Electrochlorination is used to generate sodium hypochlorite on site by applying direct current to an electrolytic process.
The transformer rectifier unit is therefore an essential part of the EC package. Its configuration influences electrical performance, integration, cooling, installation and long-term serviceability.
Selecting a suitable transformer rectifier requires more than providing a maximum current and voltage. The power system must be engineered around the electrical requirements of the process and the conditions at the installation site.
Below are the most important topics to define at the beginning of the project.
1. Define the required electrical performance
The customer or system integrator must first define the electrical parameters required by the electrochlorination process.
These normally include:
- required DC current
- required DC voltage
- operating range
- load profile
- allowable ripple
- operating hours
- required control accuracy
- expected process variations
These values form the basis for the transformer rectifier design.
plating electronic does not determine the process capacity of the complete electrochlorination system. Instead, the transformer rectifier is engineered based on the technical performance requirements provided by the customer or system integrator.
2. Select the appropriate SCR configuration
SCR technology is suitable for project-specific transformer rectifier systems used in demanding industrial environments.
Depending on the application, the system can be configured with:
- oil cooling
- water cooling
- 6- or 12-pulse rectification
- additional smoothing equipment
- project-specific control systems
- indoor or outdoor enclosures
A 12-pulse configuration can achieve ripple values of up to 3.5%. Where the process requires a lower ripple level, additional smoothing devices can be considered.
The final configuration must be evaluated against the process requirements, installation conditions and total system design.
3. Clarify indoor, outdoor, onshore or offshore installation
The installation environment has a major influence on the enclosure, cooling concept and material selection.
For an outdoor or offshore application, the project specification may need to define:
- ingress protection
- ambient temperature
- humidity
- salt exposure
- corrosion category
- enclosure material
- coating system
- ventilation
- cooling-water conditions
- accessibility for maintenance
Depending on the project, transformer rectifier systems can be designed with protection up to IP66 or NEMA 4X, ambient temperatures up to 50 °C, stainless-steel construction or C5-M coating.
These options are project-dependent and must be confirmed for the individual application.
4. Determine whether hazardous-area requirements apply
Terms such as Zone 1, Zone 2, ATEX and IECEx should be discussed early in the project.
It is important to determine:
- whether the transformer rectifier is installed inside the hazardous area;
- which zone classification applies;
- which gas group applies;
- which temperature class is required;
- which protection concept is expected;
- which components must be certified;
- whether certification applies to the TR/TRU or the complete EC package;
- which party is responsible for the overall certification.
plating electronic can engineer project-specific transformer rectifier systems for requirements associated with Zone 1 and Zone 2 installations.
However, the exact certification scope must be defined and obtained for each individual project. It should not be assumed that a standard off-the-shelf unit already covers every hazardous-area requirement.
5. Define the control and communication concept
The TR or TRU must communicate with the wider electrochlorination package and, where applicable, the plant control system.
The project specification should therefore identify:
- required control mode
- local or remote operation
- fieldbus connection
- communication protocols
- status signals
- alarms
- interlocks
- emergency shutdown signals
- fault handling
- data logging requirements
Industrial interfaces can be selected according to the customer’s control architecture.
Early coordination between the power-system supplier and system integrator helps prevent interface problems later in the project.
6. Define responsibilities for integration
Clear responsibilities are essential in complex EC projects.
The project team should agree who is responsible for:
- process sizing
- electrolyzer specification
- transformer rectifier engineering
- cooling-system design
- electrical installation
- mechanical installation
- hazardous-area assessment
- package certification
- control-system integration
- FAT
- SAT
- on-site commissioning
- offshore commissioning
- long-term service
plating electronic supports product-related engineering, technical documentation, coordination around the transformer rectifier system, onshore commissioning, service and spare parts.
Start with a complete technical specification
A reliable transformer rectifier concept starts with clearly defined requirements.
The customer or system integrator should provide the required electrical performance, environmental conditions, hazardous-area classification, control interfaces and project responsibilities.
Based on this information, plating electronic can engineer a project-specific SCR transformer rectifier system for integration into the electrochlorination package.
