Timeline for Current surge protection for relay contacts when closing
Current License: CC BY-SA 4.0
5 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jul 26, 2021 at 1:30 | comment | added | D.A.S. | Yes that’s why PC PSU’s disable startup for at least 1/2s after shutdown or disconnect with other timers so that intermittent connection with switch on doesn’t surge those using ICL’s for main power | |
| Jul 26, 2021 at 0:32 | comment | added | Jerther | I understand. There's one thing that occured to me though. Let's say the capacitors have just been charged and the 2nd relay just kicked in so the NTC is still hot, and then the battery is immediately disconnected and the capacitors discharge faster than the NTC cools down (and I believe they actually do). If the battery returns immediately after that, the NTC resistance is going to be low so there's going to be a surge. This could happen for instance when connecting the battery. Am I right? | |
| Jul 25, 2021 at 16:40 | comment | added | D.A.S. | You chose the time delay. Yes it significant as the ?Ax4 Ohm drop means the caps don’t charge up to desired >80% and the 2nd shunt relay will get the surge next. The ICT saves the 1st relay or FET and the 2nd can bypass both to save FET or relay losses and NTC ICT extended high temp. So you get soft start, low R and low loss with 2 relays. | |
| Jul 25, 2021 at 14:32 | comment | added | Jerther | I read NTCs tend to fail short, and have a somewhat short lifespan. Since you're talking about a 2nd relay to shunt the voltage drop, is there a significant advantage for the NTC over, let's say, a simple 4 ohms power resistor in this situation? I guess it'd be more efficient but is it really worth it for T = RC = 5*(2000 * 10^-6) = 10ms? | |
| Jul 25, 2021 at 4:00 | history | answered | D.A.S. | CC BY-SA 4.0 |