...As you know, certain 28V automotive bus systems are saidd to suffer surges of "100V for 50ms". MIL STD 1275E tells that equipment connected to the 28V bus must keep delivering max load power throughout this surge. (ie, not just simply switch the surge out from its inputs)
Page 3 of this below, tells what causes the surge voltage of "100V for 50ms" on the 28V bus of certain automotive systems...
ti.com surge protector App Note:
..it says that these such surges "
occur during motor events, such as the main turret turning, which is then seen by any accessory that is connected to the 28-V bus."
...Do you agree that this just doesnt sound right? Admittedly the current drawn from the 28V bus to turn the turret would be high. ..Then when the turret stopped turning, the energy in the stray inductance of the 28V bus would need somewhere to go....but surely it would simply go into the input capacitor bank of the turret motor, and thence not cause any overvoltage at all?....
...If the input capacitor bank gets dried out (eg with age, wear-out, etc), and becomes less in capacitance, then the stray L energy would still need somewhere to go, and so would surely charge up that input capacitor bank to more than 100V....in which case , any item on the 28V bus, that was in accordance with MIL STD 1275E, (ie, protected up to 100V surge) would fail anyway?
As such, would it not be better to simply switch out the surge, rather than try and port the device running current through an enormous, step-down, linear regulator, during the surge? Switching out the surge would result in non-service of the load for approx 100ms or so, but at least it could resume operation after that......i mean, you could always make the device go into "power throughput limited operation" mode during the surge aswell, so that if it happened to be on light load at the time of the surge, then the Vout woudlnt drop out at all anyway.
And in any case, many devices have an input battery which would see them through a 100ms surge anyway.
Isnt this standard ill thought out?
..Also, its wrong to call it a "voltage surge"...since it is a surge caused by current flow in the stray inductance..when the turret stops turning, the voltage on the bus will rise to whatever voltage it rises to, in order to keep the broken stray inductive current flowing.
Also, since the turret motor current is known, and so too is the stray inductance of the 28V Bus...then why not just put a proper surge arrestor on the 28V bus, to handle that?.....So, why put "ride through" surge protection in every single device? In any case, if all the devices on the 28V bus are on light load when the surge happens, then without a surge arrestor, the bus voltage will rise to well over 100V anyway.....making MIL STD 1275E a waste of time.
So surely you agree, that what is needed, is a proper surge protector on the 28V bus.....and nothing more than simple "switch-out" surge protection in every device on the bus?
Please do not fear giving away military secrets by responding to this, virutally the entire Western Power Electronics and SMPS sector has already been outsourced to outside of the West anyway.....leaving the West massively way behind in this respect, so you'll only be telling things that those outside the West already know far batter than the West anyway.