We are starting to get questions about the use of Infrared Windows or ports for inspection of electrical gear.

What the main considerations for use?

Why don't the original manufacturers offer switchgear etc... with the IR windows factory installed?

Are any new hazards introduced as a result of installing an infrared window?

Thanks
Terry O

There is a lot of interest at the moment in infrared windows, I feel this is being stirred up by the sometimes agressive marketing campaigns of the manufacturers.

Why don't the original manufacturers offer switchgear etc... with the IR windows factory installed?
I dont know, but sometimes I think that mabey they know something we dont. I do believe that it is them the ir window manufacfturers should be marketing to and not us as thermographers. I do know that sometimes there are problems when retrofitting these to switchgear, especially if the switchgear is type tested. Manufacturers have told me that the fitting of these invalidates the type testing, and if this is the case it is not something that can be resolved. Mabey one of the ir window manufactures will enlighten us here.

Are any new hazards introduced as a result of installing an infrared window? Window manufacturers will of course say no and quote lots of approvals. In reality it depends on the type of window chosen and if it has been fitted correctly, the approvals will apply to the window and not the individual fitting on site. If they are not fitted correctly then I assume there is a risk of a failure during an arc flash. And we all know that not every item is installed correctly.

We looked at these several years ago and they were too expensive to consider at the time.

Another option is the fisheye lens with Mikron. The installation cost per panel is much cheaper. A different approach to the problem than the windows.

Safety sounds like a big issue and I suspect some systems better than others. I haven't gotten through all the info to form an opinion myself. I am hoping to learn enough to make a decision on these for our plant in the near future.

There has been a lot of animated discussion on this subject amongst vendors at the Snell infrared message board.

Pete,
I agree that the fisheye is awesome and gives a 45% view in all directions. The draw back is the cost. The ports for the lense are much more afordable than other windows, however the lense is very very expensive and is only good if you have a Mikron camera. If you have a Flir you are not going to be able to use it.

Hello,

I will try and answer as many questions as possible, without being commercial;

First of, switchgear manufacturers. The simple reason switchear manufacturers do not install the IR Sightglasses/Windows as standard is frankly "money". If the customer doesn't ask for it, they don't provide it, regardless of how useful it may or maynot be. As a manfacturer we can market our products to switchgear manufacturers all day, but unless the customer asks, they don't install. This is an unfortunate but harsh reality and applies to every potential addition, not just IR Sightglasses.

Second, IR Sightglasses or Ports need not be expensive. There are Mesh type ports on the market at $60USD that require no special lenses and will operate with any IR camera prices run upto around $350 for a blast tested, crystal version.

Third, Arc-flash. It is important that an IR Sightglass is at least subjected to the forces of an internal arc in order that its use and hence operational risk maybe accurately assessed. Without arc-tests it is not possible to attempt a prediction relating failure modes.

Fourth, be careful. It is important to check what manufacturers are telling you as carefully as possible, do not take things at face value. For example, a low cost polymer IR Window product using a thin-film polymer as a tranmitting medium had its UL Recognition retracted this week as the products were not manufactured in accordance with UL requirements in addition to concerns with the optic under a fault condition. This has left a lot of folks out there with products installed that are not UL Recognised even though they bare the UL mark.

I hope this helps a little, if anyone has direct questions please do ask. If there are any Hawk IR specific questions, please email me in order to keep this forum non-commerical.

Thanks and best regards,


Tony Holliday
Hawk IR International Inc.
TOLL FREE: 1-877-4-HAWKIR
Email. tony.holliday@hawk-ir.com
Web. http://www.hawk-ir.com

I'm not sure what voltage level is in question on this thread.

I had the chance to discuss this question with a switch gear designer at one of the major international switch gear design/manufacturing companies.

This designer is responsible for medium voltage switch gear and special applications. His comment was that if the IR window is UL rated for application it will not harm their rating.
This particular manufacturer (international and well known) does install them at the request of their customers.

