Southern States

While in school, I worked three semesters in the Power Switching Division at a high-voltage switchgear manufacturer called Southern States in Hampton, GA. They make equipment you see in substations to break high-voltage circuits and temporarily divert current through various auxilliary circuit elements for power-factor correction (like capacitor banks for hospitals w/ MRI machines).

A capacitor bank (left) with the "CapSwitcher" product (right)
A capacitor bank (left) with the “CapSwitcher” product (right) [Image Source]
This was a very interesting field to work in and learn about. Significant technology goes into breaking current at hundreds of kilovolts: special contacts, very fast actuating mechanisms, sulfer hexaflouride (SF6) dielectric gas, and complex internal nozzle shapes to direct the gas and extinguish the lingering arc.

CapSwitcher mechanism
CapSwitcher mechanism [Image Source]
A group of three LLS-II interrupters in the field
A group of three LLS-II interrupters [Image Source]
A spike of voltage post-break called transient recovery voltage (TRV) – analogous to water hammer in pipes – can cause a “restrike” that will re-establish an arc across the contacts, even in cases where an open-air disconnect switch has spread the contacts many feet apart.

Restrike at a substation
Restrike at a substation [Image Source]
Even static geometry in a high-voltage structure has to be carefully evaluated for dielectric strength, and “corona rings” are added to manipulate the local electric field and reduce the chances of a “flashover” – a current discharge that circumvents an insulator with undesirable results.

Corona rings on a disconnect switch
Corona rings on a disconnect switch [Image Source]
The insulator has special geometry to prevent flashovers by eliminating paths water could use to connect two contacts and also increasing the cumulative surface distance an arc would have to skip across to bridge the gap. Mineral deposits on the surface decrease dielectric strength over time, so the industry has standards for how much linear surface is required on the insulator stack based on the voltage difference. Each product is high-pot tested with a giant million-volt (capacity) tesla coil on-site to ensure proper dielectric performance. These tests were awesome to witness. The air crackles as the AC voltage locally breaks down its bonds back and forth.

Tesla coil used for hi-pot testing
Tesla coil used for hi-pot testing [Image Source]
While at Southern States, I designed and tested various new products and components. I ran and documented mechanical and environmental durability tests on new applications of existing products and on current products with new parts. Part of this was physically assembling switchgear on the engineering pad with a boom lift. I made daily notes and fixed equipment issues as needed.

Boom lift on the engineering pad
Boom lift on the pad

I also designed (and built some) custom fixtures and actuators to aid in manufacturing and assembly. For one of these fixtures, I wrote a MATLAB program to work out the leverage and angle needed for a small-framed operator to actuate a partially-assembled interrupter without exceeding the shaft’s side-load allowance.

I also wrote a MATLAB program to characterize the operating-arm load profile of an interrupter switch as it is actuated. This allowed us to properly size the components involved to avoid future field failures.

During my work there, some of the heat-treated parts in our CSH product had an issue with hydrogen embrittlement, so I researched the potential causes and developed a quality-inspection process to prevent the future issues.

A group of three CSHs at the Hoover Dam
A group of three CSHs at the Hoover Dam [Image Source]
I also investigated numerous manufacturing and assembly problems and then implemented improvements to save time, money, and warranty claims.