Power in, power out, prevent accident.

Thread Starter

draw2build

Joined Nov 25, 2022
12
I’m connecting two power sources to one output, One is a positive output and the other is a negative output. It works when one is on at a time.
I’m trying to protect it so that both power sources don't accidentally get turned on at the same time.

So, I’ve added a high/low trigger relay module. I got the first relay to work just fine. I’ve connected the DC+ to IN1 because when the power source gets turned on the relay turns on.

By connecting the second power source, in the same way, continuity makes both IN1 and IN2 triggers, and both relays turn on.

If I'm using the right type of module what can I do about the wiring? Or, is there another type of module I can research?
FYI- I've attached a pic of my connections.

Hook-Up.jpg
 

Dodgydave

Joined Jun 22, 2012
11,318
Just use IN1 and IN2 on their own and it will work. You need to wire the relay contacts across the supply and use the Com terminals to feed the load.
 

DickCappels

Joined Aug 21, 2008
10,226
I would use a simple approach: Single pole, double throw switch. That way only one power supply can be connected at a time and they are (supposedly) never connected to each other.
 

Thread Starter

draw2build

Joined Nov 25, 2022
12
Just use IN1 and IN2 on their own and it will work.
This is what I would like.
You need to wire the relay contacts across the supply and use the Com terminals to feed the load.
I'm so sorry, but I'm not getting it. Can you please tell me what to what? I've written out what I tried, on the left side. No Power.
(Left Side)
Power + to IN1
IN1 to NO1
Power - to DC -
DC - to NC1
Com 1 to Device +
NC1 to Device -
 

KeithWalker

Joined Jul 10, 2017
3,137
To automate it, you need to prioritize which supply should be connected if they are both present. Once you have done that, it is simple relay logic.
 

AnalogKid

Joined Aug 1, 2013
11,128
I’m connecting two power sources to one output, One is a positive output and the other is a negative output.
Please explain this in more detail. Manufacturer / part numbers would help. Post #3 assumes that the common or return or GND connections of the two supplies can be connected together, and a SPDT switch selects which + output goes to the load. My read of your post is that the two supplies cannot be common-grounded, so you need the equivalent of a DPDT relay. This can be two SPDT relays if connected correctly.

Here's the question:

If both supplies (we'll call then PS1 and PS2) are active at the same time, which one powers the load?

ak
 
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