By Rudy Wodrich, VP of Engineering Services
“Low Voltage” typically means higher current, and higher current means higher “I-squared R” losses in conductors. It also means a higher likelihood that the transitions where one conductor type meets another will, due to load induced thermal cycling and slightly different coefficients of thermal expansion of dissimilar materials, loosen over time and become even higher resistance. Left unchecked, this increases system losses and decreases electrical system efficiency. It will also lead to overheating and failure of the connection, with unscheduled downtime and expensive repairs being the result. By far, the best way to detect these loose connections is by using infrared thermography. The most common places we see problems are where multi-strand cables land in fuseholders and circuit breakers.
It is our estimation that 60% of electricity in industrial and commercial buildings passes through a LV switchboard before eventually getting those electrons down to the point of use, where they are converted into heat, light or magnetic fields and motion. Switchboards are full of circuit breakers connected to the power cabling that then feed out to the various loads. This makes for A LOT of potential points of failure all in one electrical asset and makes it critical that these connections are periodically inspected. However, doing so safely and economically is a challenge because the connections in question are behind enclosure panels that we can’t see. Thermography requires line of sight to the targets and must be done with the equipment energized and under “normal” load conditions, but we also have to follow the rules of keeping equipment closed and guarded whenever possible. NFPA 70E strongly discourages any kind of open panel energized work, even with the proper PPE. So, how to overcome this conundrum?
For one very common design of Switchboard, the Square D (by Schneider Electric) QED2 Switchboard family, IRISS has developed a range of custom replacement panel solutions for just this purpose. QED2 is configured with breakers in single or double vertical stack with sheet metal gutter covers. For single stack lineups, the Left Hand gutter cover conceals the load side cabling coming off of the breakers – these are the connections we want to be able to IR scan. For double vertical stack lineups, both the Left and Right Hand gutter covers conceal the connections we want to monitor. There are about a dozen different standard widths for these gutter covers and IRISS has FlexIR replacement panel designs for all of these but that then include a full height Infrared viewing pane and latching cover. Installation of the replacement panels can be done in a matter of 3-4 minutes and the replacement panels are fully UL Listed as enclosure accessories and enable IR scanning of the cable connections.
In addition, you may find that sometimes you have small frame breakers that make up part of the vertical stack and they are equipped with a blanking plate that snaps into the backside mounting rail of the gutter cover. These blanking plates cover the small frame breaker cable connections but IRISS has developed replacement QwikFit blanking plates that are IR transmissive with a special IR polymer and IP2x compliant touch-proof grill. QwikFit Blanking plates are available in two sizes for both standard breakers and breakers with electronic trip units and snap mount in the same way as the factory original plates.
Both FlexIR replacement panels and QwikFit blanking plates are very economical, install in minutes and simple to size for your QED2 application. IRISS also has designs available for older models of Schneider Switchboards, I-Line Panelboards as well as for other OEMs including Eaton and Siemens. For more information and pricing, please contact us at email@example.com or by calling (941) 907-9128 and asking for sales & technical support.
By Drew Walts ARP-1 SME, LV2 ASU, LV2 IRT
Be Safe! Never make contact on energized equipment with an ultrasound device!
Growing up working for my father’s construction company, there was one saying he use to say, “Just because you can, doesn’t mean you should!”. This was usually dad’s go-to statement when talking to one of his guys on the jobsite when they did something unsafe or risky. Today, this adage still applies and even more so when it comes to electrical inspections with ultrasound devices. Just because you have a contact module in your kit, doesn’t mean you should use it to contact energized gear when you hear something with your airborne module from the seam, vented opening, or ultrasound port!
If we look to the Hierarchy of Controls from NFPA 70E, the first step is the Elimination of the hazard by de-energization of the equipment. However, Condition Based Maintenance (CBM) inspections like ultrasound require the equipment to be energized and so we move to the second stage called Substitution or “Safety by Design”. The question is can we redesign the work task and/or the equipment in such a way as to eliminate the hazard without introducing any other new hazards. The use of Infrared Windows and Ultrasound Ports is the best method for Substitution of the in the CBM realm since Infrared and Ultrasound have become a go to test method for the detection of electrical fault conditions of closed panel energized assets.
Without the Substitution (Safety by Design) Devices in place, it can be next to impossible to test using Infrared Cameras or Ultrasound Devices. With the enclosure panels in place the inspector may still be able to use an airborne module and trace the seams or air vents to listen for ultrasound anomalies. Remember that most electrical equipment should have no discernible noise emanating in the ultrasound spectrum. In addition, the challenge with this “seam sniffing” method is that diffraction of the signal can cause issues with the signal’s amplitude being increased as it bounces out of the seam and increases the decibels. Decibels should never be used as a trendable value for determining required intervention action on electrical assets. Sound wave analysis of the anomaly is the only way to truly determine what fault condition is present in the gear.
When ultrasound is detected coming from the asset, it should be tested further, but with the panel being closed and without having IR Windows or Ultrasound Ports there is no way to safely test this while energized. So, the gear will need to be de-energized and then opened to look for visual indications of corona, treeing or tracking. Once these visual indications are found, corrective action can be determined which may include cleaning, component replacement or re-cabling.
1 in every 10,000 at risk behaviors in the Electrical World will end in a fatality
The inspector should almost never perform an open panel energized inspection using ultrasound devices or infrared cameras, as this would be deemed a last resort per the Hierarchy of Controls. In the event that this is deemed the ONLY way to perform the work, the personnel have the appropriate training, a job safety plan has been created (including planning for human error) and if the equipment’s arc flash rating has been gauged to be one that PPE can be worn to perform energized open inspections, there are still a few things that will need to be heeded.
- The CBM Analyst should never wear the head phones for their ultrasound device under the hood of the Arc Flash Suit, but rather hold the head phones of to the side by their ear on the exterior of the suit.
- Even when wearing PPE, they should also never break the plane of the opening of the gear. Restricted approach boundaries as defined in the NFPA 70E tables [130.4(D)] should always be maintained.
- They should especially never use the contact module or even rubber / plastic focusing probes or range horns to touch energized equipment to locate or listen to the anomaly. It only takes one time for it to be your last time ever!
So, a CBM Technician should only very rarely open gear while it is still energized to perform an airborne ultrasound inspection. It has been brought to our attention that there are instances where a CBM Technician has actually swapped out their airborne module and used their contact module to make physical contact with open energized gear and we cannot stress enough that this is an unsafe act and should never be done!
We at IRISS cannot stress the importance of safety for electrical personnel enough and this is why we created the IR Windows and Ultrasound Ports to help protect those doing electrical inspection by minimizing the risk of this CBM data collection task. Being able to visually look with your eyes and IR Camera affords you a safer view of what’s occurring inside the equipment and the addition of the Ultrasound Ports give you the best sound quality of any possible electrical anomaly without the effects of Antagonistic Ultrasound, Diffraction of Signal or inability to achieve the Critical Angle of the anomaly.
About IRISS Inc.
IRISS Inc. is the global provider of Electrical & Mechanical Asset Management Solutions that increase safety and reliability, while decreasing costs, human error, and injuries/fatalities in the inspection and maintenance process. Through unmatched research and development, we harness advanced technology to design and manufacture reliable Infrared, Ultrasound, Intelligent Asset Management, and Wireless Temperature Monitoring solutions.