For applications that require high surge capability and must operate in harsh environmental conditions, TT electronics IRC Wirewound and Film Technologies Division provides the W20 Series of vitreous enameled wirewound resistors. Their lead-free, vitreous-enamel coating allows the resistors to withstand the harsh environments and high temperatures found in industrial applications, such as chemical processing machinery, welding equipment, industrial motor controls and power-generation systems. The resistors are suitable for current inrush and surge protection circuits for power supplies, motor controllers and circuit protectors.
According to Keith Chipman, product manager for IRC’s Wirewound and Film Technologies Division, “The W20 series resistors’ vitreous enameled coating essentially seals the wirewound resistor element in a glasslike material that makes the device impervious to even the harshest environments,” he explained. “The protective coating and markings are resistant to all normal industrial cleaning solvents used for printed circuits.”
The W20 Series resistors are rated for 3 W, 5 W, 7 W, 10 W and 14 W with limiting element voltages between 100 V and 750V.
Resistance ranges are 0.1 Ω to 100 kΩ with standard tolerances down to ±1%. Typical TCRs are between +75ppm/°C and +200ppm/°C, with an operating temperature range from -55°C to +200°C. The W20 Series resistor pricing begins at $0.29 each in quantities of 1000.