The LIPA Newbridge Road substation in Levittown being upgraded in 2006....

The LIPA Newbridge Road substation in Levittown being upgraded in 2006. Transformers at the substation handle power brought in from the undersea Neptune Cable.  Credit: Newsday/Jim Peppler

A week after the Cross-Sound Cable was restored following equipment problems, the Long Island Power Authority on Tuesday confirmed that another, larger undersea cable to Long Island has been having land-based problems that will reduce its capacity by half until 2022.

The Neptune Cable, which connects mid-Atlantic power sources to the LIPA grid, is operating at about half its 660-megawatt capacity.

In a statement, LIPA said the cable has been experiencing "intermittent outages due to problems at the New Jersey and Long Island substations" on land. It first experienced a transformer failure on the Long Island side of the cable beginning September. Then it experienced a New Jersey substation failure on Dec. 31, LIPA said.

As was the case in 2012, when the Neptune cable was partly out of service for more than a year, a large transformer failed at the Long Island substation. And while a new equipment has been ordered it’s not expected to be available until early 2022, LIPA said.

Interruptions appear to have begun at the end of November, according to data posted by the New York Independent System Operator, which manages the state grid. Problems appear to have been corrected for most of December, but reports show little activity on the cable since Dec. 31.

Last time there was a transformer problem, LIPA ratepayers had to foot a bill of some $40 million, including for replacement equipment and the cost to buy replacement power elsewhere. LIPA also had to pay agreed-upon capacity costs for the cable, even though it wasn’t being fully used, because the problems were on the land-based grid, not the cable itself.

The Cross-Sound Cable, at 330-megawatts, had been out since July before being restored last week, LIPA said. It connects to the New England grid via a cable beneath the Long Island Sound that connects at Shoreham.

LIPA said it has "sufficient excess capacity" to operate the system during the peak 2021 summer without the Neptune cable’s full 660-megawatt capacity.

The 65-mile-long Neptune cable travels under the Atlantic Ocean from Sayreville, New Jersey, to Jones Beach and then north to New Cassel. It provides a link to generally lower-cost power from the mid-Atlantic market, called PJM, and was completed in 2007 at a construction cost of more than $600 million.

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