Automated switch to cheaper power tariff - Page 1
Forum section: electronics / projects

author: gnif
author_rank: Unknown
timestamp: May 18, 2017, 12:15:48 pm
content: Hi All,Like all I would like to save some cash on electricity where I can... and since my line of work requires running a server 24/7 in my office as one can imagine my bill is rather high. I have two questions, but firstly...I have aZellwegerswitched controlled load, normally used for offpeak water but we switched to gas, so this is completely idle at the moment. The critical equipment I would like to power is protected by a enterprise grade fully online UPS, so any switching delay is not going to cause an issue here, but there is also other miscellaneous stuff on the circuit, including another desktop PC that is not protected by the UPS.1) Does a device already exist that is legal in NSW Australia that can automatically switch a circuit between two tariffs as one is (de)energized?2) And if not.... would it be legal/safe/wise to setup the following:Install another DIN panel to keep this all separate simply for organisation.Install a 2P 10A breaker, feed each tariff into them.Install a DIN mount 240V DPDT 10A relay with a 240V coil.Connect the controlled tariff to the coil, and one of the relay inputs.Connect the normal tariff to the other relay input.Power the circuit from the relay's output.If this would be legal and safe, a few questions:1) Would it be advisable to build a circuit that detects the 0v crossing and chose that moment to energize the relay (triac?) to minimize the switch over and any possible arcing in the relay?2) And if so, what method would be recommended?Note: I am not a qualified electrician, I know I am not allowed to touch this stuff without the certification... I am asking this as I could build it all and have a qualified electrician inspect and install it for me

author: flynwill
author_rank: Regular Contributor
timestamp: May 18, 2017, 01:44:17 pm
content: Here in the US the device you seek is referred to as an "Automatic Transfer Switch". The typical application is to switch the load to a standby generator should the mains fail. (And they usually include control circuitry to start said generator). But it would work in this situation as well. They come in all sizes, although I don't think I've ever seen as small as 10A.As to the legalities I can't say. It would seem to me you are "cheating" on the controlled tariff.

author: gnif
author_rank: Unknown
timestamp: May 18, 2017, 02:59:19 pm
content: Quote from: flynwill on May 18, 2017, 01:44:17 pmThanks! That gave me something to search on and get some better understanding of what is available.Quote from: flynwill on May 18, 2017, 01:44:17 pmWe are encouraged to use the controlled tariffs for cheaper energy, we can in fact opt to use 'Controlled Load 2' which turns on at 5PM and off again at 8AM, instead of 1:30AM-7:00AM. Technically I can have an outlet wired for Controlled Load and just unplug my stuff from it into the standard output during the normal period manually, I just want to make this automated and quick enough that my equipment isn't interrupted.That said, looks like a 10A 2P breaker and a 240Volt 20A 2Pole - 1NC + 1NO - Din Rail Contactor are the way to go... I would also install a power meter with an isolated pulsed output for each tariff so that I can log the usage of each (I like graphs).

author: BrianHG
author_rank: Super Contributor
timestamp: May 18, 2017, 03:20:07 pm
content: I'm not sure I understand,A) You have 2 set's of AC sources, 1 only switched on during off peak hours which is on a different meter?Or,B) You are being charged less during off peak hour from any outlet?If (A), wouldn't is be cheapest to run an online USP which can power your system during the disabled peak day period, then, charge during the off peak hours? Though you need 9 hours, and preferably a massive super-cap bank since you would be cycling every single day.

author: gnif
author_rank: Unknown
timestamp: May 18, 2017, 03:23:10 pm
content: Quote from: BrianHG on May 18, 2017, 03:20:07 pmIt is really only one AC source fed through two meters, one meter is the peak rates, the other is off-peak rates and is switched by the power company remotely. Normally in Australia unless you have had it done otherwise the offpeak is wired to just the hot water and/or in slab heating, but you can request an electrician to wire up an outlet also if you like. In my case, it is currently not feeding anything at all.

author: BrianHG
author_rank: Super Contributor
timestamp: May 18, 2017, 03:36:59 pm
content: As for switching between 2 metered sources, I think the big-ass DPDT relay would work, with common GND & a simple power filter power bar before you feed your servers. I've made a home-made UPS with a simple high powered inverter and such a switch right at my fuse box for the first level of my house, and with some LED lights, you can catch a blink with the switch-over, but, my PCs didn't feel a thing. I was in a power-failure prone area.When it comes to using Triacs, you will get much cleaner performance, but, you will want this switch circuit to be in phase with the 2 AC sources, & in-between the 2 fuse boxes, otherwise you will be in for a nasty surprise the moment 1 side triac doesn't break before making the new switch side turns on which can happen all too easily.Now for the other warning I must give you, besides playing with mains is dangerous, having any home made equipment connected to your mains, if anything happens in your house or apartment, a fire, electrical injury or death, if your house insurance investigation finds you had such a home made uncertified mod wires into your home AC, whether if it is responsible or not, you will not see a penny.

