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Your Guide To Dynamic Resistors

Trains and the locomotives pulling them can weigh anywhere from 40 tons to 500 tons depending on the number of axles. And, as you can imagine, the heavier the train, the harder it is to slow it down.

It takes massive amounts of energy to slow down a heavy mechanical system.

Before dynamic braking systems, we used to apply mechanical force manually. Someone would run down to the end of each car and turn a wheel applying the brakes. This often didn’t work fast enough, and trains crashed.

Primarily since the advent of the diesel engine, we use more reliable systems to slow down mechanical systems.

Trains might be the most common example, but you’ll find dynamic braking systems in elevators and cranes too.

To help these systems to operate quickly, smoothly, and efficiently, engineers created dynamic resistors. Without resistors, these systems would be clunky and possibly dangerous.

Here are the various features and specifications of this all-important braking component.

1. What Does a Dynamic Resistor Do?  

There are two kinds of dynamic resistors. One is rheostatic or dissipating, and the other is regenerative.

Dissipating braking resistors essentially recycle kinetic energy and turn it into electrical energy. The energy in the case of trains comes in the form of heat.

This energy returns to the supply line where it overloads the circuit and slows down the mechanical system. This is a lot like using your manual transmission to help slow your car down a steep grade.

If the resistor is rheostatic, its main function is to cool the braking system. But even these resistors can become overheated forcing operators to revert to mechanical systems.

Often dynamic braking systems use both kinds of resistors.

Unfortunately, dynamic braking isn’t sufficient on its own to slow down a massive train. Most systems combine dynamic brakes with air brakes.

2. What Are the Advantages of Dynamic Braking?

Friction braking systems do work. On their own, they can stop a train. But on a steep grade, they’re less reliable.

The other problem with friction systems: they wear down faster.

Just like car brakes, mechanical brakes on a train eventually wear down. When adding the extra force from dynamic motors, you extend the life of the friction braking system.

Speed. That’s the most significant advantage of adding electrical braking to your system.

You slow down faster. But this also means you can push your train to go faster.

The second most significant advantage is cost. Not only will you use less energy to slow down the train, but you also won’t have to replace components like brake shoes.

Lastly, because you’re converting heat energy into electrical energy or dissipating heat through resistors, there is less chance of fire or failure. Mechanical brake systems cause too much heat when not assisted. This means your brakes are more likely to fail.

Dynamic Resistors Are Important

Dynamic resistors are incredibly crucial in train operation. You won’t likely find a contemporary locomotive without this kind of braking system installed.

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