Evening all,
A client has asked if I can have an indication (from within the house) of when the septic tank pump is running, just for the peace of mind that they know that it does actually work!, I can't see anything obvious in terms of an off the shelf product, I'm thinking I would require a type of current monitoring device and a simple light indicating the pump is 'on' or even a figure confirming the amps being drawn. Any suggestions appreciated.
Al
This is a USA site supplying a septic monitor, it monitors the health of the system and gives an alarm if there's a problem.
A panel mounted ammeter is cheap enough and will give an indication that the pump is drawing about the usual current.
A basic kwh meter if observed daily will show if the consumption is normal, even if if the pump is not running at the moment of observation.
A pilot lamp may be wired so as to light when the pump is drawing current, but probably needs to be home made.
if you know the current it takes then a low votlage lamp of the same current and any low voltage would be the traditional method.
With LED lamps and so on it gets harder, but it is still possible - for example if the motor takes 5A then a 3V 5A transformer in series will step up to 240v when loaded with a 15 watt mains lamp.
Or a traditional moving iron AC ammeter in a box.
The slow step is making the hole in the adaptable box the right size.....
Mike
I can not recomend simply connecting a lamp in series with the motor. The starting current will destroy the lamp unless it is so over rated that it wont light at the running current.
Use of a transformer wont help as the starting current is still several times the running current. Also if the lamp fails or is removed then you have in effect a current transformer with an open circuited secondary. This will produce a dangerously high voltage and burn out the transformer.
A home made unit is a possibility. Obtain a four diode, four terminal bridge rectifier. Connect the AC terminals in series with the load. Short circuit the positive and negative output terminals. Connect an MES mains rated pilot lamp holder across the AC terminals. Insert a 2.2 or 2.5 volt torch bulb. ANY current in excess of the bulb rating, and within the rating of the of rectifier, will produce a roughly constant voltage drop of about 1.5 volts and light the lamp. The voltage to the motor is reduced by about 1.5 volts. The brightness of the lamp will vary slightly according to the load, but any load over about 0.3 amps will light the lamp, and many amps will not burn out the lamp.
Alternatively fit a current sensing relay, these are available from china via ebay. The wire carrying the load current is passed through the device but without any direct connection thereto, as in a classic current transformer. An internal circuit closes an internal contact when the current reaches the threshold, which is adjustable. The contacts are mains rated at a very low current, often 0.1 A and may be used to switch a pilot lamp. These units are self powered and require no control supply.
If wifi is available at the point of supply, consider a smart plug
https://www.amazon.co.uk/Knightsbridge-1GAKW-Smart-Plug-White/dp/B088RJ2FT1
or a smart meter
https://www.amazon.co.uk/eMylo-Single-Phase-Electricity-Watt-Hour-Consumption/dp/B083QGBGKK
if wifi is not available, could you instal a wifi bridge? I have a wifi bridge that works well for my garage 100 yards away. The spec suggests that it should work up to 1km.
+1 for a "current sensing relay" approach - they're commonly sold as load shedding relays and you see them incorporated into shower priority units. Usually DIN rail mounting modules, it's easy enough to put them in a simple DIN rail enclosure and wire them up to any indicator you like (you can even get DIN rail mounted indicator lamps, which might be convenient). I've used one in a box along with a couple of trailing sockets to switch on a vacuum cleaner when a power tool is used. Just be careful of the specification and that it'll actually switch with the load the pump presents - some cheaper ones only kick in at about 6A.
- Andy.
There are even self-powered ones with a built-in LED - e.g. uk.rs-online.com/.../8577075
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