3 phase metering

[murdock]

the most common question i get asked about 3 phase meter..."do you save electricity if you balance a 3 phase system" in south africa this is a myth if you have a standard 3 phase meter being metered at residential rates...

when it comes to smart meters for commercial and industrial installation it is a little more complicated.

[AndyD]

Are you pointing out the dfferences in metering between kWh and kVArh?

[murdock]

no andy...i am merely stating that it is a myth that you save electricity if you balance your load ona 3 phase system for a domestic installation in south africa...i am still waiting for a response from the utility to verify this in writting...could take a couple more months

i dont want to got into detail about smart meters...kva metering etc...thats a whole different ball game...for industrial and commercial customers...big money for all the sharks who know a little lingo about enregy saving and power factor correction...unless you use people who know what they are doing...like dudley stevens...chances are you could be in for a small fortune for a system which actually just cost money...because unless you install the the system correctly...it could actually start costing you more...like when you buy a car...do your homework on the maintenace cost...i have a customer who paid a company R100 000 for a ssytem to be installed...within 2 years R60 000 worth of the caps are already damaged...due to incorrect design....eeeeeish...instead of it saving money...the customer is in for another R100 000 to remove and replace the system...gona take 10 years to recover from that before he starts saving...chances are with the rate companies close down...the company will be closed or sold before he starts benefiting...unfortuntely this is a reality and the percentage of comapnies closing down is growing by the day...i am noticing a trend in the good quality services and product companies...because people want cheap junk.

[inusjvr]

murdock if you have a 3 phase kwh meter for residential use it is the same as having 3 single phase kwh meters,no diff. balancing the phases will only avoid overloading a phase causing overloadtripping of the circuit breaker! When it comes to 3 phase kVa metering then it becomes another ball game!

[aquadat0r]

Hi all, just want to check-in again on this.

If I have a 3-phase prepaid residential meter, and only mainly use a single phase with the odd use of oven (on another phase) and geyser (on a other phase), which in principle is a unbalanced system I won't be penalised from a metering perspective? There would be no saving in trying to balance the system or going to a single phase supply?

[inusjvr]

aquadatz0r the meter only reads the power you consume across the 3 phases. There is no penalty or loss for you. Going back to single phase decreases the amount of amps available for you to use in your house. Usualy meters for residential are limited to 60amps per phase so in effect you have 180amps you can use which if you go back to single phase will be reduced to 60amps. The cost per unit consumed is usually charged at residential or business tarriffs. With business tarriff being more expensive per unit consumed. I would stick to 3 phase because it leaves room for more appliances should the need arise.

[Nici P]

I was using a pottery kiln on single phase, and it generally used about 40 units(on my prepaid meter) for 10 hours of firing. I now have the same kiln installed in a house with 3 phase. (The kiln does not require 3 phase to work.)
The meter reading(small meter installed by electrician) is almost double for the same time used?
The kiln draws a max of 30 amps. Any ideas why the units are now doubled? Thanks

[GCE]

I was using a pottery kiln on single phase, and it generally used about 40 units(on my prepaid meter) for 10 hours of firing. I now have the same kiln installed in a house with 3 phase. (The kiln does not require 3 phase to work.)
The meter reading(small meter installed by electrician) is almost double for the same time used?
The kiln draws a max of 30 amps. Any ideas why the units are now doubled? Thanks

To use 30Amps per hour will work out to +/-7 units per hour so for 10 hours 70 units if the elements are on all the time
Could be that previous meter was under reading or the kiln is in a cooler room causing elements to run longer , or in moving a crack has opened up allowing heat to escape and not keep temperature
There could be various reasons

[Derlyn]

I was using a pottery kiln on single phase, and it generally used about 40 units(on my prepaid meter) for 10 hours of firing. I now have the same kiln installed in a house with 3 phase. (The kiln does not require 3 phase to work.)
The meter reading(small meter installed by electrician) is almost double for the same time used?
The kiln draws a max of 30 amps. Any ideas why the units are now doubled? Thanks

Are there multiple elements in the kiln and if so, how many are there and do you know the wattage of each element ?

I'm thinking that if there are multiple elements, maybe at your previous home there were 2 elements connected in series which would drastically reduce the current drawn and now that they are connected correctly, the current drawn is higher ( as it should be).

Another question to ask is ........ are you having to use the kiln for the same amount of time now to achieve the same results as in the past ?
Theoretically, if the kiln is drawing more current, the oven should be hotter and whatever you are drying or curing in the kiln should be completed in a shorter period of time.