Vitreous Enamelled Wirewound Resistors WZO Series – TT Electronics Datasheet

Category: Electronics, Resistors, TT Electronics PLC

Overview of TT Electronics’ WZO Series Wirewound Resistors

TT Electronics presents their WZO Series of Vitreous Enamelled Wirewound Resistors, showcasing a range of high-quality resistors designed for enduring harsh environments and ensuring high stability and reliability. This datasheet delivers comprehensive details about the resistors’ specifications, construction, performance data, and applicable standards.

Electrical and Physical Specifications

The WZO Series includes models like W21, W215, W22, W23, and W24. These resistors exhibit power ratings that span from 3.0 watts to 14.0 watts at 25°C. The resistance range spans from 0.1Ω to 100KΩ, available in tolerances of ±1%, ±2%, and ±5%. The temperature coefficient of resistance (TCR) for these models typically remains below ±15 ppm/°C but can reach a maximum of ±200 ppm/°C. The resistors surpass or meet the rigorous BS CECC 40-201-002 requirements.

Construction and Resistance to Environmental Influences

The series is engineered with a high purity ceramic substrate and interference-fit end caps with welded termination wires. A resistive element wound on the substrate is coated with a vitreous enamel that not only provides protection but also contributes to the resistor’s strength, thermal impedance, and flammability resistance. These resistors remain impervious to all standard industrial cleaning solvents suitable for printed circuits and are inherently non-burning due to the use of inorganic materials in their construction.

Performance and Reliability

Under the commercial power ratings, the WZO series demonstrates excellent performance over 1000 hours at 25°C, with a change in resistance value (∆R%) maintained well within acceptable limits, showing high stability over time. They are rated for a climatic category of 55/200/56 and showcase robustness and a strong resistance to solder heat, damp heat, temperature changes, vibration, and bump tests.

Marking, Packaging, and Application Notes

Each resistor in the series is clearly marked with the type reference, resistance value, and tolerance, following IEC 62 standards. The resistors come in various packaging options tailored to their models—for instance, W21 and W215 are provided in Ammo Packs, while W23 and W24 are available loose-packed.

Application notes caution users against bending the termination closer than 6mm to the body of the resistor and recommend taking care in placements to prevent overheating during high-temperature operation. The solderability of terminations and the minimum lead lengths reflect TT Electronics’ commitment to ease of use and compatibility with standard soldering processes.

Regulatory Compliance and Global Standards

The resistors come with CECC approval, ensuring compliance with established global standards, and all Pb-free parts adhere to the latest RoHS3 requirements. TT Electronics guarantees the series’ performance in line with their stringent product specifications and quality control measures.

All information is considered accurate at the time of publication, but TT Electronics reserves the right to amend specifications without prior notice.