Diesel Generator Cooling Fan — Emergency Balancing at a Wind Farm

The Problem

A 2 MW wind farm in Andalusia, Spain relies on a backup diesel generator for grid-independent operation during maintenance windows. During a scheduled tower inspection, the generator’s cooling fan began producing a harsh metallic rattle at operating speed. Vibration on the fan bearing housing measured 18.2 mm/s RMS — deep into ISO 10816 Zone D (danger).

The generator was shut down immediately. Without backup power the crane could not operate, halting the entire maintenance schedule. The nearest replacement fan was in a warehouse in Bilbao — three days away by freight.

The Solution

The site electrician had a Balanset-1A in his toolkit, purchased six months earlier for motor maintenance. He had never balanced a generator fan before, but the single-plane procedure is straightforward.

Sensor installation took four minutes. One vibration sensor was magnetically clamped to the fan bearing pedestal. The tachometer reflective strip went on the shaft coupling — no disassembly required.

Reference run. The generator was started and allowed to stabilize at 1500 RPM. Balanset-1A recorded 18.2 mm/s RMS with a clear 1× peak confirming imbalance. The phase reading was stable — no looseness or resonance complicating the picture.

Trial weight. A 15 g clip-on weight was placed at the 0° mark on the fan hub. Second run: vibration dropped to 9.4 mm/s and phase shifted 137°. The software calculated the correction vector instantly.

Correction. 22 g welded at 215° on the fan rim. Final measurement: 2.1 mm/s RMS — comfortably in Zone A.

The Outcome

Twenty-five minutes from first sensor clamp to final verification. The generator restarted, the crane resumed lifting, and the tower inspection finished on schedule. The replacement fan from Bilbao arrived three days later — and went straight to the spare-parts shelf.

The site manager estimated the avoided downtime at roughly €12,000 in lost generation and contractor standby fees. The Balanset-1A had paid for itself on this single intervention.