Wastewater treatment plant SCADA and motor control
Upgraded motor controls and instrumentation power for a 25 MGD treatment plant, with soft starters on large pumps and a hardened controls power system tied to standby generation.
What we were engaged to build.
Actual ratings, devices and standards.
The service voltages, equipment ratings, protective functions and codes this project was built and tested against.
The specific electrical solutions we used.
How each design decision solved a real constraint on this project — from redundancy and coordination to protection and commissioning.
Solid-state soft starters on large pumps
Ramping the 150 HP pumps over 15 seconds cut inrush from 600% to 350%, protecting the generator and stopping the voltage sag that used to drop PLCs on every start.
UPS-backed controls power bus
A dedicated 208/120V controls bus on a small UPS keeps PLCs, instruments and SCADA alive through a generator transfer, so the plant never loses visibility during an outage.
NEMA 4X stainless for corrosive zones
Enclosures near the aeration basins are 316 stainless NEMA 4X with sealing gaskets and stainless conduit, surviving the H2S and moisture that ate the old painted steel.
4–20 mA + MODBUS RTU to SCADA
Every loop is a 4–20 mA signal with a live-zero fault indication, and the MCCs report breaker status over MODBUS RTU, so a failed instrument reads as a fault instead of a false normal.
From the build.
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