• • • SURGE & CIRCUIT PROTECTION • • •
The Rheinmetall Lynx Infantry Fighting Vehicle (IFV) uses advanced circuit protection components to meet stringent industry standards
How to survive load dumps on active
protection systems in military vehicles By Ian Doyle, Director of Sales & Marketing EMEA, ProTek Devices
A
rmoured vehicles are methods of heavily protected transportation, designed to shield soldiers and weaponry from enemy fire. The
equipment is costly, but their failure can mean a loss of money and life. As a result, countries spend a serious amount on defence. According to recent reports, the US spent $997 billion last year, Germany nearly $89 billion and the UK nearly $82 billion. Helpful in this spend is adequate protection for vehicle subsystems that are vulnerable to common electrical transients. These vehicles and systems include armoured personnel carriers (APC), infantry fighting vehicles (IFV), remote weapon systems and more. Active protection systems (APS), which combine sensors, radar, weapons and countermeasures are increasingly being used on main battle tanks (MBTs) and are expected to expand to other types of military vehicles.
38 ELECTRICAL ENGINEERING • MAY 2025
A common load dump scenario threating military
vehicles and systems Most military electronic systems in use have common 28 VDC voltage characteristics at the input power terminal of equipment; it is directly connected to the power distribution network. For its design engineer, the most common occurrence of a positive voltage surge is an ‘alternator load dump.’
A load dump occurs when the alternator is working to charge a partially or fully discharged/flat set of batteries, and the connection to the battery positive terminal is suddenly disconnected. The alternator cannot immediately decrease its output to compensate for the sudden loss of load. Resultantly, excess surge energy delivered during this settling period is
distributed to the military vehicles’ electrical system. With this inrush of transient surge current, active protection electronic systems can be damaged or destroyed.
Overview of military vehicle
circuit protection standards Some military vehicles must comply with the MIL-STD-1275 F standard for load dump circuit protection. In table one, we see the applied transient can be as high as 110 V and may take up to 505 ms to decay. Considering that series resistance is 500 mOhms, the surge pulse described will require a max energy of about 1.05 kJoules for the longer 500 ms pulse duration.
electricalengineeringmagazine.co.uk
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56
