In oil and gas, petrochemical, refining and fuel storage facilities, cathodic protection power supplies often need to be installed in classified hazardous zones. The default approach in many plants is to place transformer rectifiers in a safe area and run long DC cables to the protected asset. While this avoids the cost of certified equipment, it creates a set of inefficiencies that compound over the life of the system: significant voltage drops, higher transformer voltage rating requirements, increased installed cable costs, slower commissioning and ongoing power waste.
Hockway™ Transformer Rectifiers, manufactured by Corrpro Europe at our UK facility, offers an alternative. Our ATEX , IECEx and UKEx certified transformer rectifier range is designed and built specifically for installation in Zone 1 and Zone 2 hazardous areas, placing the cathodic protection power supply where it is needed and removing the cable run challenge entirely.
What are ATEX and IECEx Certified Transformer Rectifiers?
ATEX is the European framework for equipment intended for use in explosive atmospheres, defined by EU Directive 2014/34/EU. Any electrical equipment installed in a classified hazardous zone within the EU and UK must comply with the directive and carry CE and UKCA marking accompanied by an ATEX certificate from a notified body.
IECEx is the equivalent international scheme administered by the International Electrotechnical Commission. IECEx certification is widely accepted in markets outside the EU, including the Middle East, Asia and parts of Africa.
For cathodic protection power supplies, the relevant hazardous area classifications are:
Zone 1: An area in which an explosive gas atmosphere is likely to occur in normal operation
Zone 2: An area in which an explosive gas atmosphere is not likely to occur in normal operation, and if it does occur, will persist for a short period only
Equipment is also classified by gas group (IIA, IIB, IIC) and temperature class (T1 to T6). Hockway™’s hazardous area transformer rectifier range covers Zone 1 and Zone 2 applications across the most common gas groups encountered in oil and gas operations.
Why Install Transformer Rectifiers Directly in the Hazardous Zone?
When a plant has a large concrete surface and the protected asset (a pipeline, tank farm or process structure) sits within a hazardous area, the standard approach of using a safe area transformer rectifier with long DC cable runs introduces measurable problems. Specifying a hazardous area certified Hockway™ unit and installing it close to the asset addresses each of them.
1. Long cable runs are eliminated
The most visible benefit is the removal of hundreds, or sometimes thousands, of metres of armoured DC cable from the project scope. In a typical tank farm or refinery, routing cathodic protection cables across concrete surfaces requires cable trays, ducting, support structures and significant civil work. Eliminating that scope removes both capital cost and project programme risk.
2. Voltage drop is reduced
DC cable runs introduce resistive losses proportional to length and inversely proportional to cross-sectional area. For a 500 metre run carrying 50A on a 35mm² cable, voltage drop can be in the order of 10 volt. The transformer rectifier must compensate by increasing its output, which means specifying a larger unit than the load technically requires.
3. Transformer voltage rating can be lower
Because the TR no longer needs to overcome cable losses, its output voltage requirement is reduced. A unit that might have needed to deliver 40V at the safe area position may only need 28V to 32V when installed in zone. Lower output voltage allows a smaller, simpler transformer with reduced manufacturing cost.
4. Operating power consumption is reduced
Energy lost as heat in long cable runs over the life of the system can be substantial. For a continuously operating 50A system, even modest cable losses translate to thousands of kilowatt-hours per year. Removing those losses lowers operating expenditure and improves the carbon profile of the cathodic protection system.
5. Commissioning is faster
Installation time on site is reduced because there is no cable trench, no ducting, no extensive cable pulls and no commissioning tests on long DC runs. The hazardous area TR connects to its local supply and to the anode groundbed within a much shorter physical footprint.
6. Total installed cost is lower
When the cost of cable, civils, labour and commissioning is compared against the marginal premium for ATEX , IECEx and UKEx certification, in-zone installation almost always returns a lower total project cost for medium to large systems. The savings are most pronounced where cable routes are constrained by concrete, structural steel or congested pipe racks.
7. Cost effective solutions
Hockway™ are licensed within certification to manufacture Multi channel Transformer Rectifiers that can combine different control Types in one unit offering multiple independent DC Outputs resulting in very cost-effective solutions for asset protection instead of having multiple individual Transformer Rectifier Units.