But, he says the problem is that the customers don't understand the problem in installing them in different models of switch gear. In their ARC safety cabinets which are designed to direct and vent the energy and debris up and out the top, the IR windows aren't useful. The metal baffles/shields within the cabinet block the line of sight. So the cabinet needs to be opened and the baffles/shields removed for a thermography scan to be effective. Now NFPA70E comes into play since all the protection has been removed. Only in the non-ARC safe cabinets can the IR windows be installed and be useful, and ARC safety is still a concern, the window only saves the labor of removing the skin. Personal protection is still an issue since the cabinet is not ARC safe rated.

There are other solutions so thermal monitoring can be performed without opening and taking apart the cabinet. This is where the permanently mounted Thermal IR monitoring systems are used.
And even with non ARC safe cabinets, such a system keeps the technician from having to get into a ARC threat zone for an inspection.

This message has been edited. Last edited by: BKern,

We have been involved with the installation of a few of the inspection windows on high voltage transformers used in underground mines here in Australia. The company that fitted them is accredited repairer for intrinsically safe equipment.

As far as cost goes, our customers would prefer to invest about $1200 than rebuild a transformer for up to 20 times this value.

Remember : Choose the right horse for the course!

Hooch

Hi Bkern,

I do not agree totally with the statement about IR Windows not being useful on Arc-Resistant equipment, I would like to know who this person worked for!!!

Without being too commercial, I can say that the Hawk product line has been testing in-position into various arc-resistant designs to both IEEE and IEC standards during relevant type-tests. As the switchgear/window combination passed the test, the IR scan can be completed via the window as it provides the same level of protection as the switchgear. Also, Arc-resistant equipment generally has chutes for cable runs which allow circuit segregation and pressure relief systems built into the upper section depending on whether they are classed as Type-1 or Type-2 arc-resistant systems this may include an exhaust plenum. Correct IR Window placement allows viewing of the most common failure points i.e. the Cable terminations even on double-stack breaker systems with cable segregation. We work with most manufacturers to ensure correct placement for the end-user.

Main bus and breaker stabs on MV VCB's are generally not accessible on either arc-resistant or non arc-resistant gear, even if the covers are removed and this is an area where constant monitoring systems can be installed but they have their own problems.

On all electrical equipment Arc-resistant or otherwise, care should be taken when working closeby. NFPA70E uses the term "Exposed Conductor" to define the initial requirement for PPE, what we need to be aware of is the non Arc-resistant equipment will probably fail should an arc-flash occur within as it was never designed to withstand the blast. This then generates the very correct question "should we even be near it? Even with the covers closed!" The answer should be NOT UNLESS YOU HAVE TO. Too many people take electrical equipment as being safe with the covers closed, bottom line; it is NEVER safe. Switchrooms should not be used as shortcuts between areas, personnel in close proximity to live equipment should be aware of the risks and correct PPE should be selected.

What is more concerning to us is the focus on MV equipment. LV equipment can have a far higher short circuit current and cycle time associated with it than the MV, this along with the regeneration effects of downstream loads usually result in extremely high incedent energy levels. If anyone doubts this, a good example is a close-coupled package substation. The MV Disconnect will probably be running at 13.8kV with a transformer dropping the nominal voltage to 480V. Performing an arc-flash hazard analysis on this lineup will more often than not show that the arc-flash boundry and danger levels at the LV section are far higher than the feeding MV switch. The corresponds to a higher PPE Requirement in accordance with NFPA70E at the LV section than the MV, but even today folks open 480V LV boards without PPE when multi-layered FRC is worn to shoot the MV Switch. Education is the key here and by the way, LV switchgear is almost exclusively non Arc-resistant!!!!

My opinion is that IR Windows/Sightglasses/Ports, properly designed, tested and installed are simply the safest method of shooting IR on energized electrical equipment. There are no dynamic elements involved in the scan as the covers remain in place, the removal of which is the most common trigger of arc-flash.

Of course this is just switchgear, there are many other applications to be considered; Transformers, MV Motor boxes, LV Panelboards etc. etc. etc.

For further information, please don't hesitate to contact me!

