• • • SURGE & CIRCUIT PROTECTION • • • Table 1: MIL-STD-1275 (Rev F) load dump pulse test conditions for 28 Vdc system Table 2: DEF STAN 61-005 Part06, Issue 7 generator plus battery (fault free) condition
The average power for the quasi-periodic power function for the five pulses every five seconds is about 210W, equal to 5.1 kJoules for the total 25 second pulse train. The repetitive test of five pulses with five second intervals requires any load dump protection solution to sustain the high energy that is dissipated through the chassis or PCB. There are also military electrical systems in land vehicles that must comply with DEF STAN 61-005 Part06, Issue 7 (2020). Design engineers should note that any circuit protection devices necessary
for the equipment under test to meet the limits shall be included with the equipment under test.
Any protection solution will have to meet the clamping limit in Fig A.15 (25-30V for 1ms) and Annex C +40V, +5/-0 per cent. This includes lasting for 50ms pulse, which exhibits a surge pulse of 1,700 Joules of energy per pulse or 8,500 Joules for string of pulses. For military vehicles with load dump protection that must comply with the VG 96916-5 (2023) standard, it is like the commercial ISO16750-2 automotive standard. This includes minimum source resistance, maximum number of pulses and maximum duration between pulses. System designers must ensure their circuit protection designs are fully compliant with new load dump circuit protection standards for military vehicles. Solutions must also offer extended operating life performance while improving manufacturing cost and design time for engineers. A designer should understand that standardised surge simulations are there because they occur in real life. By implementing these robust protection mechanisms, designers can enhance the resilience and reliability of vehicle power systems and active protection systems in demanding operational environments.
Table 3: VG 96916-5 (2023) load dump pulse test conditions for 24 Vdc system
The General Dynamics Land Systems’ Abrams Main Battle Tank (MBT) is another military vehicle that is using advanced circuit protection components to meet standards such as, MIL-STD-1275 F
electricalengineeringmagazine.co.uk ELECTRICAL ENGINEERING • MAY 2025 39
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