Six SEL 700G- New Install

A San Diego data center expanded its on-site generation capacity by installing a new cogeneration plant consisting of six MAN engines paired with Marathon generator packages. Because the facility supports critical infrastructure, ownership required a protection system capable of providing comprehensive fault detection, coordination, and long-term reliability.

To meet these requirements, six SEL-700G units were installed to protect each generator. The SEL-700G was selected for its depth of protection, measurement accuracy, and advanced diagnostic capability.

Unlike basic protection devices, the 700G provides full generator protection including phase and ground overcurrent, reverse power, negative sequence, loss-of-excitation, over/under voltage, over/under frequency, and breaker failure protection. It also offers high-resolution event recording and oscillography, allowing operators to review and analyze system disturbances in detail.

San Diego Power engineered and programmed the protection schemes for all six units. This included reviewing CT and PT configurations, developing coordinated trip logic, and establishing breaker control sequences aligned with the plant’s operating strategy. Each relay was configured to ensure selective fault clearing and proper coordination with downstream distribution equipment.

Following installation, comprehensive functional testing was performed to verify alarm logic, trip outputs, metering accuracy, and overall system performance under both normal and simulated fault conditions.

The relays were fully integrated into the plant’s monitoring systems, providing real-time visibility into generator status and electrical parameters.

The completed project delivered a coordinated and modern protection platform for the new cogeneration system

Controls and Emissions System Upgrades

SDP recently completed a project where we upgraded the control systems on seven Waukesha 7044 Engines. The existing controls at that site were outdated, unsupported, and increasingly unreliable. We replaced the legacy Encorp and 2301A systems with the same suite of modern Woodward and WAGO equipment.. This included Easygen 3500XT-P2 controllers, ProAct Gen 3 all-electric actuators, 2301E digital speed controls, AFR-PD-R-64R air/fuel ratio controllers, and WAGO remote I/O systems with Axiomatic thermocouple scanners.

SEL 700G Retrofit

SDP was contracted to replace an aging GE Multilin 489 relay that had reached end-of-life. The existing relay was obsolete, parts were no longer available, and manufacturer support had been discontinued. To maintain reliability and streamline future maintenance, we recommended upgrading to a SEL-700G protection relay.

Our team started by removing the existing GE unit and preparing the cabinet for retrofit. The new relay required modifications to the cabinet door and mounting layout, which were completed on-site to ensure a clean, secure fit.

With no existing configuration or wiring documentation available, every input and output had to be identified and verified manually. Our technicians carefully traced each circuit, documented connections, and programmed the new relay to match the original system logic while utilizing the expanded I/O capabilities of the SEL-700G.

After installation and programming were complete, we performed a full functional and system test to confirm all alarms, trip circuits, and status indicators operated correctly. The relay passed all checks, and the system was placed back in service.

The upgrade to the SEL-700G provided several key benefits, including improved reliability, expanded programmable I/O capacity, and enhanced visibility into system performance. The new relay also offers ongoing manufacturer support, modern firmware updates, and long-term serviceability. These advantages are not available on their current Multilin and Otay Water has already expressed interest in upgrading several additional systems with the same relay platform.

Full Engine Overhaul

During a scheduled service on a Waukesha 7044, oil samples were taken as part of routine maintenance. The analysis showed elevated metal content, and further inspection confirmed metal shavings in the oil system caused by a failed bearing. Because bearing material had circulated through the engine, a full overhaul was required to prevent further damage and restore reliability.

SDP removed the engine from service and completed a full teardown. The rotating assembly was inspected, damaged bearings were replaced, and the lubrication system was thoroughly cleaned to eliminate contamination. The crankshaft and related components were measured and verified to manufacturer tolerances. All cylinder heads were replaced as part of the overhaul.

New bearings, gaskets, seals, and required wear components were installed during reassembly. Once rebuilt, the engine was refilled with new oil and coolant, pre-lubed, and started under controlled conditions. The unit was brought up to temperature and monitored to confirm proper oil pressure, temperature stability, and overall performance.

The overhaul restored the engine to reliable operating condition and addressed the internal bearing failure before it resulted in catastrophic damage.