author: gnif
author_rank: Unknown
timestamp: May 18, 2017, 03:45:19 pm
content: Quote from: BrianHG on May 18, 2017, 03:36:59 pmThanks for the info... Phase wont be an issue since there is really only one power source that is split to run through the remotely triggered switch and the secondary meter, but even still I don't think I will bother with trying with triacs, for two reasons.1) Someone might complain, legality, insurance, etc...2) I found a perfect "Contactor" for the job... turns out they don't call these relayshttp://nixon-dce.com/index.php?route=product/product&path=72_152&product_id=656Just tie A1 to neutral, and A2 to 2, which will have the switched tariff on it.

author: BrianHG
author_rank: Super Contributor
timestamp: May 18, 2017, 03:47:38 pm
content: If you want the clean certified method, you might look for something cheaper than this:http://www.wti.com/p-167-pts-9cm20-2r-automatic-power-transfer-switch.aspx

author: gnif
author_rank: Unknown
timestamp: May 18, 2017, 03:52:39 pm
content: Quote from: BrianHG on May 18, 2017, 03:47:38 pmYes, it would be great if I could get one for cheap but if I can build a little box that does the same thing for cheap (~$100AUD), and I can get an electrician to confirm is ok it seems like the better path to go. I have some friends who are qualified who would be willing to take a gander at a prototype if I assemble one.

author: BrianHG
author_rank: Super Contributor
timestamp: May 18, 2017, 04:00:27 pm
content: Here's what to google for "Transfer Switch PDUs".Here are some from Tripplitte.https://www.tripplite.com/products/power-distribution-units-pdus~15?1692=Switched&creative=177285090851&keyword=%2Bswitched%20%2Bpdu&matchtype=b&network=g&device=c&gclid=CjwKEAjwjPXIBRDhwICRg-DbgHISJADP6QXpe_oam9BjmH9jhYxe1lT-3ta6FzXFQ8e-eV8g3iEf3BoC0cfw_wcBMaybe cheaper other brands.Some even come with network power metering for logging consumption, but they cost more.It will still be cheapest for a home made solution, of look into marine/camper Transfer Switch PDUs which are in to 50-100$ range.

author: gnif
author_rank: Unknown
timestamp: May 18, 2017, 04:06:00 pm
content: Quote from: BrianHG on May 18, 2017, 04:00:27 pmCheapest that Tripplite sell that will suit Australian voltages is the PDUMH15HVAT, at nearly $500AUD.

author: BrianHG
author_rank: Super Contributor
timestamp: May 18, 2017, 04:12:04 pm
content: I wonder if a 240v version of this guy exists:https://www.amazon.com/CyberPower-PDU15M10AT-Metered-Power-Distribution/dp/B00NEHUX08/ref=sr_1_1?ie=UTF8&qid=1495123830&sr=8-1&keywords=CyberPower+Metered+ATS+Power+Distribution+Units218$, plus is has power metering.

author: gnif
author_rank: Unknown
timestamp: May 18, 2017, 04:15:00 pm
content: Quote from: BrianHG on May 18, 2017, 04:12:04 pmRemember, that's not AUD too, $218USD is $293.38AUD. These devices would be nice, but they simply are not in my budget at the moment, I thank you for your suggestions but at this time I am just looking for input from someone qualified as an Electrician in my area to confirm if the concept is even viable in the simplest form (the contactor).

author: tautech
author_rank: Super Contributor
timestamp: May 18, 2017, 04:59:09 pm
content: The only issue I see with a simple solution (contactor) is the twice daily interruption of the mains and how your UPS is going to like this as an ongoing basis.If the UPS switching is electromechanical and it might legally have to be, can the relays hack this ?Or will the ms switching time of an NO-NC contactor be fast enough for the UPS not to notice ?I think I'd like addition isolation for safety, a 2 pole master main that isolates both supplies from the switchover HW.

author: Towger
author_rank: Super Contributor
timestamp: May 18, 2017, 05:38:56 pm
content: I am assuming you still have one incomming supply?In this part of the world you can have Night Saver Electricity (Economy 7 in the UK), where you have two meters (or one meter with two displays). One for day time rate and the other for a cheaper night time rate. It is only worth your while if you use a lot of electricity during the night, such as having electric storage heaters as the 'Standing Charge' for having the two meters is more expensive.Anyway it is on the supply to the whole building, and the supply is switched between the two meters via 'make before brake' contactor, traditionally controlled by a seperate clock.This has no interruption to the supply in the building.

author: MagicSmoker
author_rank: Super Contributor
timestamp: May 18, 2017, 05:50:03 pm
content: Hmm... if I understand the situation correctly, you have a single AC feed that is split between two meters and one of those meters has a utility-controlled shutoff switch inside it with the benefit of a lower billed rate. You want to power the servers from the switched meter to get the lower billed rate but, of course, servers need to be powered all the time so when the switched meter is turned off you want to automatically changeover to the unswitched meter, correct?EDIT - stupid keyboard mistake resulted in this getting posted before I finished...

