Halogen Free Busbar Insulation for a Metro Depot Substation

Client Background

A metro operator was refurbishing the switchgear in a depot substation. The project specification required halogen free materials throughout because the substation sits below a station concourse.

Project Challenge

Insulate the 33 kV busbar system including 64 bolted lap joints that maintenance has to open for torque checks and thermographic survey, using halogen free materials only.

Customer Pain Points

• Halogen free specification ruled out most busbar insulation products on the market
• 64 bolted lap joints that a tube cannot conform to
• Maintenance requirement for the joints to remain inspectable
• An assembly programme with no time for the workshop to measure and cut tube

Our Solution

S1(n)-35 halogen free tube on the straight bar runs supplied cut to length and labelled per position. S1-B molded lap joint covers tooled to the joint geometry with a buckle closure so maintenance can open and refit them without damage.

Manufacturing Process

Tube extruded and radiation cross linked in Dalian in a halogen free RoHS compliant formulation. Covers molded in tooling made to the customer's joint drawing with a first article supplied for fit approval.

Supply Chain Coordination

First article covers shipped and fit checked on the actual bar before production tooling was committed. Production delivered in one shipment timed to the assembly programme.

Quality Control

Dielectric strength volume resistivity heat aging and low temperature flexibility tested per lot. Every production cover checked against the approved first article.

Final Result

The workshop fitted tube straight from the labelled bags with no measuring or cutting. The 64 covers fitted first time. Thermographic survey at commissioning was carried out with the covers opened and refitted in under an hour.

Customer Benefit

A halogen free busbar system that meets the depot specification and still allows the maintenance regime the operator's asset policy requires.