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dc to dc converter sparks when inserting fuse

Build-A-Burger

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I have a RE system which is 48vdc from the batteries/charge controller. I have a 48v to 5v/3.3v converter, a 48v to 24v converter and a 24v to 12v converter. I'm using the fuses to turn them on and there is a noticeable spark when I insert the fuse. Can I use a relay after the fuse to turn on and off the power coming from the converters without causing too much wear on the relays?
 

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d123

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Hi,

You should be able to get an idea from relay datasheets about continuous current, instantaneous peak current, number of operations (expected lifetime), coil holding current (if lower mA is preferred/important) and decide from there or get a second opinion.

Also, depends on what fuses are protecting with regard to putting relay or switch before or after them.
 

showtown

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I have a RE system which is 48vdc from the batteries/charge controller. I have a 48v to 5v/3.3v converter, a 48v to 24v converter and a 24v to 12v converter. I'm using the fuses to turn them on and there is a noticeable spark when I insert the fuse. Can I use a relay after the fuse to turn on and off the power coming from the converters without causing too much wear on the relays?
Hi. Fuses are not designed to be switches. When you switch something like a power supply or inverter on, there is a curent surge, which is the spark you are observing. this is often caused by capacitance & inductance in circuit. (Both inverter and equipment being powered). Running curent is is less which is why these types of circuit use surge fuses. (They soak up the initial surge but then will blow if subjected to constant over curent).Fit a suitably rated switch, or relay if you want to control on off via a lower rated switch
 

betwixt

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Or you could switch using bipolar transistors or even better with MOSFETs but it depends on the topology of your wiring. You should still use fuses for protection but as you are switching fairly low voltage DC, a solid-state approach should work. The advantages are no sparks, high surge rating and the actual switches or software that turns the power off and on can be very small. Think in terms of tiny push switches or a keypad rather than big clunky fuses!

Brian.
 

Rahul_d

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I have a RE system which is 48vdc from the batteries/charge controller. I have a 48v to 5v/3.3v converter, a 48v to 24v converter and a 24v to 12v converter. I'm using the fuses to turn them on and there is a noticeable spark when I insert the fuse. Can I use a relay after the fuse to turn on and off the power coming from the converters without causing too much wear on the relays?
you can use DC rated breakers (breaker switches) with enough I2T rating followed by fuse for fault protection.
 

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