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Dynamic brake resistors are electric elements incorporated into a locomotive or other heavy-electric machine to enable safe braking. As such, it will be crucial for a dealer to know the various types of dynamic brake resistors because they come in different types, according to the industrial braking system into which they will be incorporated.
Therefore, below are the main dynamic brake resistor types and their operational specifics:
Wire wound dynamic brake resistors
Dynamic brake resistors are wire wounds of resistive wire on an insulating core. When customers prefer it, this type will have a high power rating, meaning that it will be appropriate in heavy electric braking. Wire wound dynamic resistors are also known for their durability, and one can easily operate them at higher temperatures. All of these qualities help make this kind of resistor a darling in heavy industries.
Grid-style dynamic brake resistors
Grid-style dynamic brake resistors feature a grid or mesh pattern made of metal. Customers who value compactness above all other things will most likely like this dynamic resistor since it can fit into very limited spaces. Moreover, this type of dynamic resistor also disperses the heat very well, making it very efficient at dissipating the braking energy that is being generated.
Cement-type dynamic braking resistors
These will utilize cement or a ceramic material to support the resistor wires. A notable advantage of these dynamic brake resistors lies in their high temperature tolerance. Hence, even though they are used less frequently than two other types of dynamic brake resistors, their high-temperature tolerance is always appreciated when needed.
Non-wire wound dynamic brake resistors
Unlike wire wound resistors, these are constructed without winding the resistive wire. All of these resistor types have flat, bar, or strip configurations. Customers will sometimes prefer these non-wire wound resistors as they provide a more significant surface area for heat dissipation. This feature also enables these resistors to handle high power levels reliably. Note that non-wire wound dynamic braking resistors also prove themselves in continuous operation. This is particularly advantageous in steady electrical braking systems because it provides constant performance.
Dynamic brake resistors serve to protect electric motor systems by absorbing and then dissipating the excess energy that is generated during the braking process. A good understanding of what these brake resistors are really used for is important for dealers, as this can inform them of the market needs and so stock relevant products.
In electric trains and trams
In electric trains and trams, dynamic braking is one of the most frequently used braking methods, especially when the vehicle is descending an incline or in the process of stop. Here, the electric traction motors will operate as generators under the dynamic braking conditions. The dynamic brake resistors will absorb the generated electrical energy, thus preventing the voltage from rising dangerously high. This keeps the operational safety of the train systems and prevents any damage that over-voltage can cause.
In mining equipment
Large machinery that is used in mining, such as electric shovels and draglines, are frequently brought to a stop using dynamic braking. This is particularly applicable under conditions where mechanical braking may be considered a safety hazard or may be economically unviable. The dynamic brake resistors will absorb the regenerative energy that the motors generate during this braking process. Hence, this is popularly used in mining activities, where large amounts of kinetic energy must be safely absorbed and then dissipated during braking.
In large industrial fans, pumps, and compressors
Many large industrial electric fans, pumps, and compressors are frequently fitted with dynamic braking systems. When the rotating mass in any of these machines is brought to a stop, the motors will generate electrical energy. The dynamic brake resistors act as an energy absorption sink in these machines. They give off this energy as heat, so they protect the motor and electronic control systems from the damaging effects of voltage spikes.
In material handling systems
Automated systems that handle materials within industries provide other applications for dynamic brake resistors. Conveyor belts, hoists, and other motor-driven equipment are normally brought under control using dynamic braking. The dynamic brake resistors in these systems will improve braking efficiency and provide electrical energy. They will help with this by absorbing the energy that the equipment inertia will generate during braking.
Knowing the specifications of dynamic brake resistors ensures two things: the optimal operation of these resistors and that there is no mismatch between these resistors and customers' requirements. Considering these nuances also contributes to a better understanding of the product, thus allowing for informed decision-making when selecting this product.
Power rating
The power rating of dynamic brake resistors can range anywhere between 20 kilowatts and 420 kilowatts. High power ratings, which may be several hundred kilowatts, are provided for large-scale applications like trains and industrial fans.
