Which arrestor type would be used for protecting equipment at higher continuous operating voltages?

When considering the protection of equipment at higher continuous operating voltages, it's important to understand the characteristics of the different types of arrestors mentioned.

An 8.4 kV MOV (metal oxide varistor) arrestor is designed to handle surge protection and is effective for medium voltage applications. However, for continuous operating voltages higher than this level, its effectiveness might be limited depending on the specific system voltage.

A 10 kV MCOV (maximum continuous operating voltage) riser arrestor is specifically designed to protect against over-voltage conditions while allowing for a higher continuous functioning voltage. This makes it suitable for applications where the system operates at or near 10 kV.

The 12 kV gap arrestor provides robust protection in systems operating at voltages around or above this level by utilizing gas discharge to clear faults. It is well-suited for high voltage environments and offers additional surge protection.

Since all three types of arrestors can be effective in protecting electrical equipment at higher continuous operating voltages, they each find their applications depending on the specific needs of the power system. Therefore, using a combination or selection of any of these arrestors would indeed provide a desirable level of protection in scenarios involving higher voltages.