Electronic – Using a TVS diode instead of, or in addition to a MOV for AC line protection

movtvs

For 220 V AC mains voltage, is it good practice to replace a 300 V MOV with a 300 V bidirectional TVS diode (like in here http://www.littelfuse.com/products/tvs-diodes.aspx), or connect both in parallel? Are there any points that need to be considered?

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Best Answer

It comes downto what are you trying to protect against

There are four main types of transient suppression devices

Gas Tube

  • Protection time: > 1us
  • Protection Voltage: 60 - 100V
  • PowerDissipation: Nil
  • Reliable Performance: No
  • Expected Life: Limited
  • Other: Only 50-2500 surges, can short powerlines

MOV

  • Protection time: 10 - 20ns
  • Protection Voltage: > 300V
  • PowerDissipation: Nil
  • Reliable Performance: No
  • Expected Life: Degrades
  • Other: Fusing required. Degrades

Avalanche TVS

  • Protection time: 50ps
  • Protection Voltage: 3-400V
  • PowerDissipation: low
  • Reliable Performance: yes
  • Expected Life: long
  • Other: Low power dissipation. Bidirectional requires dual

Thyristor TVS

  • Protection time: <3ns
  • Protection Voltage: 30-400V
  • PowerDissipation: Nil
  • Reliable Performance: yes
  • Expected Life: long
  • Other: High Capacitance

http://www.onsemi.com/pub_link/Collateral/HBD854-D.PDF

( http://web.archive.org/web/20051001082352/http://www.onsemi.com/pub/Collateral/HBD854-D.PDF )

http://www.vishay.com/docs/88440/failurem.pdf