Application Specific Power Resistor
We specialise in application specific power resistor design and manufacture. We deliver thick film power resistor solutions in low to medium volume.
We work with customers to understand the application and all resistor design issues to ensure we design and manufacture a power resistor product that is fit for purpose.
Thick film power resistors have several advantages over wire wound alternatives. These include small size (high resistance density) significantly lower cost, lower inductance (faster frequency response) and improved thermal management (heat sinking). Thick film power resistors are also more resistant to mechanical, thermal and chemical stresses than their wirewound equivalents.
Power resistor applications include protection devices and power dissipation applications. Our products are used in InRush protection applications, High Power / High Voltage Load Banks, grounding resistors, current sensing applications, motors and snubber circuits among others.
To discuss your application specific power resistor requirements contact TSEC today.
Thick Film Power Resistor Design Issues
When choosing a thick film power resistor for any application it is important to consider more than the resistance value, power rating and tolerance. There any many factors that can affect the performance of the resistor. It is important to understand power resistor manufacturing limitations and their impact on the design process.
In most applications, the objective will be to minimise the power resistor dimensions. However, this objective can conflict with thermal management and mechanical issues that could impact on the performance of the resistor in the final application.
It is vital the thick film resistor manufacturing process does not leave the power resistor device more prone to damage by one, or more, external stresses. Minor defects can make the resistor less resistant to mechanical damage. Track abrasion can cause thinning (hot spots) and lead to failure under surge conditions. A poor choice of materials can result in thermal performance issues.
Failure to consider these issues during the power resistor design phase may not only impact on the performance of the resistor it could also dramatically shorten the effective in service life of the device.
There are several power resistor design issues to consider including:
• Thick film power resistors are used in a wide range of applications to prevent damage to sensitive components from start up conditions, switching applications, and electromagnetic interference. Transients and pulses need careful consideration as they can cause an instantaneous temperature rise in the resistor film and damage the resistor.
• The standard operating conditions (particularly peak voltage) and long term loading effects must be evaluated. Failure to select the correct power resistor can result in changes in resistance over time or premature resistor failure.
• Heat management in thick film power resistor devices is critical to reliable long term resistor performance. A heatsink can be used to dissipate heat away from the resistor but it is also important to manage the system environment. Components surrounding the resistor on the circuit board and the effect of temperature rise on their operation should be considered.
• Power resistor design and the choice of appropriate material for both the substrate and the conductor material is important if resistor failure or reduced long term performance is to be avoided.
There is lots to consider. TSEC Engineers are always available to offer advice on thick film power resistor selection for any application.
Required Power Resistor Application Information
To ensure all potential issues are considered we require the following information before starting the power resistor design process.
• Nominal resistance (Ohms).
• Resistor tolerance.
• Operating temperature.
• Peak voltage.
• Any known transient conditions.
• Dimensional constraints.
• Termination type (and length of pins).
• Coating material (if any).
Power resistors are used in a wide range of applications where component failure cannot be tolerated. The resistor design and manufacturing process is the key to success.
TSEC has supplied numerous components for Resistor Load Banks with power ratings as high as 25 KWatts @ 140 KVolts. Other examples include High Power Resistors 100 mm by 50 mm on 1 mm thick Alumina Ceramic that can handle 500 Watts provided the element temperature is kept constant at approximately 60 °C
Please contact TSEC on 01207 230728 to discuss your thick film power resistor manufacture and design issues.