As part of a long-term modernization project at the Baltimore Washington International (BWI) Airport, Helios Electric was retained to perform design-assist, system integration, and on-site field engineering services.
The project involved replacing an existing 7.5/10.5 MVA outdoor substation transformer and performing retrofit services at the corresponding medium-voltage switchgear lineups. The project also included enhancements to the electrical system protection since power reliability was deemed vital for airport operations.
SEL-787 transformer protection relay
A new SEL-787 transformer protection relay was installed to perform advanced transformer monitoring, controls, and system protection. New pilot control devices were installed on the corresponding switchgear lineups to indicate transformer faults, alarms, and mechanical conditions.
Vacuum circuit breakers at the existing switchgear lineups were retained and modified to establish connectivity with the new substation transformer and the new transformer protection relay.
transformer protection functions
This installation approach yielded improved protection for the new transformer while limiting the scope, budget, duration, and power outages required to accomplish the necessary tasks.
The improved transformer protection functions included the following:
- ANSI-87 – Current Differential Protection
- ANSI-87G – Restricted Earth Fault Protection
- ANSI-50/51 – Phase Overcurrent Protection (Backup)
- ANSI-50/51G – Ground Overcurrent Protection (Backup)
- ANSI-63 – Transformer Sudden Pressure
- ANSI-71 – Transformer Low Oil Level
- ANSI-49 – Transformer High Winding Temperature
- ANSI-26 – Transformer High Oil Temperature
AC/DC control modifications
To fulfill the customer’s desired requirements, the Helios Electric team investigated the internal circuitry of the switchgear lineups and ascertained the specific AC/DC control modifications required at the existing.
Work performed under this project included the following:
- Examining and analyzing the components and sub-components of the existing switchgear lineups.
- Tracing the existing 35kV-class and 15kV-class vacuum circuit breakers to determine the existing field configuration.
- Developing modified equipment shop drawings for approval, construction, and as-built conditions.
- Programming and configuration of SEL-787 Transformer Protection Relay to establish system protection, controls, and integration with the facility’s Supervisory Control and Data Acquisition (SCADA) System.
- Installing and modifying existing 35kV-class and 15kV-class vacuum circuit breaker controls to accommodate the new substation transformer and transformer protection relay.
- Developing Operation & Maintenance (O&M) manuals for modified electrical equipment lineups.
- On-site electrical equipment training for airport maintenance personnel.
