Cap Bank detector

[coconutalley]

Looking for an inexpensive, simple, effective circuit to detect when a capacitor in capacitor bank shorts out or blows a fuse and is disconnected?
Challenges:
Frequency is variable and duty cycle is variable.
Ripple voltage is also variable. The capacitors are huge
measured in Farads.

 

[VEBill]

Blown fuses can be detected using an LED (including series resistor) in parallel with the fuse. When the fuse is open, the LED lights up.

I recall someone had recently integrated the LED indicator into some automobile (assumed 12 volts) fuses.

If there isn't a fuse, then just follow the smoke.

Electric car project?

 

[ScottyUK]

Some of the larger LV fuses have a striker pin fitted which can operate a microswitch. The idea stems from the comparable system used on large HV fuses as a means of indicating fuse blowing by ejecting a pin fromn the fuse body to activate an auxiliary mechanism. Some of the Ferraz-Shawmut semiconductor range have this option - look for the square body Protistor range in the following link for an example.

http://www.ferraz-shawmut.com/advisor/pdf/SCDC.pdf

----------------------------------

Experience is what allows us make a completely new mistake every day!

 

[coconutalley]

Thanks VE1BLL & ScottyUK!
I have thought about the LED but using an opto to send the
signal to a micro, but perhaps a visual indicator is
a good thing too. The ejector pin idea is also something to consider.
The app is not automotive but it is low voltage.

 

[fsmyth]

What's wrong with a lamp? Has been used for years as a
blown fuse indicator.
<als>

 

[OperaHouse]

If you use a LED be sure to have a resistor for a discharge path across the capacitor. Decide the current for the LED (about 5ma) and calculate the resistance based on the expected voltage. Put half of that resistor valur on the cap and the rest on the LED. Put an opto and LED in series for local and remote monitoring.

 

[coconutalley]

fsymth,
Nothing wrong with lamps--LEDs have longer life [million hours]. Incandescent lamps burn out after a couple 1,000 hours.
In addition, the system needs to know if the cap bank is faulty and needs to be serviced. One way is to see if the fuse in series with cap is blown open or if the cap is shorted but has not blown the fuse.
OperaHouse,
The cap bank will have its own discharge circuit to comply
with safety. Though for voltages under 30V, it is not the voltage, it is the joules that matters.
Thanks for your comments.