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Our Silicon carbide varistors are made from about 90% silicon carbide of different grain sizes and 10% ceramic binder and additives. The raw material is formed into various varistors geometric dimensions and then sintered under specific atmospheric and ambient conditions at a high temperature.
A layer of brass is then flame sprayed on as an electrical contact. Other standard metallized contacts include Aluminum, Copper, Nickel and Silver. In the case of disks, an electrical connection is created by clamping a metal plate to each side of the disk using tie rod. Large assemblies in the case of disks are fashioned using metal plates with tab connections on each side of these disks to create series and parallel stacks of disks to provide appropriate overvoltage protection for high power. Smaller disks simply have tinned copper wires soldered to the brass layer and can be further processed to include a dielectric coating.
Geometries are manufactured to suite the electric values required by varying the OD, ID, thickness and length. Our manufacturing process yields good voltage dependences and high energy absorption.
Key features of Silicon Carbide Varistors
- Self-Healing.
- Used in Air/ Oil/ SF6 Environments.
- Configurable into Single or Modular Assemblies.
- Extremely High Ampacity.
- High Surge Energy Rating.
- 100% Active Material.
- Repeatable Non-Linear Characteristic.
- High Voltage Withstand.
- Essentially Non-Inductive.
Below is a list of our standard diameter disks 37, 45, 60, 80, 95, and 150mm: Energy absorption per disk ranges up to 122,290J allowing disk assemblies with extremely high energy absorption ratings in the tens of Mega-Joules.
Mechanical Parameters
Description |
Abbreviation |
Range |
Outside Diameter |
Do |
37 to 150 mm |
Inside Diameter |
Di |
10 to 30 mm |
Length |
L |
2 to 25 mm |
Standard Disk Specifications
Electrical Parameters
| Item |
Range |
| Operating Temperature Range |
-40 to 150°C |
| TCV (Typical Temperature Coefficient of Voltage) |
-0.12 to 0.18 %/°C |
| TCI (Typical Temperature Coefficient Current) |
0.5 to 0.8 %/°C |
| Specific Heat Capacity Approximately |
2 J/cm³/°C |
| Thermal Conductivity |
0.07 W/cm² . °C/cm |
| Inductance |
nH’s (non-inductive) |
SiC Disk Applications
- Mains overvoltage from lightning, inductive or capacitive coupling.
- Switch contacts with inductive load.
- High switch-off voltages in transformers, motor and generator windings and magnet coils.
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