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Key Points to Consider when Preparing to Test Military and Defense Equipment

Element delivers an extensive range of testing and validation services required by defense manufacturers during qualification to help meet the rigorous demands of military standards. These include Def standard 59-411 and Mil standard 461, as well as more specific aerospace standards such as RTCA DO-160 for indirect and direct lightning testing. 

Defense products and components must undergo the most stringent testing available to ensure that they can be relied upon in even the harshest of environments. Element’s EMC and environmental chambers enable almost any setting to be replicated to subject equipment to extreme conditions including heat, cold, dust, and electrical interference.

To ensure testing runs as smoothly as possible, Element’s defense experts have put together a summary of key points manufacturers should consider when preparing to test products or components for the defense market:

 

1. Have the constraints of the penetration panel been taken into account? 

Providing the grounding/shielding and filtering between the EMC test environment and the outside world, the penetration panel is a vital consideration when preparing to test. 

This should include, for example, the position and the measurements of the penetration panel to ensure all the necessary cabling and wiring will fit through it easily. This will prevent any delays regarding the linking of the test product to the external support equipment. If any cables are an unusual size, it may be worth considering bringing your own penetration panel.

A common mistake is to bring plastic connectors which, as they are ungrounded, can’t be used to connect to the metal connectors on the penetration panel. 

Element can provide measurements in advance for all of its testing chambers and the penetration panels, including diagrams for their precise useable areas as they are not all identical. For example, the EMC Chamber Penetration Panel is 400mm x 400mm x 2mm Aluminium, while the Reverberation Chamber Penetration Panel is 315mm x 315mm x 2mm Aluminium. 

Available diagrams incorporate all the EMC chamber dimensions, including penetration panels and a choice of bench dimensions.

 

2. What support equipment is required? 

When planning to test, it is essential to consider what support equipment will be required. This could be anything needed to operate the EUT, mount the EUT, or provide the ability to function the equipment under test (EUT) remotely if necessary. 

Loads, supplies, and signals are all key considerations. If the test subject requires a load for testing, it is important to ensure the dummy loads are suitably set up for the system and are prepared and ready for when the testing date is confirmed. 

Finally, one of the critical pieces of equipment that we frequently see causing delays when preparing to test is the cabling and connectors. It is vital to plan what cabling will be required and ensure the cables are the appropriate lengths. It is not uncommon for the cables to be too short to run along the front of the test bench and reach a breakout panel without stressing any of the cables themselves or the connectors. As a general rule, too long is always better than too short.

 

3. Have you considered the appropriate power supply and connections?

The power supply and power connections can both be evaluated before test day to avoid any power-related issues or delays.

Regarding the power connection, providing the power lead is the correct length from the EUT, then a 6mm ring terminal will be the safest option to connect to the filters/ LISNs in the testing chamber. If not, bare wires should be left for trimming to the correct length. The power line length is defined in the test specification.

Element can provide a number of power supplies solutions including, for example, up to 28 VDC, 115 V 400 Hz AC and mains supplies.

For the power supply, it is important to inform Element about the current draw of the EUT, including inrush, to ensure the correct power supply is ready and available.

In addition, if there is a specific bonding strap required for the product, it is vital that it be brought to the testing laboratories, although alternatives can be provided on the day if required.

For some tests, Element will need to monitor individual power lines next to the EUT. If this is the case, advance notice of whether the power cable is screened/armored should be given.

 

4. Are the Dwell Times clearly established?

Dwell times, the time spent at each frequency to measure emissions or check for susceptibility, are frequently a cause of delay when testing is about to commence. 

Dwell times can vary greatly with each specification, and it is vital to understand what the impact of this might be. This means considering how long your equipment takes to do one complete cycle of functions to enable all potential emissions to be captured or how long it will take to check the whole operating cycle for susceptibility at each frequency. 

When testing to a lot of frequencies, it is important to be aware that the longer the dwell time for each frequency, the longer the overall test. Failure to take the different frequencies into account can lead to testing overrunning and, on a practical level, may mean the chamber has not been booked for long enough, which could delay testing being completed. 

 

5. How will the test be monitored? 

Deciding how the test is going to be monitored is often left until the last minute and can cause unexpected delays in testing commencing. Therefore, it is essential to understand what monitoring equipment will be required and if the equipment will enable the EUT to be checked for correct operation remotely. 

If video cameras are going to be used, planning their positioning and exact angling to ensure suitable viewing should have already been carried out. 

If the electronics are going to be monitored using laptop software, it will be necessary to check in advance that all the appropriate displays or devices required to ensure the monitoring is comprehensive and runs smoothly are ready and available. 

When carrying out monitoring of the EUT, some tests can be exceptionally long and might need to be repeated many times with slightly different parameters. If this is the case, it is worth considering if the EUT can be monitored with software that automatically latches when a failure is detected.

 

Conclusion

While advanced planning can make a huge difference to how smoothly a test program runs, the reality is that many products will fail the testing the first time around. Building in contingency time to your project timescales is therefore strongly recommended. The goal of testing should always be to pass the first time, much can be learnt from failed test cycles, and the key is to ensure that any additional time required is kept to a minimum.  

Thinking about product compliance and qualification from day one and involving testing experts on projects to give support, advice, and technical expertise can reduce the chances of failure and speed up the testing process.

To learn more about testing of products to the required military and aerospace standards, please contact Element’s specialist military and aerospace team by emailing contact.us@element.com or request

 

Military and Defense Testing Standards

Element routinely tests to the following common standards:

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