Plant & Works Engineering
Cutting costs and keeping safe
Published:  04 June, 2015

PWE looks at how the inclusion of thermal imaging windows reduces inspection costs and makes maintenance smarter, without increasing health and safety risks. PWE reports.

‘Caution, keep this door closed’ is a sign most maintenance engineers will encounter on electrical switchgear cabinets. This warning alerts them to the serious prospect of arc flash that has the potential to cause serious and even fatal burns. As a result there are two options.

The first option is to shut down the electrical system so that a team of electricians can remove the panel and inspect the components. The drawback is that this solution only allows faulty components, such as terminals, to be identified. As the system isn’t under load there is no possibility of assessing, for example, the heat rise in a bus bar.

The second option is to leave the system under load; have the team of electricians suit up in full PPE and then remove the panel and inspect the components. While this option obviously allows the electricians to better assess what may be wrong, it also exposes them to extremely hazardous conditions that could cause an arc flash explosion resulting in severe or even fatal injuries.

It was for this type of regime that CTS – Combined Technical Solutions, which carries out all aspects of work related to built environments including both reactive and planned preventative maintenance, had been engaged by a client in central London. Electrical inspection was undertaken during annual shutdown and although the systems continued to work well as a result of its diligence, CTS recognised the potential pitfalls.

Safe, live inspection

An increasingly preferable solution for many companies is predictive maintenance using thermal imaging and in this instance, IRISS polymer infrared (IR) windows were selected. These provide data collection points that keep the thermographer safe while allowing him or her to inspect the fully energised system, obtaining both quantitative and qualitative information. And this is precisely the plan that CTS proposed to its client.

The choice of IRISS’s polymer IR windows was based on suitability for the job and cost. Crystal windows were considered but dismissed for several reasons. Firstly they carry a significant risk of breakage, even an electrician slamming an enclosure can cause a crystal window to shatter. In contrast an IRISS window has an unconditional lifetime warranty against breakage. It is reinforced by an aluminium honeycomb grill and is resistant to moisture, humidity, vibration and high frequency noise.

Cost was another factor. IRISS highlights that its windows outlive crystal alternatives and are also cheaper. Additionally the manufacturer says it also offers custom solutions, where it configures its polymer IR windows to any shape or size, a capability that is not achievable with crystal technology. This means a window can be supplied, for example, that allows the inspection of a busbar or multiple components in a single pass of the camera.

The business case that CTS presented to its client, for installing twelve IRISS VPFR windows on switchgear cabinets, was compelling. The client would achieve the best of both worlds; substantially reduced risk of system failure and lower maintenance costs. As a result 12 windows were installed, a process that was completed over a weekend.

“By installing IRISS windows we can now carry out inspection while the systems are live but in a safe and guarded condition”, explained CTS director, Kim Harris. “As the process is not intrusive it presents minimal risk to business operations and the health and safety of employees.”

He continued: “And as we can now inspect these electrical systems during normal working hours, instead of during an electrical maintenance shut down, the cost to the client has also been reduced. The payback, in monetary sense, has been almost immediate. Also the new regime will allow us to inspect systems that were considered too risky as their incident energy calculations exceeded PPE ratings.”

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