A Unic Mini Spider Crane Lifts Silencers at Power Station

A Unic mini spider crane provided lifting power at the National Grid’s East Claydon electrical substation in Buckinghamshire, UK.

The 10t capacity crane was hired from GGR Group to lift 16 silencers which reduce the operating noise coming from the 400kV substation’s air blast circuit breakers. 

The URW-1006 has 30.7m maximum lifting height despite being just 2m wide when stowed. The largest mini crane in the Unic range was chosen for this complex job as it had the reach required to lift up and over the power lines. The power was switched off on the circuit, and the adjacent circuits, for this specialist lifting operation.

Silencers are used as the noise is deafening when the circuit opens and the arc is extinguished by a blast of air. They need to be regularly removed and replaced for cleaning and essential maintenance. In the past this task has been completed using a larger crane working from the roadside, which requires a higher capacity and bigger working radius. Thanks to the compact size of the mini crane, it was able to work inside the substation and safely around high voltage power. 

A practice run was undertaken to make sure the crane’s boom was set to work at the right radius. GGR‘s operators, who are BESC, EUSR and CPCS qualified, used the Unic URW-1006 to remove each of the 50kg silencers.

While the crane operator accurately controlled the spider crane using a radio remote control, the slinger/signaller worked from an access platform to securely sling each of the silencers ready for lifting.

The crane lifted each silencer to a 16m height, working at a 11.5m radius. Unic mini cranes feature a working area limitation function which makes them ideal for use in restricted zones such as this where working parameters need to be set.