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Starter question!

apostrophe

Hi

 

This is probably a bit of a noddy question, but hopefully this is the best place to ask it!

 

I am building a small control system based on a Raspberry Pi with a PiFace digital board and two additional 12V relays for switching some solenoids.  I have one 12V source coming in to the system and wish to have that source supply all of the devices.  There is a 12V to 5V step down for powering the Pi.  I was told to simply connect the 12V supply in to a couple of feed through terminal blocks and supply the components from those blocks, sounds simple enough.  The issue is there are vast number of terminal blocks available and I do not know what specifications to be looking at to select the correct blocks!

 

So the questions are:

1. Are feed through terminal blocks the correct solution and if so how do I choose the correct blocks?

2. If feed through terminal blocks are not the correct solution what is?

 

Thanks

  • 0

    Hi David,

     

    There are many options to splitting the supply and connecting to the relays, but without knowing much else about the connections on the relays (i.e. are they solderable, or spade type connections) then probably you can solder and use heat-shrink on them, For the splitting of the supply, again heat-shrink is usually fine for insulating the connections after they have been soldered. Otherwise, there are various crimp or terminal block options. One possibility if you don't want to solder, is to use terminals from Wago, e.g. any of these:

    wago terminal Standard Terminal Blocks | Farnell UK

    If the other side of the relay is switching mains solenoids, then electrical safety standards need to be adhered to, and then all sorts of things matter - what enclosure, how the mains entry is achieved, what relays, etc. Otherwise, if things are at 12V and (say) under 5-10A then you're fine with virtually any connector (the datasheets will specify what the maximum ratings are for the connectors).

  • 0 in reply to shabaz

    Hi Shabaz

     

    The solenoids I will be switching are all 12V, I am planning to user relays with screw connectors to make connections easier to avoid soldering etc.  Thanks for the details on the terminal blocks, my issue is I don't know how to determine what is the maximum voltage and current that will be passing through the blocks.  Is it from the source or the load, do I multiply the 12V by the number of devices I have?  Do I add all the current values together?

     

    Thanks

  • 0 in reply to apostrophe

    Hi David,

     

    You can just add the current consumption of each 12V device, if they will be powered up together. Add about 1 amp for the raspberry pi.

     

    That will give you the total current consumption that your connectors must support at a minimum. You don't need to add the voltages. Any connector will be fine at 12V.