* Q3 rev $18.1 mln vs est $16 mln

* Sees Q4 loss/shr less than $0.39 vs est. $0.27

* Shares down as much as 12 pct

By Bijoy Anandoth Koyitty

Feb 9 (Reuters) - AMSC posted its fourth straight quarterly loss and gave a lower-than-expected outlook, as it continues to reel under the loss of its biggest customer China's Sinovel Wind Group with no respite in sight.

Shares of the company, which makes the core electrical systems used in wind turbines, fell as much as 12 percent to a low of $5.32 in morning trade on the Nasdaq.

The company, which used to derive 90 percent of its revenue from China, hit a lean patch in mid-2011 when its troubles with Sinovel began. Since then its revenue has shrunk more than 70 percent and its shares have lost 90 percent of their value.

AMSC forecast fourth-quarter adjusted loss of less than 39 cents a share, with revenue exceeding $27 million. Analysts were expecting a loss of 27 cents a share, on revenue of $31.3 million, according to Thomson Reuters I/B/E/S.

On a conference call with analysts, AMSC said it expects to continue to have "slightly" negative gross margin for the fourth quarter, mainly due to accounting issues and the timing on some contracts.

On the call, AMSC also said it is exploring financing options to help it make additional investments, but added that it has sufficient cash to fund requirements for at least the next 12 months.

Last November, AMSC sued Sinovel for stealing intellectual property and violating a contract. It is seeking to recover more than $1.2 billion from Sinovel through civil cases filed in various Chinese courts.

FIXING LOOSE ENDS

AMSC's overwhelming dependence on Sinovel had always been a concern for investors, and since the break-up AMSC has been scouting for new customers and markets.

Factbox on AMSC customers

For the third quarter, AMSC said its largest customers were India's Inox at 27 percent of revenue. Korea's Doosan Heavy Industries accounted for about 12 percent.

AMSC, founded by Greg Yurek in 1987 with three fellow Massachusetts Institute of Technology professors, also revamped its business segments, corporate identity and named a new CEO in late 2011.

In November, it laid off more than a fifth of its workforce.

Shares of the company, which have gained more than three quarters of their value after touching a year-low in October, were down 9 percent at $5.53 in mid-day trade.

• A Permanent Economic Emergency