Hawk’s eye hones in on cement production

01 November 2007

Hawk IR has used infrared sightglasses to discover faults in motor starters at a cement plant.

Thermal image showing high resistance contact on right compared to the left

The UK based infrared safety specialist advised on a sightglass installation at a cement plant where the electrical distribution system is made up of 11KV, 3.3KV and 415V, with most of the larger motors operating at 3.3KV.

A typical motor starter installation consists of a motor, local isolator and motor control centre (MCC). The motor starter utilises standard 110V control circuits with protection relays to control a vacuum contractor.

During routine maintenance inspection of a 3.3KV motor starter, evidence of a high resistance contact was noted in the form of discolouring on the fixed stab contacts. The cause could not be identified whilst the system was not energised and under load.

Two 75mm C-range Hawk IR sightglasses were installed so a thermographic (IR) inspection could be carried out in total safety without opening the panel and with the system under full load.

The survey indicated a high resistance contact, the root cause of which was identified as a deformed contact spring.

Following re-alignment the inspection was repeated and a significant reduction in heat was noted.

Subsequently additional drives were fitted with Hawk IR sightglasses, and similar alignment problems were identified on four other motor starters.

As a result of the concerns raided by the discovery of these faults that could lead to failure and production loss, a further 160 Hawk IR C-range sightglasses have now been installed in electrical equipment controlling fans, pumps, transformers and compressors.