The Federal Energy Regulatory Commission said it has more questions for NYISO before considering proposed revisions to its rules for retired and mothballed generators.

FERC last week sent NYISO a deficiency letter (ER14-2518) listing questions about the ISO’s July 2014 proposal, which would allow it to terminate a generator’s eligibility to participate in the Installed Capacity (ICAP) market after six months in a forced outage if repairs have not been started.

The proposal also would add Tariff definitions of the terms “mothball outage” and “retired.”

The Independent Power Producers of New York supported the six-month rule for participating in the ICAP market. However, it said FERC should reject a requirement that generators on outage respond to reliability needs by returning to service or making their interconnection points available. The association said the requirement would deny generators rights they earned in interconnection agreements with transmission owners.

Responding to the objections, NYISO said in September that “Any modification to, or termination of, an existing interconnection agreement … will continue to be subject to the terms and conditions of the underlying agreements.”

On Jan. 29, FERC’s Office of Energy Market Regulation gave the ISO 14 days to reply to additional questions, including whether it intends to apply its definition of “retired” generators to those with existing interconnection agreements. FERC also asked whether the ISO could unilaterally terminate the interconnection agreements of units in retired status.