Location #
Transformer Rectifiers can be of several specifications including combined, separate transformers and rectifiers assemblies, indoor or outdoor. Suppliers would not have a difficulty with any of these requirements either ONAN or ANAF.
A problem however has been experienced when the installation is in a hazardous area. A supplier would by preference then supply a purge pressurised enclosure EEXp which does not always prove acceptable to project specifications.
In the preparation of an enquiry or in the evaluation of a technical proposal it is advisable to avoid specifying explosion proof enclosures EExd. These are generally unavailable in the requisite sizes and do not readily lend themselves to dissipation of the heat generated in the transformer and rectifier assemblies..
With any rectifier installation there is the question of harmonic distortion to the supply utility. Experience has shown that this has not proven to be a significant problem and an agreement to install supply filters retrospectively should any problem occur in practice has been an argument satisfactory to most parties during bid clarifications.
Interconnecting Conductors #
Another consideration is the proximity of the Transformer Rectifiers to the Electrolysers. The DC output of the Transformer Rectifiers is of low voltage and high current and any voltage drop in the interconnecting conductors will reflect in the product DC kWh/kg.
Typically a supplier would target approximately <=1 VDC loss between the T/R and the electrolyser to minimise the effect on the overall DC kWh/kg. In an installation where the T/R is remote to the electrolysers this would entail for example larger bus bars than ampacity or cable tables may suggest as suitable, increasing cost significantly.
Therefore for example when a EExp T/R local to the electrolyser is unacceptable and a remote safe area T/R is installed the trade off on the interconnecting conductors has to be taken into the design and cost considerations.
