Project Overview
Project Type: Existing Substation Equipment Upgrade and Compatibility Retrofit
Commissioning Date: Q1 2026 (Planned)
Location: Port Louis Substation, Mauritius
Client: Central Electricity Board (CEB)
Core Requirement: Replace an aging power transformer within constrained space. The new equipment must be fully compatible with the physical interfaces of the existing 66 kV busbars and 11 kV cables to enable a "plug-and-play" replacement, minimizing outage duration.
Technical Solution
TSTYNICE provides a customized 66/11 kV two-winding power transformer. Its bushing layout and dimensions are meticulously engineered to match the exact positions of CEB's existing busbar and cable terminations, ensuring direct replacement of the decommissioned unit without modifying primary connections.
Core Equipment Specifications
Model: SFSZ11-20000/66
Rated Capacity: 20 MVA
Voltage Ratio: 66 ± 8×1.25% / 11 kV
Frequency: 50 Hz
Cooling: ONAN/ONAF
Insulating Medium: Environmentally friendly synthetic ester oil (optional)
Vector Group: YNyn0+d
Critical Compatibility Design
Precise Bushing Interface Matching:
66 kV Side: Two oil-paper condenser bushings. Their horizontal center distance, height above ground, and mounting flange dimensions perfectly match the existing 66 kV tubular busbar connectors.
11 kV Side: Three silicone rubber composite bushings. Their horizontal spacing, height, and cable termination interfaces (e.g., Type E or F flanges per IEC 60859) are fully compatible with the existing 11 kV XLPE cable terminations.
Spatial and Mechanical Constraints Met:
The transformer's overall length, width, height, and shipping dimensions are within the limits of the original equipment foundation and the substation building entrance.
The positions of all tank-mounted accessories (radiators, conservator, pressure relief device) avoid conflicts with existing platform supports, fire protection piping, and inspection walkways.
Seamless Electrical Parameter Integration:
The short-circuit impedance (Uk%) matches the original equipment, ensuring no impact on system protection settings or short-circuit current levels post-replacement.
The on-load tap changer range and steps meet CEB's voltage control requirements for this node.
Project Execution Strategy
"Minimized Outage" Implementation Plan
Prefabrication and Pre-assembly:
Full-scale model verification at the factory using 3D scan data provided by the client to confirm all interface dimensions.
All accessories (bushings, coolers, control cabinet) are installed and wired prior to shipment for unitized delivery.
On-site Rapid Replacement:
Phase 1 (Preparation, before outage): Position the new transformer on a bypass foundation and pre-set all external connections.
Phase 2 (Switch-over, planned 8-hour outage): Isolate and remove the old transformer; roll the new transformer into position; reconnect the original 66 kV busbars and 11 kV cables; perform core electrical tests.
Phase 3 (Re-energization and Monitoring): After energization, conduct continuous online monitoring including dissolved gas analysis (DGA) and partial discharge (PD).
Testing and Verification
Factory Tests: In addition to routine tests, an "Interface Compatibility Verification Test" is performed using simulated fixtures to confirm the mechanical and electrical contact performance of all bushing connectors.
Site Verification: Provide infrared thermography services to ensure no hotspots develop at any new-old interfaces under load.
