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Case Studies

Enemalta Corporation

Enemalta Corporation is the main provider of energy generation and distribution in the Maltese Islands.  All of the electrical energy that is required in Malta is generated by the Enemalta Corporation.

The oldest power station (Marsa) in service was commissioned in 1966 and consists of the South Wales Switchgear (SWS) type EM12 and EM20, 33kV, 1000MVA indoor switchgear.  This product was a world leading product at the time and the originally named Malta Electricity Board’s decision to install the SWS type EM product has paid dividends, giving nearly 50 years of exemplary service.

However, in 2009, an internal flashover occurred in the 2000A bus section ocb, causing extensive damage to the ocb internals, ocb primary bushings and fixed portion bushings as shown in pictures 3 and 4 to your left.

Following recommendations from one of the UK’s leading consultants, Switchgear Support Ltd (SSL) were contacted to see if we could assist.  SSL assessed the situation from a series of photographs  and quickly informed Enemalta that we would be happy to refurbish the unit.  

Although we could have manufactured new primary bushings, Enemalta used some spare bushings to refurbish the fixed portion of the switchboard.  They also then issued six spare ocb primary bushings to assist in the refurbishment of the ocb.  These bushings had been held as spares for a considerable period of time and as such, moisture had naturally penetrated the bushings.  Once received in the UK, tan delta tests on the six bushings confirmed this. Over a period of four weeks, these bushings were cyclically treated/tested until successful tan delta test results were recorded, thus allowing them to be reused in the refurbishment of the ocb.

In addition to a thorough external clean up of the ocb and its frame, the following items were replaced with original design, certified components :

  • Fixed contacts          
  • Moving contacts       
  • Lifting bars    
  • Buffers              
  • Internally mounted CT’s       
  • Power solenoid coil
  • Tank interlocks           
  • Gaskets                
  • Umbilicals

Enemalta also provided us with a spare 1200A, EM12 ocb which reduced costs and timeframes by allowing us to use the ocb tank and arc control pots from this ocb (identical to the 2000A ocb).

Switchgear Support Ltd was quite possibly the only company in the world with the necessary skills and product knowledge to conduct these works.

Dave Johnson, Director of Switchgear Support Ltd, says “This contract certainly presented numerous challenges due to the rarity and age of the product.  But, from the gentle restoration of the spare ocb bushings, to the challenges of the full refurbishment and testing of the finished ocb, we had the total support and trust of Enemalta to allow us to complete the task in the quickest timeframe possible, so that the security of Enemalta’s network could be restored.  The contract was hugely satisfying in terms of success and achievement”

Peter Grima, Chief Technical Officer of Enemalta Corporation says “We were very impressed by the quality of the service and level of professionalism offered by Switchgear Support Ltd and following the repairs carried out on the circuit breaker, the switchboard is back in full service. I have no hesitation in recommending Switchgear Support Ltd for any such jobs.”