Best regards,



Tony Holliday
Hawk IR International Inc.
TOLL FREE: 1-877-4-HAWKIR
Email. tony.holliday@hawk-ir.com
Web. http://www.hawk-ir.com

Hi Tony,

I'm not sure we are talking apples to apples here. But after re-reading your reply again, I do see that you briefly do touch on it in your second and third paragraph. It might be a matter of specifics, terminology and designers' concerns of one version of his equipment.

Specifically, The Statement of not being useful on "Arc Safe cabinets" (not arc resistant equipment)for switch gear, came from that persons experience with the many layers of panels between different portions and bays in the switchgear cabinet.
Which it seems you do somewhat acknowledge.

Also this person never stated "Arc resistant", but discussed "ARC Safe" Cabinets. As you stated in your third paragraph, and as he described to me, there are panels,chambers, and baffles to direct the event up and out and away from a person standing next to the cabinet. And as you mention, these items do hinder the scanning of certain targets, so an IR sightglass may not be the solution for complete IR monitoring of all the targets with in this style of cabinet. After all, isn't the reason to install an IR sightglass so that the tech does not have to disassmbly the cabinet? And why do go for a solution that doesn't allow for scanning of all targets? Shouldn't another solution be sought after at such a point? If targets can't be scanned through a sightglass, should they be forgotten about?

On there other style of cabinets they do install sightglass as requested by customers.

This engineer simply stated that having sightglass on the outer skin does not allow for inline vision of all the connections and junctions that are behind other "blast" (for lack of a better word) panels and ducts. The engineer described to me many layers of panels that would need to be removed for a complete scan. So on these Arc Safe cabinets they were opting for constant IR monitoring. The next time I have a chance to speak with this engineer I will ask him the difference between his label of Arc Safe Vs Arc Resistant. At face value I understand the difference, but not being a designer of such equipment, I can not speak for his use of a particular label.

Companies that use constant IR monitoring do not stop performing thermoghraphy inspections. I see the two complimenting each other very well. Companies that use constant IR monitoring systems are more concerned with predictive maintenance and trend monitoring in their mission critical systems than most.

Hi Bkern,

It may be we are actually in agreement!! I made the assumption that Arc-Safe and Arc-Resistant are the same thing and I still stand behind it. Allow me to explain my reasons. In order to claim a piece of switchgear is Arc-Resistant it must have been subjected to an arc-flash test programme to a third party standard such as IEEE C37 or IEC62271, from a liability standpoint manufacturers cannot and will not claim something is Arc-safe or Arc-resistant unless they have passed such tests. This is probably a difference in our terminology but the end product is basically the same, i.e. a power system that will not fly apart should and arc-fault occur.

When considering IR Sightglasses - or any monitoring system for that matter - at all, one must always look at system critical points to monitor. Although main bus systems are definately system critical and generally cannot be viewed using IR Sightglasses, research shows that they are not the most common area of failure due to the fact that main bus connections are generally made in the factory under strict quality control. Problems on main bus DO occur but they are almost always associated with transit sections whose bolted are torqued on-site during commissioning, these jointing sections are few and far between. The first area to scan is always the cable connections, this is a recognised area of failure as the cables are generally made off by third party personnel who are normally paid "per termination". It only takes one of these cables to be using the wrong lug size or be incorrectly torqued and it will explode. There is only one system I have seen anywhere in the world where cables were not viewable with a sightglass and it was an IEC type, Arc-resistant design manufactured in Asia. For every other system we have been in contact with we were able to install sightglasses to view the cables.

