GDT for 230VAC Mains Primary Surge Protection

Question

Problem: GDT for 230VAC Mains Primary Surge Protection. Solve this hands-on electronics task on EWskills.

Accepted Answer

1. Component Purpose

In a multi-stage surge protection device (SPD), the GDT serves as the first stage — it handles the bulk of the lightning surge energy. A downstream MOV (second stage) then clamps the residual transient to a safe level.

The 230VAC mains has a peak voltage of ~325V. With +10% grid tolerance, worst-case peaks reach ~360V. The GDT’s 470V spark-over is above this worst-case peak, so it will never fire during normal mains operation — only on actual lightning surges.

As first-stage protection, the GDT must handle ≥10kA because it absorbs the majority of the surge energy before any reaches the MOV.

Required: 470V Spark-Over · ≥10kA (8/20µs) · 2-Pole · Through Hole · Littelfuse · RoHS

2. How to Find It on DigiKey

Go to DigiKey.com → Circuit Protection → Gas Discharge Tube Arresters (GDT)

Apply these filters:

Voltage - DC Spark Over (Nom) → 470V
Impulse Discharge Current (8/20µs) → 10kA or higher
Number of Poles → 2
Mounting Type → Through Hole
Manufacturer → Littelfuse Inc.
Part Status → Active

Important: After a GDT fires and the surge passes, the mains AC voltage can sustain an arc through the ionized gas (called "follow-on current"). The circuit must include a current-limiting element (series impedance or coordinating device) to ensure the GDT can extinguish this arc.

3. Key Specifications & What They Mean

Specification	Required	Why
Spark-Over Voltage	470V	Above 230VAC worst-case peak (~360V).
Surge Current	≥10kA (8/20µs)	First stage absorbs bulk of lightning energy.
Number of Poles	2	Protects Line-Neutral in one package.
Mounting	Through Hole	Power-stage mounting; robust connections.
Manufacturer	Littelfuse	Company AVL requirement.
RoHS	Yes	Compliance required.

4. Selecting a Safe, Production-Ready Part

The filtered list will show matching parts. Before you pick one, check: Is it Active? Is stock available? Is the manufacturer reputable? Is a datasheet available?

Full checklist: How to Select a Safe, Production-Ready Component — EWskills Guide

5. Filtered DigiKey Link

➡ View Matching Parts — Littelfuse, GDT, 470V, ≥10kA, 2-Pole, Through Hole

46. GDT for 230VAC Mains Primary Surge Protection