Resistor Definitions
'A', 'B', 'C', 'D/E', 'F-L', 'M', 'N', 'O', 'P', 'R', 'S', 'T', 'V-Z'

Varistor Description.

Varistor: A resistor that changes value with applied voltage. A varistor may also be called a VDR [Voltage Dependent Resistor], or MOV [Metal Oxide Varistor]. Varistors or MOV devices are used in parallel with the load or component being protected.
Graphic drawing of a Varistor Symbol
Varistor Symbol

Varistors will have a negative voltage coefficient. Reference How to Derate a Varistor, also Companies Manufacturing Varistors.

Varistor Sizes.

Varistor size shown per Commercial Item Description [CID], A-A-55564/3 with a voltage rating of 14v rms to 115 volts rms, with a peak current of 3000 amps.
However as with any component, varistors come in a number of styles in addition to leaded; base mount for high energy and SMD chip styles for space savings applications [0402, 0603, 0805, 1206, 1210 sizes].
Picture of a physical Varistor
Varistor
Physical Dimensions of a Varistor
Varistor Shape and Dimensions

Varistor Characteristics.

Voltage - Current Varistor Characteristics Graphic
Varistor Characteristics Curve




Military Specifications.

MIL-PRF-83530; General Specification for Voltage Sensitive Resistors [Metal-Oxide Varistor]

Commercial Item Description.

A-A-55562 Resistor, Voltage Sensitive (Varistor, Metal Oxide), Chip
A-A-55562/1 Resistor, Voltage Sensitive (Varistor, Metal Oxide), Chip, Style 0603
A-A-55562/2 Resistor, Voltage Sensitive (Varistor, Metal Oxide), Chip, Style 0805
A-A-55562/3 Resistor, Voltage Sensitive (Varistor, Metal Oxide), Chip, Style 1206
A-A-55562/4 Resistor, Voltage Sensitive (Varistor, Metal Oxide), Chip, Style 1210
A-A-55562/5 Resistor, Voltage Sensitive (Varistor, Metal Oxide), Chip, Style 0402
A-A-55564 Resistor, Voltage Sensitive (Varistor), General Specification
A-A-55564/1 Resistor, Voltage Sensitive (Varistor), Base Mount
A-A-55564/2 Resistor, Voltage Sensitive (Varistor), Metal Oxide, High Energy
A-A-55564/3 Resistor, Voltage Sensitive (Varistor), Metal Oxide, Radial Lead

There are two or three different symbols used to indicate a varistor. Ultimately it comes down to what software an engineer uses and how that software represents the part on a schematic.

 
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