Constant monitoring systems do have a place BUT my worry is one of integration, accuracy and operation. An infrared thermographer shooting power systems invariably looks for "hotspots" first and then inserts correct parameters into the camera to obtain a correct radiometric image that can be assessed for criticality. Online monitoring systems generally use non contact infrared thermocouples to obtain the base temperature data. These systems take an average on the base of the FOV cone and the options I have seen incorporate a spot-size of around 6:1. This means that at six inches away the minimum measurable point is 1 inch, at 12 inches away the minimum is 2 inches and so on with NO emmissivity adjustment or reflected temperature input. How can these systems ever be deemed as accurate? They may or may not even be able to "see" the target because of the spot-size ratio and yet their results are being relied upon as a method to assess system health, this is OK if they happen to see an increase in temperature BUT what about all the times that they do not? On low E target materials such as exposed copper bus it gets worse, my opinion is that these systems are simply not acceptable I would rather assume that the main bus has to be scanned using ultrasound at the joints in the panel or routinely pm'd in accordance with established MTBF timeframes for the bus than rely on these devices at this stage in their development. Undoubtably they have a place in the future of pdm for inaccesible power systems but they are too young in my opinion to be reliable in a measurement sense.

Just my thoughts!!



Tony Holliday
Hawk IR International Ltd.
TOLL FREE: 1-877-4-HAWKIR
Web. http://www.hawk-ir.com
Email. tony.holliday@hawk-ir.com

Quote" Constant monitoring systems do have a place BUT my worry is one of integration, accuracy and operation. An infrared thermographer shooting power systems invariably looks for "hotspots" first and then inserts correct parameters into the camera to obtain a correct radiometric image that can be assessed for criticality. Online monitoring systems generally use non contact infrared thermocouples to obtain the base temperature data. These systems take an average on the base of the FOV cone and the options I have seen incorporate a spot-size of around 6:1. This means that at six inches away the minimum measurable point is 1 inch, at 12 inches away the minimum is 2 inches and so on with NO emmissivity adjustment or reflected temperature input. How can these systems ever be deemed as accurate? They may or may not even be able to "see" the target because of the spot-size ratio and yet their results are being relied upon as a method to assess system health, this is OK if they happen to see an increase in temperature BUT what about all the times that they do not? On low E target materials such as exposed copper bus it gets worse, my opinion is that these systems are simply not acceptable I would rather assume that the main bus has to be scanned using ultrasound at the joints in the panel or routinely pm'd in accordance with established MTBF timeframes for the bus than rely on these devices at this stage in their development. Undoubtably they have a place in the future of pdm for inaccesible power systems but they are too young in my opinion to be reliable in a measurement sense." end quote.

I agree with Tony that the constant monitoring he describes will not provide accurate temperature measurement. However, in my opinion neither do infrared windows. If I am imaging through an infrared window I would not in any way rely on the accuracy of the temperature measurement.

Hi Gents, I hope all are doing well.

Actually the accuracy is very good.
There are many more options for the FOV, ranging from 1:1 up to 10:1. The correct sensor is selected based in distance and the size of the target. The better IR sensors measure delta T, not absolute temps.

For items such as smaller wires and such, cable contact sensors would be recommended. Such sensors are mounted on the insulating jacket of the wire. Yes, you won't measure the exact temperature, but for the purpose of finding detecting pending failures, one is looking for a abnormal change in the temperature of that point. Remember these systems are tracking the temps all day long, everyday of the year. So trends can be spotted and alarms are incorporated.

If one has a 3" bus bar, the bolted connections are what would be monitored. If there is several 500MCM lugged wires bolted to the bus bar, as long as ~60% of that field of connections are within the FOV, the connection will be monitored and faults seen.

The biggest problem with the selection of a sensor, is if the FOV is larger, looks over the target. Then accuracy becomes a problem.

The thermal monitoring system engineer and installer are trained to perform the proper selection of sensors.
Just as for thermography to be useful and meaningful, the technician must be well trained with issues pertaining to targets and with the IR equipment. The compensations the technician must make can make or break the scans.

To determine a failure, and to see if the PM cycle is too short or can be lengthen, measurements to 1 or 2 degrees aren't required.
If a connection of lug was to come loose on the bus bar, it will contribute much more than a 5 deg rise to the temp rise above ambient of the target.

The bus bars and such are excellent conductors of heat. Of course if there is another batch of bolted connections a foot away, another sensor must be used. The heat radiated and conducted by a failed joint does wonders for heating up and the physical connection.

As with any infrared measurements, the emmissivity and reflectiveness of the target is an issue for any IR measurement. The accepted practice for full time monitoring is to paint the target, just a bit more than the FOV of the sensor. No adjustments need to be made. No compensations to be made “during” a scan, hence no operator errors and no guessing.

