# General Business Category > Technology Forum >  Mains voltage logger

## duncan drennan

Does anyone know of a cost effective mains voltage logger that can either download or be connected directly to a PC? It should be able to do both single and three phase measurements.

My dad is having a problem at one of their clients, and they want some info to back them up in their dispute with the municipality.

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## Graeme

I borrowed a mains voltage logging device years ago when electric motors on my property started burning out.  The device produced a graph on a roll of paper that gave a continuous read-out of the voltage at my home.  The graph looked like all the proof I needed to have the local electrical distributor pay for the burned-out motors.  Alas, the response was that the reading did not coincide with the dates on which the motors packed in, and the device had not been calibrated.  I was getting all set to take further readings and take the distributor to court when a friend in the legal profession warned me that the distributor would go to any lengths and any cost to repudiate my claim.  I took his advice and abandoned the attempt. 

If you use one, make sure you get a certificate of calibration before and after you use the device.

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## murdock

i think i was or still am the only electrical contracting company in south africa who owns a fluke 435 which is a class A unit which can be used in court  a battle against the municipaliy if there is a dispute...and i am in the process of investing in 5 amp cts for metering as i have found a demand for this kind of work especially in high voltage systems.

there is no other instrument that i know of which has the accuracy of the 435...i could be wrong.


ther is a company in westmead who say they specialise in metering called EVT  i dont have the details but i am sure you will find their number in the book.

there are lots of intrument out there which can measure KWH but how accurate they are and whether or not you would have a case against the municipality i cannot answer that question.

the cheapest option would be just to buy a kwh meter from your local electrical wholesaler and connect it up and see if the read out is the same...just make sure the cts are the same ratio etc.

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## murdock

the contact details for EVT 031-7008212 or cell 0836516577 email evtech@yebo.co.za

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## murdock

all my equipment is calibrated on a yearly basis which is requirement for most fluke products.

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## duncan drennan

The dispute is in East London, and has to do with voltage levels, not kWh.

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## murdock

the cheapest unit i know of which can do what you want to do cost about R14000.00 3 phase...a fluke 289 can record min/max /avg but only single phase.

you get a K5020 from major tech if you are looking for cheap.

or you can get a 1735 which is the bottom of the range from fluke which will set you back  about R30000.00 

the municipality should have recorders which they can fit and record.

there must power quality experts around there...your local electrical wholesaler should be able to assist you with this problem.

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## AndyD

If you need to log basics such as voltage, current, real power, apparent power, reactive power, phase failure, power outages, power factors, maximum demand etc etc and you need a cost effective data logger that will stand up in court (class 1 accuracy, Orbis compliant data capture, and calibration certified) then I would suggest use a consumption meter with logging capabilities. Here's a local three phase unit that retails at under three thousand Rands. It has adequate resolution and memory for at least a month of logging at its highest settings. For just voltage logging you don't need CT's or VT's so that would be the total cost. If you want to log currents or power figures then a set of 3 x split 5 Amp CT's of metering accuracy will set you back another R1500 - R1800 for all three (<500Amp). It will record under voltage events as alarms with complete info about event start and finish times, event duration as well as the actual voltages recorded. It comes with free capture software and will export directly int Excel for graphing. I doubt you'll find a simpler or cheaper solution that will stand up in court.

If you need more complex logging such as harmonics or you need to capture waveforms for analysis then you'll need to go to the party with something more convincing. The cost of these types analyzer units will be 20 - 30 thousand Rands and upward.

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Dave A (16-Feb-10)

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## murdock

this could be interesting...with the electricty increase of 35% coming into affect soon...and considering it has become our biggest household expense...i will be looking at converting to a pre paid meter so that the bill doesnt run away like it is at the moment.

My PQA equipment is too expensive to leave recording for long periods of time this could be a cheaper option to leave on site.

i am just too busy at work to look into my electricity consumption and ways to improve and lower useage.

anyone looked into gas options...are they going to be cheaper when the electricity is increased...or i am gona have to build a fire place and fit a donkey for hot water and braai every night :Big Grin:

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## AndyD

> anyone looked into gas options...are they going to be cheaper when the electricity is increased...or i am gona have to build a fire place and fit a donkey for hot water and braai every night


Well with the increase in electricity price I can see a steady increase in gas demand happening over the next few years. I doubt it will be immediate but as people replace equipment such as heaters and cooking appliances then they will consider gas more and more as an option. Will the increased demand for gas result in it's price increasing? Probably, so the donkey may be the way to go ;-)

Like you say, leaving you PQA equipment on site can be risky, at least with four grands worth of kit the insurance won't be so high and even if it's not insured it's not the end of the world if you loose one each year to theft. I wouldn't say the same for your Fluke PQA though. Also at 2-3 thousand Rands it's hardly worth sending them in for calibration every year, you might as well just buy a new one.

