UPDATE 1-RWE puts off Emsland reactor restart again

* New delay to likely reopening indicated

* RWE says fixed problem, sees ball in supervisors' court

(adds new date, RWE comment)

FRANKFURT, July 28 (Reuters) - German utility RWE (RWEG.DE) has put back the targeted restart of its Emsland nuclear reactor in northern Germany by another one or two days, the third envisaged delay to reopening after the unit went offline on July 24, its website showed on Tuesday.

A spokesman for RWE's power generating unit said a faulty switch had been swapped for an alternative part, which now needed approval from nuclear supervisory authorities.

The 1,400 megawatts plant in the state of Lower Saxony is now seen back online between July 30 and August 1, rather than between July 28 and 30, and between July 27 and 29, which were indicated at earlier successive stages.

The company's transparency website operates in real time with constant input from the plants' management in order to inform the wholesale power market about likely supply and demand.

Last Friday, the 11-year old plant went into an unplanned outage as a transformer switch did not function fully, leading to the separation from the high voltage distribution grid.

The operator at the time expected the problem to be resolved within a day or two.

Once the authorities give their go ahead, RWE will test the new part and then recommission the overall plant, said RWE Power spokesman Manfred Lang.

"Talking from experience, these steps do not happen overnight," he said.

The problem comes at a time at which Germany's nuclear power plants are in the spotlight ahead of national elections on Sept. 27.

The anti-nuclear Social Democrats share power with Chancellor Angela Merkel's conservatives.

They have used a recent series of unrelated nuclear problems -- not uncommon during the summer maintenance season -- to highlight perceived safety risks which led to an exit programme.

By contrast the conservatives, forced to go along with the phase out deal agreed in 2001, will prolong the running times of those plants judged safe if they win a majority.

(Reporting by Vera Eckert)