Such systems have been in use and closely watch in the UK for 3-5years now, with new installations happening every year. Owners of very large critical data systems, infrastructure system, and one cruise line have adopted the system with great success. There are two major switchgear manufacturers that are just now starting to offer these systems installed during manufacturing of their equipment. Other engineering firms are starting to offer the system for monitoring of critical components when designing a critical facility.

After two years of testing, one system was approved for use in the "chunnel" and will be deployed.

One never knows if more or other points should be monitored. So a permanent system is a compliment to periodic scanning to help save labor and to save injury.

Hey guys, interesting discussion here. The first manufacturer of Arc-Resistant switchgear in the US designed to ANSI standards was Powell Electric in Houston, TX. Second to the game was ABB out of Sanford, FL. I hear GE has a product now as well. AR gear is still a very small percentage of total switchgear shipped in the US, mainly because the end users are somehow still unaware of arc-flash dangers and don't want to pay the added cost for AR gear. I know the Powell AR gear does NOT have panels that block the view of the cable connections to the runback busses. ABB gear DOES. Not sure about GE's product as I have not run across it yet.

I have seen IR images taken through IR windows that show a beautiful delta T on runback bus and accurate temp measurements because the transmissivity of the window is calibrated in the camera or field calibrated. The runback buswork the cables connect to in the termination section of switchgear is a direct indicator of problems upstream. One thermographer at a utility found a hot runback bus in the cable termination compartment in old ITE gear and the problem was a loose breaker finger stab assembly on the primary side of the breaker.

I do not have experience with these IR thermocouple monitoring systems. How much would it cost to retrofit a lineup of 15kv one-high gear with 12 sections? Are the thermocouples fail safe (for eg. what do you do if one fails and the next outage is in a year? Since they must be mounted inside the enclosures do they reduce dielectric clearances? What do they communicate the information to? Is is a relay with readouts on the display or does it require a PC type device to do realtime monitoring?

Thanks for the info.

Hi Troy,

The 24/7 Thermal Monitoring system I am involved in is all I can speak to.

Yes the IR sensors were designed with a fail-safe mod. If a sensor were to fail, the reported reading goes to 2,000 degs, sounding the alarm.

The calculated MTBF of the IR sensor is 1,000 Years (not hours). Over the last 5 years many thousands (about 2,200 in on installation alone) have been installed in the UK with no failures. I don’t have an exact number, but I’m estimating about 5,000 – 6,000 have been installed to date. Each year new installations and retro fits are won and performed.

The system went through 2 years of extensive testing.
And was approved and selected for use in the Chunnel.
It was selected because:
The high demonstrated & calculated MTBF of the sensor and system components.
It’s tolerance for noise and lack of false alarms during the 2 years of testing.
It’s accuracy for detecting the pending fires it was tested against.
The solution for the Chunnel will use the IR sensors in arrays to detect heat sources to avoid any fires such has happened in the past that almost destroyed the Chunnel.

The IR sensors are passive. They contain no electronics. They do not require any bias. They require no calibration.

The Sensors report to a data card that is outside the switchgear. If a data card was to fail, it is easy to replace. To date there has not been one failure of a data card either. Again, if the data card was to fail, the software reports all if its channels (8 on each) as 2,000 degs.

The data card reports to the systems own data loop, which has a watchdog system in place. If the data cable were to open or the card to fail, the alarm would be sounded as well. The data loop reports to a communication box, which is connected to a PC with the system software. If the software cannot talk to the data loop, it will make every channel on every data card 2,000 degs. The software writes a log of the temperatures measured during the day to a text file. Each day a new text file is started. The software has graphing software built in so trends can be plotted and quantified by the engineer.
The text file can be imported to excel or other spread sheet programs as well.
That communication box can be changed to talk directly to Modbus, Profibus, and such. To date, the engineers have designed and tested communication solutions for over 400BMS systems and protocols.

