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EMC Series Film Resistors

TT Electronics/Welwyn EMC series perform three circuit protection functions in a single component

EMC Series TT Electronics/Welwyn EMC series is aimed at line (mains) input inrush limiting in power supply applications where UL approval is necessary. The EMC series has UL recognition, which is a component status indicating that a sample has been tested and verified by Underwriters Laboratories as suitable for use in a safety critical application. The relevant standard is UL1412, which covers fusing resistors designed to prevent fire by safely breaking a circuit under fault conditions. EMC parts perform three circuit protection functions in a single component:
  1. The series provides protection against supply line voltage transients, often in conjunction with a shunt element such as a varistor or transient voltage suppressor (TVS). This enables the designer to achieve the required level of immunity to conducted lightning induced surges.
  2. EMCs restrict the peak inrush current at switch-on to levels suitable for the rectifier bridge and consistent with good EMC design.
  3. EMCs prevent fire by fusing safely under fault conditions such as rectifier or capacitor breakdown.

Digi-Key P/N Manufacturer P/N Description
985-1020-1-ND EMC2-22RKI RES 22 OHM 2W 10% AXIAL High-Capacitance MLCC Datasheet
985-1021-1-ND EMC2-33RKI RES 33 OHM 2W 10% AXIAL
985-1022-1-ND EMC2-47RKI RES 47 OHM 2W 10% AXIAL
985-1023-1-ND EMC2-68RKI RES 68 OHM 2W 10% AXIAL