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## hardwic

Hello to the forum.

I Realize this is an old thread but reading it, I thought some maybe interested.

I have been working for a while now to optimize my own power consumption.
In doing so, I used my Fluke 287 and Scopemeter 199 to do most my initial monitoring.

I realized that to correctly save, you have to know what you are using and what the mains condition is like.
The Fluke kit is not ideal to be left dedicated to this task so I built my own.

The system comprises of a 16mhz CPU (Atmega128) with 8 AD converters and real time clock.
Initially the plan was to have 1 voltage input and 7 current sensors.

I then realized that having a real time graph of you main phase is actually all you need so I only equipped 2 CT's and 1 voltage sensor. I was not targeting 3 phase but the concept will apply.

Anyway the point is I know have Real power graphed in this minute, this hour, last 60 hours.
It also show power factor, wH, voltage, current, price and voltage/current waveform.
The output compares very well with the Fluke 199 considering I only have 16mhz and can only do 1 AD conversion every 3 cycles.

I considered adding a SD card for logging but dropped the idea because the graphs where more than necessary. Comments in this thread are making me think this is requirement.
Any suggestions of other features welcome.

The legal aspects of being able to use this data in court was never my intention because even top of the range kit can be discredited in court for many reasons. The intention was to make this information available/affordable so that it could be left in place in the average home permanently.

To give you an example, my house normally idles at 300Wh at around 230V. The last few days the mains voltage has been up at 247V and my idle consumption is sitting at over 500Wh.
So I know suspect I am paying more due to the high mains but my load is the same!

I didn't think there was actually a market out there though as most people don't care/understand. This thread has me thinking otherwise though.

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## AndyD

A nice little project by the sounds of it, sounds like it was a great success. There's a fairly new product that will do this and also connect to your computer to give you graphing etc. The Owl monitor; see here  http://www.radiant.co.za/index.php?p...08&sc_id=308-8 It won't give you realtime monitoring results however but it certainly simplifies it for the average home owner who isn't up for building a DAQ setup from the ground up.

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## NTS2011

Hi Duncan,I have just completed some consumption investigations which involve the local Municipality.If you looking at not spending a lot of money, then ascertain the following.
(a)What is the make of meter that the Municipality is using? Normally you can contact that company and procure the same meter or even a test meter.
(b)Make sure that it has a valid calibration certificate. This you can get from Eskom or even the Test and Metering section of the Municipality with which you have a dispute.
Attached is a sample of a load profile that I took recently. The meter that was used is the same type that the Municipality uses.

Hope this help somewhat.

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## hardwic

AndyD, I have looked at both the Owl and MieO. Both are very basic and provide a very basic estimation. They don't even measure voltage and assume it to be a constant.

The last few days my voltage has been sitting at 247Vac, today 223vac. They only read apparent power. They only update evert minute or so. 

I wanted what a fluke 199 could display but 25 x cheaper, I think I've got there.
You can't compare 2gb sampling 5k sampling though but for 50 hz there is no problem.

Logging stats is not a problem but providing a certified product will change the target price of R1k to more like R10k. I don't even know if people will buy at R1k :Embarrassment:

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## hardwic

These are screen shots of the item. The layout is a bit crude at present but I am more interested in the values for now than prettiness:
Main screen 

voltage and current waveform

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## hardwic

I am not sure about the Municipality. At 1 point I complained about the quality of my inbound mains. A truck came around and they had a screw driver.
The used my fluke 287 but when I showed them the reading on the scopemeter 199, they new nothing..

Basically all the local guys know is:
1) are the lights on
2) are the lights flickering..

I am sure there must be some high level guys there somewhere but they are well hidden.

Anyway you will never win a dispute with the council, they will just refer it to legal and besides they have a max liability of R1000.
The idea was to have a device that you can use to correctly manage your usage which would accurately reflect what council meter says.

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## murdock

i have a small problem in a building used by an IT company...i have a piece of equipment installed on site to prevent a disaster again where they cut the neutral cable and blew the living daylights out of all their equipment...now we have a bigger problem because the voltage is so unstable that it keeps dropping out the contactor...i have it set to 190 and 250 volts and it stills drops out...

so i connected my fluke 435 to the system to find the voltage drops as low as 181 volts at any given time...so i contact the durban electricity department...get 5 phone calls from various people who have been to site to sort out the problem on the same day...i sit months later still with the same problem and no answers.

when i asked the one so called sparkie what he was using to test the voltage i was told he had a multimeter...i can only shake my head and bang it against my target on the back of my office door...and take more medication to keep calm...when i approuch the electricity department to offer my service unfortunately i am not the right colour and am only 100 % BEE so i cannot assist then.

so we have taken other measures to improve the volts stability.

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