Backyard Aquaponics
A place to discuss aquaponics

Coles I think.

I have a three phase contactor floating around here somewhere (one of the legs is burnt out), I will see if I can find it. I should only need one leg/phase working.

Nova

Nova just be aware of two things, the main 3 phase contacts are N.O., you need to use one of the aux. N.C. contacts.

Also the coil will either be 24V or 240V, will need to check if 12V coils are available if you wanted to use low voltage.

Nova, use this realy if you want to use a plug pack to run it. low voltage so its safe, and the relay itself will switch upto 20A DC at 12V. It has both NO and NC contacts

And its cheap

http://www.dse.com.au/cgi-bin/dse.store ... View/P8035

That is definately Dick SMiths and Jaycar for you. I( always get blank looks when I go in their stores... I don't bother with Dick Smiths anymore. We have a store called Altronics in Perth. They definately know their stuff. www.altronics.com.au Delivery is not too bad. Check them out.

As for a regular realy, the way you would do it means the coil is going to be 'energised' 99.99% of the time. Now relays are rated for many thousand operations. However all it takes is one power surge and the coil in your relay can be fused or shorted thus losing your backup completely.

I would stongly recomend using a voltage sensing to trigger a relay or make use of the contactor if you can. If it doesn't already have a resetable circuit breaker I strongly recommend installing one in circuit. Get one rated 15% greater than the coil current. This will protect your relaya bit.

OK buy the three items linked to below, and you have a power fail back up bubbler for $30

(air pump) http://www.ageofaquariums.com.au/category32_1.htm (air pump)

(relay) http://www.jaycar.com.au/productView.as ... &SUBCATID= (relay)

(plug pack) http://www.jaycar.com.au/productView.as ... BCATID=521 (plug pack)

The air pump runs on standards batteries.

Proceedure:

1) Open the pump

2) cut one of the wires that goes from the battery terminal to the actual pump. (it doesn't matter which one)

3) extend the two ends of the now cut wire out side the casing

4) connect one wire to the "common" pin of the relay (C)

5) connect the other wire to the "Normally Closed" pin of the relay (NC)

6) Cut the plug of the plug pack (NOT THE POWER POINT SIDE) and connect one wire to each side of the coil of the relay

Job done. Anyone with a pair of side cutters and a few crimp connectors can do this. And becasue you're working with batteries and a 12V plugpack its safe, even if you somehow stuff it up

Steve

I pressume the same procedure could be used with a bigger battery and pump Steve.

Sure can!

thanks Steve - that is what most of us have been looking for

thought so

Here is such a device, cost of parts and to pay an electrician to wire it up 76.00.
Easy to wire yourself but if you did it wrong and killed somebody ......
To keep to that price I have to get 10 done at a time.
Cost much more for the electrician if only one offs.

While there is 240 volt power the relay is held open,
when 240 volt goes off the relay closes and 12 volt power flows through from battery/charger to the aeration device.
Cost for bilge pump and defuser head around 40.00
My choice of aeration device is a 12 volt marine
bilge pump sending water through a small upright with a defuser spray head at the top creating a waterfall effect thereby
breaking the water surface.

The bigger the battery the longer the standby device will run.

Muzza

Unless you have someone in mind.

I've been thinking about backup aeration for my system & I have a couple of questions:

1. Is there a formula (or guideline) for how much aeration (LPH) I will need?
2. Someone told me that a UPS will likely output a SQUARE wave, not a sinusoid & that while computer power supplies can handle this, an air pump may not be able to. Will any 240V air pump work with a UPS?

they do work, sound noisier and output a little less volume.

Monya
If you need a hand, let me know. I'm happy to swap electronics know-how for AP tips!