Isolator Testing & Commissioning

Spectrum Isolator Testing & Commissioning

Isolator Testing & Commissioning
Critical Safety for Maintenance Operations

An isolator—also known as a disconnect switch—is a critical safety device in substations and switchyards. It provides visible, physical separation of electrical circuits, ensuring safe maintenance and preventing accidental energization.

Key Function: While isolators don't break load current like circuit breakers, their mechanical integrity and alignment must be tested thoroughly before commissioning.
Our Testing Process Get Quote

Types of Isolators We Test & Commission

Comprehensive testing for all isolator types from 11 kV to 400 kV in AIS and GIS substations

Single Break Isolators

Simple design, used for low to medium voltage levels

  • Cost-effective solution for distribution systems
  • Reliable mechanical operation
  • Easy maintenance and operation

Double Break Isolators

Enhanced isolation for higher voltage applications

  • Superior isolation characteristics
  • Used in high voltage substations
  • Better voltage distribution across breaks

Pantograph Isolators

Space-efficient design for congested switchyards

  • Vertical movement saves horizontal space
  • Ideal for busbar congestion areas
  • Commonly used in AIS substations

Centre Break & Double Side Break

Widely used in 66 kV to 220 kV yards

  • Easy operation and maintenance
  • Reliable for medium to high voltage
  • Standard design for transmission substations

Earthing Switch-Integrated Isolators

Combine isolation with grounding function for enhanced maintenance safety

  • Provides visible earth connection
  • Ensures equipment is safely grounded during maintenance
  • Mechanical interlocks prevent unsafe operation
  • Compact design saves space
  • Enhanced safety for personnel
  • Compliance with safety standards

Why Isolator Testing is Critical Before Commissioning

Operator Safety

Prevents accidental energization during maintenance operations

System Reliability

Ensures correct mechanical operation and alignment

Compliance

Meets IS/IEC/CEA safety and operational requirements

Prevents Flashover

Verifies insulation strength under high voltage stress

Smooth Operation

Reduces wear and tear on mechanical linkages

Visible Isolation

Confirms clear isolation gap for safe maintenance

Our Isolator Testing & Commissioning Process

Following IS 9921, IEC 62271, and CEA safety guidelines

1. Pre-Installation Checks

Visual Inspection:

Identify transport damage, corrosion, or loose fittings

Foundation Verification:

Ensure base frame is level and properly anchored

Nameplate Verification:

Confirm ratings, type, and model match design requirements

2. Mechanical Testing

Alignment Check
All moving arms and blades correctly aligned with fixed contacts
Operating Mechanism Test
Smooth manual or motorized operation without excessive force
Interlock Testing
Electrical/mechanical interlocks with circuit breakers
Operating Time Measurement
Opening and closing time for motorized isolators

3. Electrical Testing

  • Insulation Resistance (IR): Between phases and phase-to-earth
  • Contact Resistance (CRM): Low resistance across closed contacts
  • High Voltage Withstand: Dielectric strength verification
  • Motor Control Circuit: Limit switches and auxiliary contacts

4. Functional Checks & Commissioning

  • Visible Isolation Gap: Verify adequate gap after opening
  • Earthing Switch Operation: If integrated with isolator
  • Sequence Interlocks: Prevent load switching with breakers
  • Final Energization: Verify isolation gap under voltage stress

Real-World Example

220 kV Pantograph Isolator Commissioning in Haryana

Pantograph Isolators

220 kV AIS Substation, Haryana - 2023

Project Highlights

Challenge: Limited space between existing busbars in operational substation

Solution: Custom mechanical alignment and phased installation to avoid shutdown of other bays

100%

Pass rate for contact resistance and alignment tests

2 Days Early

Project completed ahead of deadline

Safety & Compliance Standards We Follow

  • IS Standards: IS 9921 for high-voltage switches and isolators
  • International Standards: IEC 62271 for high-voltage switchgear
  • Safety Practices: Lockout/tagout, PPE compliance, hazard marking