Resistance value
Resistance values can range from 1 ohm to more than 1000 ohms. This will depend on the specific application and the operating voltage. Larger voltages will require larger resistance values to curb all of the regenerative currents.
Operating temperature range
Dynamic brake resistors will normally be designed with temperature ranges that span 25 degrees to 70 degrees Celsius. However, those dynamic braking resistors that are built for high-end applications can reliably function at temperatures that are higher than this.
Material construction
These brake resistors will usually incorporate either wire wound, grid, or cement, as was explained above. All materials, electric insulators, or ceramics have their unique thermal and electrical performance properties.
Mounting configuration
Dynamic brake resistors will be designed for both forced and natural cooling. Dynamic braking resistors that need cooling are frequently mounted with a fan above them or are in a way that airflow over them will be maximized. Others that don't require cooling can be mounted in such a way that airflow over them will occur naturally.
Braking control system integration
Many dynamic brake resistors will have their operation controlled automatically by an electric braking control system. This system will monitor parameters such as motor speed and generated voltage. The electric braking control system will decide when the dynamic brake resistors are to be engaged to absorb the excess energy.
Dynamic brake resistors have to be well maintained if their lifespan is to be prolonged. Some ways in which this can be cleaned or inspected and how their installation can be affected will help prolong their lifespan.
Install in a cool area
It is equally important to ensure that dynamic braking resistors are installed in environments where they will not be subjected to excessive dust, moisture, or physical impact. Proper ventilation around dynamical brake resistors is as important as space with no obstruction to their associated cooling fans.
Regular cleaning
Dynamic brake resistors are likely to accumulate dust and debris over time. It, therefore, makes it important to clean them frequently since accumulated dust will hamper their cooling ability. One must use a clean dry cloth or soft brush and not harsh chemicals or wet cleaning methods.
Inspect for physical damage
One also has to routinely inspect these dynamic brake resistors for signs of physical damage. Check for cracks or other obvious signs of wear and tear, as this can affect the overall performance of these resistors. The wires or the grid should also be checked for corrosion or signs of breakage.
Monitor operating conditions
One must ensure that these resistors don't operate at excessive temperatures. Use temperature sensors to monitor the resistor surface temperature to avoid this. If at any time the temperature is found to be higher than normal, one has to ensure that cooling system works properly.
Regular electrical checks
One has to measure the resistance values occasionally using the multimeter. This helps to ensure these resistors are functioning as required. Any significant variance will mean that it is time to replace those resistors so that they do not affect system performance.
A1: The brake resistor selection will depend on the voltage and the current generated by the braking action. The voltage will dictate the resistance of the resistor, while the current will give the power rating. For more accurate results, do consult a professional or any relevant online calculator. They are widely available, so finding them shouldn't be much of a problem.
A2: As for the dynamic electro resistors, customers should look out for temperature extremes, physical damage, unusual noise, or even a burning smell. All of these are tell-tale signs that a dynamic braking resistor might not be in good working condition. If they notice any of these signs, it will be best advised for them to seek professional advice.
A3: Yes, dynamic electric vehicle braking resistors that are designed specifically for electric vehicles are aimed at improving energy performance. They absorb all the kinetic energy and later return it to the available electric energy in these vehicles. The good news is there are many such braking resistors on the market. There are also various types of braking systems to help address various electric vehicle problems.
A4: To do this, ensure dynamic braking resistors are regularly serviced and inspected for physical or electrical damage. Ensure they are also placed in cool, dry areas with lots of airflow, as this will reduce their operating temperature. One must measure their resistance values often to avoid overloading. However, using cooling systems such as fans around these resistors is one way to enhance their lifespan and improve their function as protectors of electric systems.
A5: Yes. Dynamic braking resistors might also be used along with capacitors or batteries in energy storage systems. These systems will store the energy that would otherwise be dissipated as heat for later use. This invention has proved very useful, especially in industries that emphasize energy efficiency like renewable power systems.
