Hello all,
I want to know the effect of connecting grounds in switching power supply with different loads and different voltage.
In one of my design I am faced with a strange problem. Here as you can see I want to drive a 24V-5A motor. But as I switched the circuit on (my transistor is something else, A BDX53) my house fuse blew. whats wrong with it?

 

Hello all,
I want to know the effect of connecting grounds in switching power supply with different loads and different voltage.
In one of my design I am faced with a strange problem. Here as you can see I want to drive a 24V-5A motor. But as I switched the circuit on (my transistor is something else, A BDX53) my house fuse blew. whats wrong with it?

Hi..Welcome to AAC

unfortunately for you, first person to "answer" your question is a neophyte

There's resistor from the micro-controller to base of transistor to limit current?

"my house fuse blew" lol, really funny..

 

Was if a fuse/breaker, or a RCD?
What exactly are the power supplies?

 

Hello all,
Thank you for your reply.
Yes, I have limited my transistor. it works fine with a linear (transformer) 24V adapter.
In home, we have only fuse/breaker no RCDs.
My power supplies are two different switching mode power supplies(24V/10A, 5V/2A).

Is there any problem to connect ground of two power supplies? because I have heard that I should prevent connecting SMPS ground to each other when have more current( I don't know why)

 

You can check the continuity between PE and the output, but my guess is they should be isolated. Not really sure why if would blow the fuse in any case.

 

Thanks for your comment. still I am confused by this circuit behavior.

 

You have used the Earth GND symbol for common, is this actually earthed or have you just used the wrong symbol for power common(s)?
Personally I would use a logic gate Mosfet to drive the motor.
Max.

 

Thank you MaxHeadtoom for your comment. Yes, I have made a mistake for drawing the ground in the schematic. But in reality, I have connected my GND to -VIN of my adapter.

 

The power supplies may need minimum loads to function properly.
Sense leads, if required, not connected.
High inrush current.
Could it be an RCD trip?