50 Watt Ceramic Power Resistor Case Study

Manufacturers, in an increasingly competitive environment require long term reliability of componentry which can be customised to their application and designed for ease  of assembly and electrical performance. A recent enquiry was from an Australian manufacturer of industrial heating equipment. Their products use high wattage heating elements and large, high air flow fans which circulate heated air. The client had a requirement for a new circuit design that would allow for different fan speeds in the application. A high power resistor with suitable tapping was deemed to be the best solution.

The resistances required were 300 ohms and 470 ohms with a minimum wattage rating of 40 watts.

Custom Solution

We manufactured samples, for evaluation by the customer, of our PW50 flameproof power resistor with a resistance of 470 ohms with a tapping point at 300 ohms, allowing the client to switch between the different resistances to achieve the desired fan speeds. Tappings on a resistor result in a small reduction in the rated wattage, however the clients required 40 watt rating were well within the PW50 resistors specifications. The client tested the samples in their circuitry and confirmed that the resistor met their electrical specifications. However, the client had a limited area to mount the finished resistor assembly and needed the resistor mounted in a vertical axis. We were able to offer the PW50V (vertical mounting option) which has a zinc coated bracket attached to the body of the resistor as shown in the diagram below. This allowed for easy mounting of the resistor, whilst using the least amount of space within the finished assembly.

50 Watt Ceramic Resistor – Vertical Mounting Option

Conclusion

The clients needs for a reliable, customised power resistor were met in a cost effective manner. Cost of the product is one issue. The other less tangible cost savings for the client were in the ease of assembly of the finished product.