Power resistors, able to withstand and dissipate large amounts of power, have a wide range of applications within the marine sector. Choosing the correct components  when building or refurbishing a ship is essential to ensure productivity and efficiency remain elevated. Resistors are required for many purposes including dynamic braking, ship stabilization and improving power quality using harmonic filters to protect delicate machinery on board. With so many applications for resistors, there are some important considerations to bear in mind when choosing which resistor is suitable for the job at hand.
 
As power resistors dissipate energy as heat, marine requirements such as ingress protection (IP) ratings for enclosures can reduce airflow, modulating the resistors’ ability to work effectively. However, water and oil cooling systems are already present on the majority of large ships. Some resistors on the market are able to use these cooling systems, but careful planning is required prior to installation.
 
Each application that requires a power resistor will have unique requirements, including electrical resistance and power rating.
The resistance, measured in ohms (Ω), determines how effectively the resistor transforms the electricity into heat energy, whereas the power rating, measured in watts (W), is the amount of power that can safely pass through the resistor without risking damage. As the power rating is measured and defined at standard conditions and is extremely dependent upon the final operating conditions, changes should be expected when used in the marine sector. Therefore, it may be wise to install a resistor with a power rating in excess of what is expected.
   
Resistors with an insufficient power rating may become overloaded, carrying a risk of fire, which is extremely dangerous on ships. In addition to damaging the ship structure, the confined space makes it immediately dangerous for workers and equipment on board the vessel. On the flip side, resistors with higher power ratings are typically made of more expensive materials, meaning the cost of the resistor is higher.
 
Microhm has the expertise to produce bespoke resistors, specifically designed to meet electrical needs while fitting into tight areas. Space is often particularly restricted in ship  machine and engine rooms, where resistors are usually installed, so small off-the-shelf resistor solutions are often installed.