Clamp Meter for Power Distribution in an Indonesian School - Page 1
Forum section: electronics / beginners

author: TonyVov
author_rank: Newbie
timestamp: June 06, 2017, 07:15:59 am
content: Dear eeevbloggersI am working with a school in Bali Indonesia to understand their electrical power load with aim to go gridless and to provide eventually an energy use monitor for students.Most loads are just lights, fans, projectors, computers etc... a few small single phase water pumps almost no airconditioning.We tried with the local electrician clamp meter of the maintenance staff but the 400A range and fat jaws could not read the low power being used and could not fit around most of the smaller wires in the panels. (Looks like mainly 14-20 gauge wires)Grid power is 220V 50Hz 3-phase.Total school load is <30A per phase.Can anyone suggest the best instrument to buy to measure the power (current) load per building.We have about 30 distribution panels in total so typically reading current in range 0-4 amps except the major trunk lines.The local hardware stores only seem to have very high power ammeters with coarse scales so I may have to import something if I can't find it locally.I suspect i require in range from 0.1 - 4 ampsAppreciate any help or guidance on how to measure power usage in this type of situation and what instruments to use.

author: pyroesp
author_rank: Regular Contributor
timestamp: June 06, 2017, 10:04:29 am
content: If the cables are long enough , try winding the cable a couple of times around the 400A clamp meter.Divide the measured current by the number of windings.

author: Jeroen3
author_rank: Super Contributor
timestamp: June 06, 2017, 11:18:08 am
content: Looking at the purpose maybe something ofhttps://shop.openenergymonitor.comcould be suitable?

author: Lightages
author_rank: Unknown
timestamp: June 06, 2017, 12:49:27 pm
content: That was a very clearly explained question. I wish everyone would be so pointed and informative when asking questions here.I would suggest you look at a UNI-T UT211B or UT210E.

author: Berni
author_rank: Super Contributor
timestamp: June 06, 2017, 01:12:41 pm
content: Those UNI-T are fine, another option is the Tenma 72-7222.But 30A per phase seams like not that much for a school. Its pretty common to have thee phase 20A fuses for a regular household here.The main feed to the school i went to was coming in over thumb thick buss bars and that was just one of the buildings, no idea what fuses they had but id be suprised if it was under 200A

author: BravoV
author_rank: Super Contributor
timestamp: June 06, 2017, 01:19:01 pm
content: There alot of cheap KillaWatt (Watt Meter) that are available locally that can measure voltage/current/wattage/watt-hours locally, also imo since each each line is only max out at 4 Amp, these meters are capable of 10 Amps.Just try Tokopedia and search for "watt meter", you'll get tons of results and try find the one that is available nearby you.It uses Analog Devices chip for the main measurement task, used these alot and quite accurate and pretty reliable.It looks like this (random image grabbed from Google) ..

author: BradC
author_rank: Super Contributor
timestamp: June 06, 2017, 07:12:11 pm
content: I've installed a couple of these lately :http://www.ebay.com.au/itm/Single-phase-DIN-rail-power-monitoring-Kwh-Voltage-Current-meter-with-RS485/322537035872I monitor them with a simple rs485 converter like this :http://www.ebay.com.au/itm/Serial-RS232-To-TCP-IP-Ethernet-Converter-Module-HTTPD-Client-Over-LAN-or-WAN-/132197120941?hash=item1ec78ffbadA bit of python to read the modbus registers and poke them into cacti for logging and a separate read into a spreadsheet once a day for billing.Work nicely down below a 1A load and are accurate enough. Certainly as accurate (or moreso) than a generic clamp meter.A different approach anyway.

author: TonyVov
author_rank: Newbie
timestamp: June 08, 2017, 03:59:20 pm
content: Many thanks for reply - unfortunately I can't use a power point insert device - we have 29 external panels all hardwired. I need a meter like Clamp-On type that can sense the current indirectly. My problem is that the local available meters nearby have very large scale range and are no use at low 2-4 amp measure range. most of the the Clamp meters in Lazada, tokopedia and Bukalapac have either high scale range or low information on what is being purchased.looks like i have some good replies in other threads, let me hope my answer pops up.

author: TonyVov
author_rank: Newbie
timestamp: June 08, 2017, 04:01:23 pm
content: Unfortunately we are working inside panel boxes hard wired with buried cables so twisting is not possible. However the idea is great. In the end Googling shows me I can maybe make something home made to work if local resources fail me - thanks for reply.

author: TonyVov
author_rank: Newbie
timestamp: June 08, 2017, 04:04:13 pm
content: Thanks excellent reference site , has showed me that in bigger picture I need something like the Arduino shield or monitor - not just measure. Appreciate you taking the time to reply.

author: Vtile
author_rank: Super Contributor
timestamp: June 08, 2017, 04:19:04 pm
content: I can not recommend you one unfortunately, except that try to find some moderately good quality manufacturer (I wouldn't trust too much the readings on a no-name chinese rebranded meter). Also consider if you need ie. inrush current measuring (ie. motors) ability. Another consideration is if you need also DC or is AC only enough.Have you read through ie. what Farnell do have offer (atleast as research of different kind of models and functionalities).http://fi.farnell.com/c/test-measurement/multimeters-clamp-meters/clamp-metersIe. Beha-Amprope AMP-25-EUR is rather small, TRMS, 10mA resolution (according to Farnells text), have inrush current measurement and low pass filter for variable frequenzy drives.Now there is also special dataloggers (with PC import), for measurement and monitoring of whole buildings, unfortunately the costs of such units goes up fast.

author: BradC
author_rank: Super Contributor
timestamp: June 08, 2017, 04:29:51 pm
content: Here's one. Maybe a generic is available. It has a 4A range and small head.http://www.altronics.com.au/p/q0968-compact-acdc-clamp-meter/

author: TonyVov
author_rank: Newbie
timestamp: June 08, 2017, 04:52:13 pm
content: A lot of online stores in Indonesia sell 200 series 203/204 but so far struggling to find the mini-series 210-211.I will keep digging - thanks for the advice - you have steered me the right way at least.

author: TonyVov
author_rank: Newbie
timestamp: June 08, 2017, 04:57:38 pm
content: Yes - this is a special school - all bamboo - no walls, no AC and very low power use. 450 student International school using less than many residential homes. Seems easy here to get the bigger clamp meters but not the mini-versions. Most people on this Blog would cry to see our panels and wiring - but it will get better. Thanks for the advice.