ZOTUP IN PILLS | SPD TRIGGER, LIMITATION, AND COMBINED: HOW AND WHEN TO INSTALL THEM?

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Whether it's a TT or TN system, protection against indirect contacts (i.e., hazards resulting from contact with conductive elements that may become energized in the event of main insulation failure) is achieved in various ways, including adequate grounding of masses and the installation of residual-current devices that detect current leakage to the ground. However, the choice of surge protective device (SPD) is influenced by several parameters, including the possibility of positioning it upstream or downstream of the residual-current device. In this episode, we compare the wide range of ZOTUPLIMITERS (limitation SPDs) with ZOTUPGAPS (trigger SPDs) and ZOTUPCOMBS (combined SPDs).

ZOTUPLIMITERS: Limitation SPDs

ZOTUPLIMITERS, also known as limitation SPDs, are surge limiters that offer an extremely effective protection level (Up) with very fast response times (≤ 25 nanoseconds), thanks to the presence of the varistor, and are characterized by the NFC No Follow Current® function. They can be installed where protection against indirect contacts is not required (TN systems) or where protection is guaranteed (e.g., downstream of a residual-current device in a TT system).

ZOTUPGAPS: Trigger SPDs

On the other hand, ZOTUPGAPS, also known as trigger surge protectors, offer less effective Up protection levels compared to the limitation counterpart (usually around 1.5 kV minimum) and slower protection times (≤ 100 nanoseconds). They also have a follow-on current from the grid and are typically chosen in installations where protection against indirect contacts is required (i.e., TT systems upstream of residual-current devices) as they provide galvanic separation internally.

... and ZOTUPCOMBS?

Enter the category of combined SPDs that incorporate both trigger and limitation components with a varistor. Typically installed in TT systems upstream of the residual-current device, they are particularly suitable for residential environments (condominiums). They offer galvanic separation to the ground with a good level of protection and short response times (≤ 25 seconds between L-N) while maintaining the characteristics of ZOTUPGAPS between N-PE.

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