ADVICE NEEDED... FLOAT SWITCH MODULE WIRING! - Page 1
Forum section: electronics / beginners

author: o04n7h0n90o
author_rank: Newbie
timestamp: June 21, 2016, 10:36:07 am
content: Hello everyone this is my first post, I am but a humble novice in need of your electronics knowledge and expertise... Which will be greatly appreciated of course!I have bought a device that consists of a bucket with a water inlet at the bottom, inside there is small water pump and a float switch which are wired to a small junction box that is fixed to the outside of the bucket.As water fills the bucket the float switch activates the pump which then pumps water out of the bucket to where I need it.So I decided to take a look inside the junction box to see exactly how it is wired.My thinking was that it would be as simple as the float switch wired to the live of the pump and simply functioning as a switch to activate the pump when the water level rises.However to my surprise there is a module in there, and I can't figure out what it would be doing there or why it might be needed and purpose it serves, so thats how I ended up here.Can anyone shed some light on what this module could be doing or why it might be needed?Thanks in advance!

author: Ian.M
author_rank: Super Contributor
timestamp: June 21, 2016, 10:55:53 am
content: Modern float switches are no longer permitted to use a Mercury capsule so usually cant handle the pump motor current directly as they tend to be based on a ball bearing tilt switch inside the float 'flapper'. If its a higher quality one with a magnet in the float and a reed relay in the fixed part, it also wont be able to handle much current. The module probably simply acts as a solid state relay.

author: o04n7h0n90o
author_rank: Newbie
timestamp: June 21, 2016, 11:03:37 am
content: Hi Ian thanks for your quick response, the switch is the higher quality one as you said, the spec sheet says 1 amp and the pump uses only 13 watts @ 240v, Im just resizing some more photos to upload.

author: o04n7h0n90o
author_rank: Newbie
timestamp: June 21, 2016, 11:10:33 am
content: Some more pics attached

author: dr_dan
author_rank: Contributor
timestamp: June 21, 2016, 11:15:23 am
content: It looks like the module allows you to set the minimum run time for the pump when the float switch triggers. It adds some hysteresis to the system, without it your pump would be forever switching on and off with the float near the high-water mark.

author: Ian.M
author_rank: Super Contributor
timestamp: June 21, 2016, 11:17:59 am
content: The float switch is only rated for 15W. That means that it can only switch 15V at its full 1A rating, or 60mA at its maximum working voltage of 250V. Pushing the limits of the switch rating is likely to shorten its life by an order of magnitude.13W will be the pump's continuous power consumption at specified flow rate and head. Its likely to use a lot more power transiently during startup, maybe as much as ten times more.

author: o04n7h0n90o
author_rank: Newbie
timestamp: June 21, 2016, 11:30:38 am
content: Thanks you all for your repliesI am thinking of making one of these myself to save money...So my thoughts are to use a relay to protect the switch, do you think that would be good practice?Also any ideas on how i could copy what the module is doing without actually having one?Perhaps I could use a time delay switch or something similar?Your input would be appreciated!

author: bitslice
author_rank: Frequent Contributor
timestamp: June 21, 2016, 11:41:22 am
content: this is a slightly more modern equivalentabout £3ebay(Liquid Level Controller Sensor Module Water Level Detection Sensor Low pressure)I was looking at this just last night, I was wondering if the intended sensor inputs (using capacitance as a trigger), could reliably be replaced with two conventional reed float switches.I reckon capacitive sensors would just corrode, even though I'd be sensing distilled water.Personally I'd rather time the period used to empty a container once a high level was reached, rather than the shut-off requiring input from another (now at low level) sensor. One less thing to go wrong.

author: o04n7h0n90o
author_rank: Newbie
timestamp: June 21, 2016, 11:59:20 am
content: That's interesting I will take a look thanks not to sure how I would wire it up for my needs tho?

author: o04n7h0n90o
author_rank: Newbie
timestamp: June 21, 2016, 02:18:34 pm
content: I found a multifunctional relay... could this be configured to work? any thoughts??

author: bitslice
author_rank: Frequent Contributor
timestamp: June 21, 2016, 02:46:07 pm
content: Quote from: o04n7h0n90o on June 21, 2016, 02:18:34 pmI wouldn't pick that exact one as it's likely to be expensive, but there are similar on eBay as above, probably under "timer cycle delay module"what you are trying to do is to have a trigger input (float switch) initiate a timing cycle, which waits for a few seconds, then turns on the (pump)relay on for say 30 seconds, and then turn it off.So for that relay, maybe the "Function: Delay on Make/Break" mode