FHS-OCT24-PG06+07_Layout 1 21/10/2024 12:00 Page 7
EDITOR’S CHOICE
HEAVY-DUTY WITHOUT HEAVINESS Another common challenge with DBRs is their size and weight. Since DBRs are required to dissipate large amounts of energy, resist chemical and thermal wear, and withstand vibrations and mechanical shock, weight can become an issue if not factored into the component’s design. The cooling method used also impacts the size of the resistor. Natural convection or air cooling, in which warm air naturally rises and cools in a steady air flow, is used for low power drive systems. However, for heavy-duty applications with high heat transfer, a stronger approach is required, such as forced convection cooling. This method of cooling relies on fans, which add to the resistor’s overall bulkiness. Liquid cooling is the more efficient choice for
solids from zero to six, and the second grades the level of protection against liquids from zero to nine. Resistors used for mining benefit from sealing to IP56 level, preventing harmful dirt, dust and pollution from damaging the elements. Across different applications, DBRs are
exposed to variable damage factors. For this reason, it is crucial to consider the primary risks associated with the end use environment when selecting resistor materials.
high power applications with limited space. A water-cooled resistor takes up ten per cent of the size and 15 per cent of the weight of an equivalent air-cooled resistor. Additionally, water has a higher thermal conductivity than air and can transfer heat much quicker, allowing for faster cooling. Liquid cooling is also suited to continuous, high temperature applications as it can sustain stable temperatures for long durations, reducing the risk of overheating. For high power automotive, traction and marine systems, Cressall’s water-cooled EV2 resistor allows for individual units to be combined into a scalable high power solution that can handle up to 1.0MW power. This
modular design means manufacturers can save space by only combining the exact number of units required for the application.
BALANCING SAFETY AND EFFICIENCY In industrial processes, efficient performance yields high productivity, consistent quality and cost reductions. However, by their nature, DBRs waste energy by dissipating it as heat rather than reusing it. For this reason, some manufacturers dismiss dynamic braking in favour of regenerative systems that restore energy generated during braking to be reused. For example, in electric vehicles (EVs), regenerative braking allows for the vehicle battery to be recharged by excess energy. However, DBRs are still needed to make regenerative braking safe and effective. If the battery is already full or there is a failure, the energy cannot be transferred to the battery and needs to be safely dissipated instead. Integrating a DBR into the system of an EV with regenerative braking offers a solution which still optimises energy efficiency but safeguards the braking system. These two technologies can work together to make the most of excess energy generated during braking and safely dissipate that which cannot be used to charge the battery. In addition, some DBRs are able to recycle this
excess energy within the vehicle. For instance, Cressall’s advanced EV resistors convert energy into heat that can be used to pre-heat the battery or warm the cabin of the vehicle. DBRs do not have to be equated with inefficiency, as they perform a crucial role in systems with regenerative braking and can be optimised to reuse kinetic energy where possible. Across different applications, potential DBR challenges will vary. With so many factors to consider, working with a trusted partner can streamline the process of selecting the appropriate DBR. With decades of experience designing and manufacturing resistors for a range of applications and demanding environments, Cressall can provide expert guidance and support, helping manufacturers to achieve the best outcome for their electric drives.
Cressall Resistors
www.cressall.com
FACTORY&HANDLINGSOLUTIONS | OCTOBER 2024 7
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58
