TT Electronics presents the WZO Series of Vitreous Enamelled Wirewound Resistors, designed to meet strenuous demands in a variety of applications. Suitable for harsh environments, these resistors feature a lead-free vitreous enamel coating that enhances their durability and performance. They are ideal for use in protection circuits thanks to their excellent overload characteristics, and they promise high stability and reliability. The series fulfills the requirements of the EU Directive 2011/65/EU and its amendment (EU) 2015/863 (RoHS3), ensuring compliance with environmental standards.
Electrical Data
The WZO Series offers resistors with commercial power ratings ranging from 3.0W to 14.0W at 25°C and from 2.5W to 7.20W at 70°C. The resistors come in resistance ranges from 1Ω to 100KΩ with tolerances of ±1%, ±2%, and ±5%. The temperature coefficient of resistance (TCR) is typically below ±15 ppm/°C, with a maximum of ±200 ppm/°C, ensuring reliable performance across a wide temperature span (-55°C to 200°C).
The BS CECC 40-201-002 requirements outline the style and electrical specifications, such as power rating and resistance range, for the resistors. These requirements are either met or exceeded by the WZO Series products, allowing them to cater to both commercial and approved applications.
Physical and Constructional Features
The construction employs a high-purity ceramic substrate with end caps and termination wires welded for a robust assembly. With a protective vitreous enamel coating, these resistors boast excellent resistance to industrial solvents and are inherently non-flammable, making them highly suited for printed circuit board applications. The termination material is a copper-clad steel wire, nickel-plated and solder-coated, meeting IEC solderability and strength requirements. Additionally, resistors are clearly marked with the type reference, resistance value, and tolerance, following the IEC 62 standard.
Performance and Reliability
The WZO Series resistors demonstrate commendable performance over extended periods, with negligible changes in resistance after thousands of hours of operation across various environmental tests such as dry heat and damp heat exposure. Their physical properties remain intact even in the face of temperature fluctuations, vibration, and short-term overloads. Furthermore, they exhibit excellent pulse handling and insulation resistance, providing reliable and predictable performance in diverse usage scenarios.
Application Notes
Proper handling and packaging methods are recommended, with specific guidelines provided for bending terminations and determining clearance distances to prevent overheating. Packaging options vary by resistor type, including Ammo Packs and tape and reel, ensuring flexibility and convenience for users. It is also noted that vitreous enamel’s insulation resistance decreases with temperature, requiring consideration in high-temperature applications.
TT Electronics delivers this information in the datasheet and reserves the right to amend specifications without notice. The current documentation reflects accurate specifications at the time of publication, underscoring the company’s commitment to providing timely and reliable data for its products.
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