Transformer Uprating

Transformer uprating is more cost effective than purchasing a new unit. It minimises disruptions to site operations and increases expected useful working life.

Distribution & Power Transformers can be modified and uprated to take increased load potential by maximising the efficiency at which excess heat is dissipated from the main core and windings. By completing thermal investigations to identify top oil rise, average winding rise and hottest spot temperatures, TP Power Services will design modifications for the transformer to operate safely at a higher rating in line with temperature rises set out in BS EN 60076 (2000) and IEC 76. All sizes of units can be uprated and sometimes by as much as 60% by implementing a number of progressive design methods to increase cooling efficiency whilst safeguarding integrity.
Natural Oil and Air (ONAN) Natural convection moves warmer oil to radiators for cooling by natural air flow at ambient temperature
Forced Air (ONAF) Cooling fans or heat exchangers increase the rate of cooling in radiators but oil still circulates naturally
Forced Oil (OFAN) Oil circulating pumps forces oil away from the core and windings but still relies on cooling by natural air flow
Forced Oil and Air (OFAF) Pumping oil away from the windings to radiators for cooling by forced air flow is the most efficient option

The majority of work to uprate a transformer is in the design, planning and procurement stages hence there is minimal impact on site operations as thermal inspections and measurement can be completed while units are still energised by trained engineers. Site works to install and test new equipment take on average 2 to 5 days to complete dependant upon the desired rating and existing transformer design and can be completed within a maintenance outage.

  • Radiators replaced with modern fin-type or more added to increase cooling surface
  • Installation of heat exchangers
  • Installation of radiator mounted axial cooling fans and mounting frames
  • Supply & Installation of tank mounted and free-standing heat exchangers
  • Installation of uprated or new oil circulating pumps and modification to pipework
  • Modifications to existing marshalling kiosks to incorporate new equipment
  • Supply & installation of cooling control kiosks and cable support systems