TDF – Transient Discriminating Filter


TDF - Transient Discriminating Filter

The Transient Discriminating Filter (TDF) series has been specifically designed for process control applications to help protect the switched mode power supply units on devices such as PLC controllers, SCADA systems and motor controllers. Units are UL® Recognized and available for 3A, 10A and 20A loads and suitable for 110-120V ac/dc and 220-240Vac circuits.

The TDF is a series connected, single phase surge filter providing an aggregate surge capacity of 50kA (8/20µs) across L-N, L-PE, and N-PE. The low pass filter provides up to 65dB of attenuation to voltage transients. Not only does this reduce the residual let-through voltage, but it also helps further reduce the steep voltage rate-of-rise providing superior protection for sensitive electronic equipment.


  • Transient Discriminating (TD) Technology provides increased service life
  • In-line series protection
  • High efficiency low pass sine wave filtering – ideal for the protection of switched mode power supplies
  • Three modes of protection: L-N, L-PE & N-PE
  • 35 mm DIN rail mount – simple installation
  • LED status indication and opto-isolated output – for remote status monitoring
  • ERICO Surge Products are covered by an extended warranty; see the attached document for more information
  • CE, UL® 1449 Ed. 3 Listed
  • USA Approval
  • Canadian Approval


  • Power surge and transient protection for sensitive electrical and electronic loads
    • PLCs
    • SCADA
    • Motor Controllers
    • RTUs
  • Protection of subcircuits or specific equipment which may be remote from point-of-entry protection
  • Protection for rail and transit signal and communication systems

More Information

Part No. Part No.
for Europe
TDF3A120V 700001 120V 1 phase 2W+G, 50kA 8/20µs, 3A series protector
TDF3A240V 700002 240V 1 phase 2W+G, 50kA 8/20µs, 3A series protector
TDF10A120V 700003 120V 1 phase 2W+G, 50kA 8/20µs, 10A series protector
TDF10A240V 700004 240V 1 phase 2W+G, 50kA 8/20µs, 10A series protector
TDF20A120V 700005 120V 1 phase 2W+G, 50kA 8/20µs, 20A series protector
TDF20A240V 700006 240V 1 phase 2W+G, 50kA 8/20µs, 20A series protector

CE (NOM 3A, 120V)
CSA 22.2
UL® 1283
UL® 1449 Ed 3 Recognized Component Type 2

Surge Rated to Meet:
ANSI®/IEEE® C62.41.2 Cat A, Cat B, Cat C

ANSI is a registered trademark of the American National Standards Institute. cULus is a registered certification mark of UL LLC. IEEE is a registered trademark of the Institute of Electrical and Electronics Engineers, Incorporated. UL is a registered trademark of UL LLC.


TDF & DSF data sheet

TDF Series Installation Instructions

Technical Note TN CR 005, The Benefits of TD Technology

Technical Note TN CR 006, SPDs and the Benefits of Filtering