Aquarium electrics

graymo · Posted: Tue Sep 18, 2007 6:44 pm Post Subject: Aquarium electrics

Hi, Im looking for some kind of switch for my water pump, that when there is a power cut or somthing like that, and the power goes back on, i want the pump remain off, i wish to switch it back on manualy if i can ? Does such a switch exsist ? thnx

TicklyT · Posted: Tue Sep 18, 2007 7:52 pm Post Subject:

Sounds like a contactor with a no volt release, as used for motor starters. They are often used on machine tools etc. where you don't want them to re-start unexpectedly.

It's basically a relay, with the coil energised through it's own contacts, and a couple of push button to operate it initially.
If the power fails the relay releases and switches the circuit off. It can only be turned back on by operating the push button.

Here's one:- http://www.tlc-direct.co.uk/Main_Index/Distribution_and_Switchgear_Index/DOL_Starters/index.html

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dannyboi2003 · Posted: Tue Sep 18, 2007 8:16 pm Post Subject:

Or you could just buy a PowerBreaker RCD plug (see pic below), when the power to them fails you have to manually re-set them to get the power back on. Much easier as you only need to change the plug then, assuming your pump is currently fed from a plug of course.

Steve · Posted: Tue Sep 18, 2007 8:33 pm Post Subject:

dannyboi2003 wrote:

Or you could just buy a PowerBreaker RCD plug (see pic below), when the power to them fails you have to manually re-set them to get the power back on. Much easier as you only need to change the plug then, assuming your pump is currently fed from a plug of course.

Is this 100% guarranteed that it wont re-energise after a powercut??? I thought it was normally a game of chance with these RCD plugs.

electronicsuk · Posted: Tue Sep 18, 2007 9:19 pm Post Subject:

Depends very much on the type you buy. I've always found the powerbreaker ones with the 'horizontal blinds' indicator window to need a manual reset after removing power.

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Taylortwocities · Posted: Tue Sep 18, 2007 9:22 pm Post Subject:

That particular PowerBreaker plug is specifically designed to de-operate one power fail and not to re-energise when the power comes back.
This is a specific safety feature used where (eg) long extension leads and cutting machines are in use.

Some stay on if the power fails, not this baby.

I wonder if the OP really wants this though. this would mean that if the power fails when you are on holiday then Nemo and his friends wont have a pump operating until you get back from the scuba diving holiday...

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ben1979 · Posted: Tue Sep 18, 2007 10:32 pm Post Subject:

Why would you want to do that anyhow? Surely you'd want everything to come back up ASAP?

Spark123 · Posted: Tue Sep 18, 2007 11:50 pm Post Subject:

IIRC the type of RCD circuitry which causes it to drop out on power failure is known as an "Active" whereas the type which stay on are known as "Passive".

Steve · Posted: Wed Sep 19, 2007 1:33 pm Post Subject:

I had a plug in RCD (£5 from the orange shed) which would sometimes stay on, sometimes go off. But i think this depends on the type of load with my plug! I appreciate that there are some that are specifically active or passive.

graymo · Posted: Wed Sep 19, 2007 5:22 pm Post Subject:

i need to do this because when the power is off for a few hours, the bacteria dies in the pump, (but not in the tank) and if it comes on again the dead bacteria gets pumped into the tank and nemo and his mates die

.. thnx for all your help peaple.

ben1979 · Posted: Wed Sep 19, 2007 6:48 pm Post Subject:

Ahh, assume it's a marine aquarium then? This being the case, do they not make something specifically for the job?

TicklyT · Posted: Fri Sep 21, 2007 7:16 am Post Subject:

I suppose another approach to theproblem would be to use something like a UPS to maintain the pump during power cuts.

A true UPS would probably be OTT for this application though, as I imagine short breaks could be tolerated.

What would it need to do? run the pump for, say, 5 minutes once every hour?

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bernardgreen · Posted: Fri Sep 21, 2007 11:12 am Post Subject:

The problem of "stale" product in a stalled pump is often dealt with by have a dump valve that opens for a set time whenever the pump is started after a prolonged standstill.

The dump valve diverts the output of the pump to waste so the product in the pump is wasted and some product is used to flush the pump before the valve returns to normal.

In the aquarium pump this would mean only a quantity of water being pumped to waste. A time delay relay operating a three port central heating valve may be all that is needed. Provided the water can be topped up to replace that pumped to waste that might work.

breezer · Posted: Fri Sep 21, 2007 11:15 am Post Subject:

all good advice, but seems ott for as fish tank

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