Generator failures foil CUC

A series of unexpected generator breakdowns has been the main culprit of Caribbean Utilities Company electrical power failures in recent months.

CUC brought in four portable generators this week to help bridge the gap until all of the broken generators can be fixed or replaced.

CUC President and CEO Richard Hew said all three of the generators broke down in December leading to power failures for certain customers.

‘Whenever we’re running with tight [capacity to demand] margins and we lose a generator – which happens from time to time – we’ll have to shed some customers,’ he said.

Two of the generators that failed were 10MW units that were about 20 years old. One of those generators had an electrical failure and is still inactive while CUC waits on a part that will arrive in six to eight weeks.

The other 10MW generator is running, but at only at about 70 per cent capacity. That generator had a mechanical failure of a vibration damper, however the replacement part CUC had in stock was not the right size. Thus the generator has been de-rated until the new part arrives, which could be as late as September.

The third generator that failed was the new 8.4MW gas generator that was delivered after Hurricane Ivan. That generator was primarily used as a back-up, and Mr. Hew said the manufacturer has not figured out why it failed.

However, the generator was still under warranty, so the module that failed has been shipped back to the manufacturer in Germany for replacement.

‘We’re hoping to have it back here by the end of the month,’ he said.

The breakdown of the two 10 MW generators had a silver lining, Mr. Hew said.

‘We took the opportunity, while they were down, to go through them thoroughly,’ he said. ‘They’re actually in very good condition. They’re good for many, many more years.’

Having two generators down and another one temporarily de-rated has forced CUC to run its other generators longer than scheduled.

‘After what happened in December, we’ve been running the units that are available,’ said Mr. Hew. ‘We can’t afford to take them off line to do scheduled maintenance.’

The four 5.6 MW temporary generators that arrived this week will allow CUC to start getting back on track for its maintenance schedule. Bringing in the temporary generators from overseas was not something CUC wanted to do – it just returned the last four it had leased in response to Hurricane Ivan damage last November – but it was something it realised it needed to do.

‘Our objective is to be ready for the summer,’ Mr. Hew said.

There is more help on the way for the long term as well. CUC has a new 16MW generator due here in April, for commissioning in July. Once that generator goes on line and the other three are repaired, CUC will have enough generating capacity to meet estimated demand through 2010, Mr. Hew said.

But the generators haven’t been the only reason CUC customers have experienced some power outages. There have been some transmission and distribution problems due to equipment failures and mechanical failures.

‘Most of [the problems] are remnants of the hurricane,’ Mr. Hew said. ‘Some of it is salt corrosion. Some of it is physical damage, like cracked insulators.’

Even though CUC does annual visual inspections of all of its lines, there are some of the problems cannot be easily seen visibly, Mr. Hew said.

The company is now using infrared thermography devised to detect its T & D equipment. It has also increased the frequency of its inspections significantly especially in problem areas like Savannah and the south coast.

‘The challenge is we have more than 300 miles of lines, 14,000 poles, 4,000 transformers and thousands of insulators, many exposed to 150 mph winds and wind-driven salt,’ Mr. Hew said.

However, CUC is committed to addressing the problem. Even though it had a system availability rating of 99.92 per cent last year, it knows its customers want that figure even higher.

‘Based on surveys done in the industry, it’s accepted that customers want, first and foremost, reliability.’

Mr. Hew said customers also want stable prices and low average prices.

‘We have more control over reliability than prices because of the fuel costs,’ he said.

Going into the future, Mr. Hew is confident that CUC’s reliability will get better.

‘As we go on in time, I think these random [power] failures will decrease,’ he said.

Starting this month, CUC will commence a capital project that will help its reliability significantly in the long run. That project will link CUC’s Frank Sound substation with the temporary substation in Rum Point, which in turn links back to the CUC plant via the submarine cable through the North Sound.

Once that project is completed in a year to 18 months, an electrical power loop will exist on Grand Cayman so that if a failure were to occur due to line problem in South Sound, for example, all of the Eastern Districts will no longer be affected.