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Thread: Correct circuit breaker for small single phase pump motors

  1. #31
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    Something i learnt when designing and building control systems for water treatment plants... less is better... the operators on site generally just want to see a green light to say thumbs up... and a red to say it is bad and they might tell someone to call the "technician" ...i have seen people rip the a$$ out of projects to make a ton of cash and all it does is confuse the crap out of the operator.
    Comments are based on opinion...not always facts....that's why people use an alias.

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    Thanks @Ians, wise words and I fully agree with you. KISS is king when it comes to operators, especially a housewife!

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    Someone mentioned or posted something about 48 volts max for float level control... i am busy installing a low level cut out switch and i see the float level is rated to switch at 250 volts.
    Last edited by ians; 21-Nov-19 at 09:10 AM.
    Comments are based on opinion...not always facts....that's why people use an alias.

  4. #34
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    Quote Originally Posted by ians View Post
    Someone mentioned or posted something about 48 volts max for float level control... i am busy installing a low level cut out switch and i see the float level is rated to switch at 250 volts.
    As far as I know the intention for these float levels are to switch low power pumps. Having said that I always design these on a 230V system to switch the neutral of the 220VAC relay. I have seen installations where the float level switch is wired on the live, actively switching the pump under water with 2230VAC. I will look into the 48V as I remember the same.

  5. #35
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    I have had a look at the Subtronic DIN rail pump controller as Victor sent me to test. It looks good, smells good and should taste, oops, work good.

    So my only issue is that to control six pumps I need six controllers and this will not all fit onto the same panel. I therefore want to convert the storage cabinet next to the electrical cabinet in the skid into an electrical cabinet to accommodate the additional controllers and the C/B of each. The two panels will each be in its own housing but fitted tightly against each other in the same skid. There is already a lockout isolator installed for the skid.



    My first question: Do I need to install an isolator for the second cabinet or can I feed directly from the L+N distribution blocks in the first cabinet?

    Basically:- cable --> Isolator --> E/L on first panel ---> L distribution block and N distribution block ---> C/B for each pump and electrical equipment.

    My second question: The skid is supplied with 230VAC as follows: DB ---> E/L ---> C/B ---> cable ---> skid isolator. So do I need another cascaded E/L in the skid or is the one in the feeding DB enough?

  6. #36
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    Quote Originally Posted by mygoggie View Post
    My second question: The skid is supplied with 230VAC as follows: DB ---> E/L ---> C/B ---> cable ---> skid isolator. So do I need another cascaded E/L in the skid or is the one in the feeding DB enough?
    I found my answer here - https://www.theforumsa.co.za/forums/...l=1#post141115

    So I will change the supply in the main DB to be before the E/L there and install an E/L unit in the skid.

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