The “alarms” are part of the Alarm card (which is also part of the watch dog function). When an alarm set point is exceeded (there are two per channel), the dry contact relays on the alarm card change state.
So anything can be done with the SCADA compatible dry contacts. Also a bit is changed on the PC, locally the PC sounds an alarm. Optionally, our software engineers can work with the customer to integrated the software into the BMS system.

The software has two basic screens. One screen looks like two large/dense Bingo cards. Each square represents a channel, each row a data card. If a channel changes from green to yellow or red it’s very noticeable. This way when the alarm is sounded, one can quickly find out what sensor on what data card is reporting a problem. The other screen is the detail information for that data card. Switching to that screen, one is able to bring up the data card with the alarm, read the descriptive information of where and what that sensor is about. I can email you links to screen snap shots if you would like.

More and more, the end customer has chosen to integrate the system into their BMS SCADA system and do away with the stand alone PC. So the data from the system is polled by the BMS system and displayed on their particular SCADA layout.

This year a data card has just been released that doesn’t need the software and doesn’t need the communication loop. The new data card talks directly to Modbus and 4 other common BMS busses.
That new data card not only accommodates a mix of temperature sensors as the original data card does, but can also be programmed to measure voltage, current or accept a 4-20ma loop.

I’m not 100% sure if I’m able to provide ROM pricing openly on the forum.
Your welcome to email me, (bkern@psc-exertherm.com).
If a moderator chimes in and says it’s ok, I’d be more than happy to share some averages for $US per point.
For detail pricing, we would have to talk in more detail to outline equipment requirements. But I can provide ROM pricing off the bat. Some smaller systems have used all IR sensors, so the average price per point is higher. Larger systems have used a mix of cable contact sensors and IR sensors, dropping the average equipment price. So based on that I have some averages I can share with you.

Eaton Cutler Hammer, as I understand it has the same concerns as ABB.
As well as manufacturers of Bus Duct systems.

All the mounting hardware is hi temp UL rated Nylon, the sensors can be mounted to comply with spacing requirements. Being all UL material, and non-conductive, there are no inherent problems. The sensors, materials, and mounting system have been accepted in the UK. But for NYC approval/application, we are going for local testing and approvals. The Sensors and mounting systems are in UL now for recognition.

Sensors are selected based on the width of the bus to be monitored, the distance the sensor will be away from the point to be monitored, and a 70% coverage goal for the FOV (field of view).

The basic selection of IR sensor FOVs are 1:1, 3:1, 7:1, 10:1.
So at 1 inch, there is a 1 inch FOV, at 3 inches of distance there is a 1 inch FOV, and so on.
If 3 inches of clearance is needed, or that’s where the mounting point is that’s available, and the bus is 4” wide, a 1:1 would be used. We would then have a 3 inch field of view (70% coverage is the goal as to have some margin of error for aiming so the background is not in the FOV). If the mounting point needs to be further away, a 3:1 or 7:1 can be selected. Rarely is a 10:1 needed.

If it’s a cable feeding say a small PDU, commonly a cable sensor, a contact thermal couple is used, not and IR sensor.

We do not see the system as something that will be replacing Thermography, but rather complimenting it. We see the system as another tool, an advance in capabilities for Thermography professional and the Engineers that need to monitor critical items and hard to access points. These professionals now have another solution / service as well as trend analysis to offer their customer that compliments the Thermography.

We have one very large manufacturer using a well regarded Thermography Engineering Service.
Every month they were scanning the PDUs for the very high surge energy production equipment. At week 3.5 one panel practically blew off the wall and damaged some production equipment and product. Thankfully no one was hurt. Apparently something was marginal or missed 3.5 weeks ago, or developed in the last 2 weeks. One of the many lines shutting down was a very expensive loss of capacity for them. Things happen, that’s why we all buy all sorts of insurance policies. But wouldn’t we rather prevent losses? If it’s that important, additional monitoring should be considered.

Sorry that this reply became rather lengthy.
But you had good questions and I wanted to answer them as thoroughly as possible.

I hope this helps.

Bob Kern
Bkern@psc-exertherm.com