author: Nusa
author_rank: Super Contributor
timestamp: May 18, 2017, 06:14:25 pm
content: It occurs to me that if whatever solution you come up with is not permanently wired-in, you may not require an electrician. That means something that PLUGS into both circuits, and has OUTLETS for equipment to plug into. Depending on what AU law says about that, of course. Also assuming you can do it correctly and safely for your situation.As for equipment that's not protected by your UPS, you may need to acquire a cheaper consumer-grade UPS for them to survive the burp.

author: Someone
author_rank: Super Contributor
timestamp: May 18, 2017, 09:51:53 pm
content: Controlled load is limited to "approved" loads, and now requires permanent connections (no power points allowed). So you'd need an electrician to install it and you'd need to ask the supplier for approval. I'd say you've got Buckleys chance of getting a UPS on it, and even with the cheaper tarrif the costs of storage (battery wear etc) are unlikely to pay back.

author: gnif
author_rank: Unknown
timestamp: May 18, 2017, 10:18:04 pm
content: Quote from: Someone on May 18, 2017, 09:51:53 pmI am not able to find any information on there being approved loads, in fact, I find quite the opposite:https://www.energyaustralia.com.au/home/electricity-and-gas/understand-electricity-and-gas-plans/what-peak-electricityQuoteI will give them a call today and see if they can give me a clear answer on this.Re make before break, yes that would be ideal, but the problem is detecting when it is about to occur... its controlled by the powersupply and the time varies by up to an hour each night (my UPS doesn't like the injected remote control signal on the line and alarms each switch over). As for longevity of the UPS, it already is switching twice daily due to the control signal anyway, but since it is a fully online UPS it doesn't really matter much to battery life at all.

author: tautech
author_rank: Super Contributor
timestamp: May 18, 2017, 10:41:04 pm
content: A "switched on" sparky will have an immediate idea if this is allowed. Your "switched" supply sounds like our water relay ripple switch in NZ and AFAIK only water heaters are allowed to use it.We have a # if different tariffs in NZ including some for off peak loads and IIRC they need be on approved and sealed timeclocks.Each provider offers different tariffs so you might have to shop around.

author: peter.mitchell
author_rank: Super Contributor
timestamp: May 18, 2017, 10:47:06 pm
content: i've looked into it before, I wanted to put a clothes drier and washing machine on it to run over night - turns out that the controlled load circuits must legally be only for hard wired loads, so you can't wire to a socket; I guess if your UPS was hard wired you MIGHT be able to get away with it...This posthttps://rechargingnsw.com.au/charging-your-ev-or-phev-from-controlled-load-or-off-peak/4at some stage in the past cited an ausgrid document saying that it is fine for a hardwired but obscure load to be attached to controlled load 1 or 2.

author: gnif
author_rank: Unknown
timestamp: May 18, 2017, 11:23:42 pm
content: Ok, thanks everyone for your input, I managed to get a final ruling on this...1) It is legal to connect only approved devices to it2) The devices must be hard wired3) A switch-over to the non controlled load of any kind is not permitted.http://www.endeavourenergy.com.au/wps/wcm/connect/2cf31e74-cf62-465a-b0c0-f1ff065e8987/NUOS+Price+List_201617_v3.pdf?MOD=AJPERESQuote

author: tautech
author_rank: Super Contributor
timestamp: May 18, 2017, 11:29:57 pm
content: Quote from: gnif on May 18, 2017, 11:23:42 pmHow could they possibly know or find out if you implemented it.

author: gnif
author_rank: Unknown
timestamp: May 18, 2017, 11:58:33 pm
content: Quote from: tautech on May 18, 2017, 11:29:57 pmI know right! It's such a joke since electrically there is no reason why you can't do it.

author: tautech
author_rank: Super Contributor
timestamp: May 19, 2017, 12:43:11 am
content: Quote from: gnif on May 18, 2017, 11:58:33 pmMuch the same as bypassing controlled water heating..........just don't get caught.

author: Someone
author_rank: Super Contributor
timestamp: May 19, 2017, 01:13:05 am
content: Quote from: gnif on May 18, 2017, 10:18:04 pmYou're getting information for the consumer time of use (TOU) tariffs which don't have the changeover relay or separate meter but use time stamping from a smart meter to allow the retailer to provide arbitrary tariff structures. Compare the difference between the controlled load tariffs of 31 and 33:https://www.ergon.com.au/retail/business/tariffs-and-prices/small-business-tariffsWhere they turn the power on and off to suit their supply/demand balance and will only let you install benign loads. Unlike the 22A general time of use which is a consistent connection which changes price by time of day.Quote from: tautech on May 18, 2017, 11:29:57 pmWhen they notice your drop is pulling huge amounts over overnight power and very little during the day and it doesnt match with their models, they know what the controlled loads are and have budgeted for their size. Also power abnormalities like that appear like a grow op, good times when your door gets kicked in by the police. Its stealing plain and simple, why not just run an extension cord from next door because they are on a cheaper tariff and also save on the daily supply charge?

author: gnif
author_rank: Unknown
timestamp: May 19, 2017, 01:15:09 am
content: Quote from: Someone on May 19, 2017, 01:13:05 amWhich is why this thread was about finding a legal way to do this, there is clearly no legal way and as such wont be done