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Normally before VSDs can be shipped, customers need to visit Zest's Brazil factory for a Factory Acceptance Test (FAT). But bans on international travel made physical attendance for the week-long detailed test and equipment requirements impossible. 

Zest's factory technicians were instead able to conduct each element of the FAT remotely for the contractor and end user, both based in Johannesburg, using high-definition cameras and web-based communication software.

"These are extraordinary times, and require extraordinary measures," said David Spohr, business development executive for high-voltage equipment maker. "This has shown that the testing can be done to the same standards, but with significant savings in time and cost."

The order consisted of 7MW 3300V WEG MVW01 VSDs for the ball and SAG mill drive application and two 1.2MW 3300V WEG MVW01 VSDs, Zest said on its website. Adding complexity, the applications required non-standard features, including "frozen charge protection" software on the ball and SAG mill application, which measures torque to avoid system damage.