Pressure Relief & Control

Advanced Overpressure Protection for Critical Transformer Assets

Qualitrol’s Pressure Relief Devices (PRDs) are specifically designed to provide rapid mechanical pressure relief for oil‑filled transformers, load tap changers and other fluid‑filled equipment. When sudden internal pressure spikes occur, these devices open instantly to safely vent hot oil and gas, protect the tank, safeguard personnel, and minimise environmental impact. Once pressure normalises, the devices automatically reseal to maintain system integrity and reduce downtime.

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Application Overview

Qualitrol PRDs are used across the full spectrum of transformer installations—from network transformers (500 kVA and above), large distribution and medium power units, through to large power transformers and load tap changers. They offer precise, reliable pressure relief for equipment operating in utility, heavy‑industry, mobile, and railway environments. Their directed‑flow designs and optional piping systems help ensure hot oil is safely redirected away from personnel and critical components.

What We Solve For

Utilities and heavy‑industry operators face operational, environmental and safety risks due to sudden internal transformer faults that cause pressure spikes. Qualitrol’s PRDs solve these challenges by offering:

Improved personnel safety through controlled directional discharge
Reduced environmental impact by enabling discharge to containment
Reduced downtime thanks to reliable automatic resealing
Extended asset protection via fast‑acting mechanical design

These solutions address safety compliance, environmental obligations and asset‑life optimisation.

TECHNICAL

Features & Functionality

Functionality & Options

Patented gasket and valve designs ensure quick actuation and consistent resealing after pressure subsides, maintaining internal fluid containment.
Both LPRD and XPRD models can be paired with aluminum or PVC piping, protective screens, large‑radius elbows, or compression couplings for safer and cleaner discharge control.
Optional semaphores, indicator pins and alarm switches provide clear notification of pressure‑relief events—locally or through SCADA/monitoring systems.
SPDT and DPDT configurations, high‑DC switches, low‑current gold‑contact types and multiple connector styles support any alarm scheme.
Devices can be top‑mounted horizontally (recommended) or side‑mounted vertically; shields rotate 360° for alignment with containment piping.
Gas bleed systems ensure trapped gases can be safely purged when PRDs are used below the oil level.

Key Technical Specifications

Flow Rate: Up to 12,600 SCFM at 15 PSI (XPRD)
Operating Temperatures:

Ambient: –40°C to +80°COil

Temperature (LPRD): –20°C to +100°C

Materials: Stainless steel valves & hardware; cast or die‑cast aluminum flanges and rings; nitrile, Viton or silicone gaskets; zinc‑plated or stainless‑steel springs
Environmental Testing:

XPRD: 1000 hours salt‑spray exposure

LPRD: 200–1000 hours salt‑spray testing with no structural degradation
Electrical Connections: Multiple circular connectors, flying leads or terminal boxes; dielectric strength 2000–2500 VAC
Recommended Tank Opening (XPRD): 171.5 mm

EXPERIENCE

Our Projects featuring Insulect Disconectors

Explore our project highlights to see where Insulect Disconnectors are making an impact.
For tailored advice on whether this solution suits your network, please connect with our team here.

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Wunghnu Solar Farm

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Fortescue Aldoga, New 275kV Substation Switchgear

ADVANTAGES

Why Choose Our Pressure Relief & Control Devices

Our pressure relief & control devices are designed to keep transformers safe by releasing pressure quickly and preventing damage during unexpected events. They help protect equipment, reduce safety risks and support smooth, reliable operation.

Industry‑Leading Experience &
Proven Performance

With over 50 years of field experience and more than 400,000 units installed globally, Qualitrol PRDs are the most widely specified devices in the industry. Their performance is independently verified and exceeds international standards, ensuring unparalleled confidence in critical protection.

Unmatched Safety &
Environmental Protection

From 12 kV to 145 kV, Insulect offers manual or motorised units, with options for earthing switches, auxiliary switches, and interlocks. Custom footprints and mounting options ensure a perfect fit for greenfield and brownfield installations alike.

Customisable, Durable &
Built for the Long Term

IMPLEMENTATION

Services & Support

Insulect offers comprehensive services and support for the products we manufacture and specialise in, enhancing value for local utilities, major energy users, equipment manufacturers, and service operators.

LOCAL TECHNICAL TEAM

Our local technical team provides exceptional support and expertise, ensuring quick response times and personalised service to tackle any challenges that may arise during project execution.

ENGINEERING DESIGN

Our team utilises advanced technology and industry knowledge to develop innovative and efficient high-voltage switchgear solutions, customised to fit the unique requirements of each project.

PROCUREMENT & LOGISTICS

We facilitate smooth procurement and logistics processes by sourcing from trusted, proven partners and coordinating timely deliveries, ensuring projects remain on schedule and within budget.

TESTING & COMMISSIONING

Professional testing and commissioning support ensure that every high-voltage switchgear system functions safely and reliably, adhering to all regulatory standards and client expectations.

TURNKEY PROJECT DELIVERY

We are able to oversee every phase from concept to completion, providing comprehensive solutions that simplify complex projects and ensure successful outcomes.

FACTORY VISITS

We facilitate client visits to our local manufacturing sites here in Australia, as well as overseas, for initial inspection as well as factory acceptance testing.