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Varistor - Slide6

One of the most significant changes from 2nd to 3rd edition was the change in type designations. The 2nd edition classified SPDs as Permanently Connected, Direct Plug-In or Cord Connected. The 3rd edition bases the type designations on the location of the SPD within the electrical system and added type designations for components and component assemblies. Type 1 is for location between the service entrance and the line transformer. Type 2 is for location on the load side of the service disconnect panel. Type 3 is called “Point of Use”. This location must be a minimum of 10 meters from the service panel. Type 4 is for component assemblies such as an integrated MOV and thermal protection device. The Littelfuse TMOV series would be an example of a Type 4 category device. Type 5 is for individual components such as the Littelfuse MOV line of products.

PTM Published on: 2012-08-31