RWE Npower renovates ABB actuators at Tilbury

The actuators have outlasted the typical service life of most similar equipment and their long-term reliability played a key part in the decision to opt for refurbishment rather than renewal.

Frank Gamble, a control and instrumentation engineer, said: 'The electric actuators were originally purchased from Hartmann and Braun, but they're now ABB products.' Hartmann and Braun became part of the ABB family in 1999.

The gearboxes at the heart of the refurbished units remain the same, but the separate amplifiers that used to drive the actuators are now obsolete, so ABB has replaced them with new motors and electronics.

Tilbury is a coal-fired power station next to the River Thames.

It can generate more than 14,000 MW of electricity, enough to serve 80 per cent of the population of Essex.

One of the site's original four generating units was mothballed in the late 1990s and this made scheduling the actuator refurbishment work relatively easy.

Gamble said: 'We effectively had a spare set of actuators.

'First we sent these for refurbishment and then we swapped them onto one of the live units during the next planned overhaul.

'It's a rolling programme, with two out of three units now complete and the third unit due for completion during a planned overhaul in April 2008.' The refurbished actuators cover a wide range of sizes and applications.

Gamble added: 'For example, turbine speed control is a demanding application in which the actuator is moving all the time.

'Others are outdoors and exposed to the weather, but they've been very reliable over all these years.' All ABB actuators offer continuous control with a virtually wear-free operation, as well as high positioning accuracy and stability, regardless of positioning time.

Even continuously operating ABB actuators can perform maintenance-free for long periods, making them ideal for industries such as power generation, in which plants typically operate for extended intervals between shutdowns.