Why Can a GDT Keep Conducting After a Surge?
A gas discharge tube (GDT) can finish diverting the specified surge and still remain conductive. Once the tube has fired...
Protection Circuits
How Should the Third Lead of a Thermally Protected MOV Be Wired?
The third lead on a thermally protected metal oxide varistor (MOV) often invites the wrong first question. Designers ask whether...
Why Do MOV Leads and PCB Traces Increase Residual Voltage?
Why can the voltage at a protected circuit exceed the metal oxide varistor (MOV) clamping voltage in the datasheet? The...
Can a Fuse Replace an MOV Thermal Disconnect?
If an AC input already has a fuse, does the MOV still need a thermal disconnect? The fuse does not...
MOV Placement: Line-to-Line vs Line-to-Ground Protection
An MOV placed across line and neutral does not solve the same problem as an MOV placed from line to...
MOV Failure Modes and Thermal Protection
A metal-oxide varistor (MOV) protects a circuit by conducting transient current when voltage rises into its nonlinear region. That useful...
MOV Protection Circuit Basics: Placement, Fusing and Layout
Learn where an MOV sits in a protection circuit, what a fuse can and cannot do, why thermal disconnection matters,...
