Electronic – Parts identification: Y-cap, MOV or NTC


I am having problems identifying whether a component is an Y-capacitor or a MOV.
They are from my parts bin so I do not know beforehand what they are.

Is there a simple way to know the difference without searching for the part number or measuring them? If measurement is required, what is the capacitance usually for a "standard" MOV?

Two examples of the components I'm talking about.
First example
Resistance: inf

Second example
Resistance: inf

Some more…things that are probably different things but it a similar package:
several oddballs
Resistance from top left:
inf, inf , 11 Ohm, 5 Ohm, 55 Ohm

I think the middle one is a transient-voltage-supression-something but i don't know about the others.

Best Answer

Capacitors often have a safety rating of an X or Y class, also some logos of safety agencies. If you find X1, X2, Y1 or Y2 in the marking: EMI capacitor, intended for use at the input filter of a device. The other markings often state the capacitance (222 means 22*102 pF = 2.2 nF), the tolerance (e.g. J = ± 5%; K = ± 10%; M = ± 20%) and the rated voltage.

MOVs often have some logos of safety agencies. Their number is composed of the disk size (7 mm, 10 mm, 14 mm, ...) and the breakdown voltage.

Inrush current limiting NTCs often have a number composed of the disk size and the resistance at room temperature. Also, NTCs become very hot when "on". Their surface is not glossy (plastic/resin), but often rough (ceramic-like), because the epoxy dip used for caps and MOVs would burn at the temperatures the NTCs have when in use.

Especially for MOVs and NTCs, there are very many small and cheap manufacturers, so there is really no standard for the marking.

Related: Practical lesson in capacitor types, what is the value of these capacitors?, Identifying Capacitors