you used a simple motor, you’d run the risk of going over 100% open or over 100% closed, and damage/destroy the door. If you used a device that isn’t intended to stop at an exact position, you’d break […]

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How Does a Solenoid Work?

At it’s heart, an electric motor is converting a pushing and pulling motion into a rotational motion. The coils on the rotor all pull in opposite directions from opposing sides, which makes things spin. What if we didn’t have opposing sides and we weren’t trying to spin? We’d make the ‘rotor’ pop up and down instead, wouldn’t we? Applications This […]

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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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How does a VFD work?

We’ve explained Electric Motors in principal, but we all know it’s not that simple. In large part, the guts are pretty similar in most electric motors. It’s windings and magnets, which can be arranged in difference sizes and positions, to get a specifically desired performance. In the examples we gave, it was assumed that the electrical power going in was constant. What if it wasn’t?   Less Than 100% On-Time What if we didn’t keep dumping power into the motor? Think of it like a manual transmission. We know we need power to push ourselves up a hill, but we can push in the clutch (put it in neutral) and coast down the other side without using engine power. We can do this with an electrical motor, gaining a massive amount of control and performance out of it. If we attach some sensors and measure the RPM, we can determine when it needs power and when it doesn’t to maintain a given speed or torque output. This difference in driving the motor means we may power the motor for only 1/10th of a second, every other 1/10th of a second. Thus, we end up with something that might look like: -_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_-_ Power on, power off… Power on… Power off. The motor only does a tiny bit of work when it needs to. This cuts down on waste heat and allows us to cheaply regulate the power going into the motor. […]

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How Does an Electric Motor Work?

Some time ago, we talked about transformers and transformers that hum. That was a pretty interesting concept. Electricity can make things move thanks to electromagnetism. When you put energy into something in just the right way, it produces a magnetic field. We can probably all remember messing with magnets in our youth, watching how no matter what, we couldn’t make […]

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