What Hockway™ offers
The Hockway™ hazardous area transformer rectifier range covers:
- ATEX , IECEx and UKEx certified models for Zone 1 and Zone 2 environments
- Output current ratings from a few amps to 150A and higher (up to total 25kVA)
- Air-cooled and oil-cooled configurations
- Thyristor and variac controlled output
- Standard and bespoke enclosure designs
- IP66 ingress protection certified to IEC 60529
- Multi Channel Options for all control Types combining multiple Independent DC Outputs In One Transformer Rectifier
- Remote Monitoring and Control System (RMCS) integration as optional.
Every Hockway™ transformer rectifier is engineered to the specific operating conditions of the project: high ambient temperature derating for Middle East and tropical climates, vibration and shock resistance for offshore platforms, and corrosion-resistant enclosures for marine environments. Units are manufactured in the UK, with quality controlled to ISO 9001:2015 and full traceability documentation provided.
Applications
Hockway™ hazardous area transformer rectifiers are specified into:
- Onshore oil and gas terminals
- Cross-country pipeline pump stations
- Refinery and petrochemical plants
- LPG, LNG and fuel storage tank farms
- Offshore platforms and FPSOs
- Process water and chemical storage facilities
A different range of safe area transformer rectifier units are used in non-hazardous applications where the operational benefits (compact footprint, robust enclosure, RMCS integration) justify the specification.
Standards and Compliance
Every Hockway™ hazardous area transformer rectifier is designed, tested and certified against the relevant standards:
- ATEX Directive 2014/34/EU
- IECEx scheme
- IEC 60079 series (explosive atmospheres)
- IEC 60529 (degrees of protection, IP66)
- ISO 15589-1 (cathodic protection of onshore pipelines)
- AMPP SP0169 (formerly NACE SP0169, control of external corrosion)
All Hockway™ units are designed by Corrpro Europe’s UK engineering team, with technical authority from AMPP and ICorr certified specialists.
Frequently Asked Questions
What is the difference between ATEX and IECEx?
ATEX is the European Union framework for hazardous area equipment, defined by Directive 2014/34/EU. IECEx is the parallel international scheme administered by the IEC. Both apply equivalent technical requirements, but IECEx is more widely accepted outside the EU and UK. Hockway™ transformer rectifiers can be supplied with ATEX, IECEx or both certifications depending on the project location. UKEx certification is still applicable and remains the official long-term framework for Great Britain, but it is no longer mandatory for most products due to a major government policy shift.
When do I need a hazardous area rated transformer rectifier?
A hazardous area rated TR is required whenever the equipment is installed inside a classified hazardous zone (Zone 0, Zone 1 or Zone 2) under the relevant area classification drawing. If the TR sits in a non-hazardous (safe) area and only the DC output cables enter the zone, hazardous area certification of the TR is not required, although specific safety requirements still apply to cable terminations.
What is the difference between Zone 1 and Zone 2?
Zone 1 is where an explosive gas atmosphere is likely to occur in normal operation, such as around vents and process areas. Zone 2 is where an explosive gas atmosphere is unlikely under normal operation but may persist briefly during upsets, typically the area surrounding Zone 1.
Does Hockway™ design transformer rectifiers for Zone 0 environments?
Zone 0 environments (continuous explosive atmosphere) are extremely demanding and typically do not house electrical power equipment. Hockway™ focuses on Zone 1 and Zone 2 specifications. Where Zone 0 protection is required, alternative architecture using a safe area TR with isolated DC supply is normally specified.
What gas groups and temperature classes does Hockway™ support?
Temperature classes T3 and T4 are standard, with T6 available where lower surface temperatures are required.
How long is the lead time for a hazardous area transformer rectifier?
Standard hazardous area Hockway™ TRs are typically delivered in 16 weeks from order. Bespoke configurations, large output ratings or special enclosure requirements may extend lead times. Confirmed delivery dates are provided after design review.
Specify Hockway™ for your next hazardous area CP project
Specifying a Hockway™ hazardous area transformer rectifier from Corrpro Europe places the cathodic protection power supply where it is most effective and avoids the long-term operational and capital costs of cable runs across hazardous plants. The full Hockway™ range is designed, manufactured and certified in the UK, supported by ICorr and AMPP certified engineers.
To discuss a hazardous area cathodic protection project, contact our engineering team or access technical datasheets for Corrpro Europe’s Hockway™ transformer rectifiers and remote monitoring and control solutions, including air-cooled, oil-cooled, and hazardous models here. Each document provides essential specifications to support selection, system design, compliance, and procurement for impressed current cathodic protection applications.
