SUBSTATION

DESIGN

ENGINEERING

At Varistor Engineering, we are specialized in AIS/GIS substation engineering for 33kV to 400kV grid-connected renewable projects.

Our Substation Design Engineering services cover the complete development of AIS/GIS substations for grid-connected solar projects. We design robust, complianceready substation systems that ensure smooth power evacuation and long-term operational stability. From primary equipment layout to protection, control, and SCADA integration, our engineering approach ensures safety, reliability, and full alignment with utility and regulatory guidelines.

Substation Concept & Philosophy Design

Activities Include:

  • Busbar configuration selection

  • Substation capacity planning

  • Feeder & transformer configuration

  • Redundancy philosophy

  • Switching arrangement study

  • HV/MV/LV segregation philosophy

  • GIS vs AIS technical evaluation

  • Fault-level & equipment rating estimation

Primary System Design (Equipment Layout & Ratings)

Primary Design Includes:

  • Switchyard layout

  • Busbar system design

  • Earth switches & isolators selection

  • Lightning arrester placement

  • CT/PT placement & accuracy class selection

  • Circuit breaker interrupting rating calculation

  • Wave trap & PLCC design

  • Main power transformer & auxiliary transformer sizing

  • Cable trench & duct design inside substation

  • Fire wall requirements around transformers

  • Insulation coordination & surge withstand levels

Auxiliary Systems for Substation

Scope Includes:

  • AC/DC Auxiliary Main Board

  • Battery & charger sizing

  • Emergency DG set & ATS system

  • Fire detection & alarm system

  • Transformer oil containment pit design

  • Control room HVAC system

  • CCTV & security system integration

Secondary System Design (Control, Protection & Automation)

Protection Panel Engineering:

  • Design of C&R panels

  • IED selection (Siemens/ABB/GE/Schneider)

  • Relay configuration

  • Protection logic & grading

  • GIS/AIS bay-specific wiring diagrams

SCADA System

  • SCADA architecture design

  • RTU/PLC configuration

  • Signal mapping through I/O list

  • Remote & local control logic

  • IEC 61850 based system integration

  • Cybersecurity considerations for SCADA

Metering System

  • ABT compliant metering

  • Energy accounting scheme

  • Grid settlement metering philosophy

Substation Earthing & Lightning Scheme

Earthing Grid Design Includes:

  • Step & touch potential check

  • Mesh design & conductor sizing

  • Transformer neutral Earthing arrangement

  • Lightning protection with shielding angle and rolling sphere method

Documentation Provided:

  • Earthing layout drawing

  • Calculation reports

  • Material BOQ

Deliverables (Correct for high-end EPC companies)

Drawings

  • Master SLD (33/66/110/132/220/400kV)

  • Equipment layout

  • Sectional & elevation drawings

  • Cable termination diagrams

  • Interlocking diagrams

  • SCADA & communication architecture

  • Cable trench layout

  • Earthing layout

  • Lightning protection layout

  • Panel GA drawings

  • Wiring diagrams

Plant Auxiliary Electrical Systems

Scope Includes:

  • AC auxiliary distribution board

  • DC distribution system

  • Battery capacity & discharge time calculation

  • DG-set backup system design

  • UPS system for critical loads

  • Lighting system (indoor/outdoor, lux calculations)

  • Emergency lighting & safety signage

  • Earthing pits & ring main design

Reports

  • Design Basis Report

  • Load Flow & Short Circuit Study

  • Protection Philosophy

  • Substation Civil Interface Report

  • Testing & Commissioning Procedures

Engineering Support During Execution

Support Includes:

  • Vendor drawing review

  • Site engineering support

  • QA/QC of electrical installation

  • FAT & SAT support

  • As-built drawings

  • Grid synchronization assistance

  • Testing & commissioning documentation