Single phase 415volt loads

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In summary, the situation is like this. We have a normal 3 phase installation with 3 single phase Kwh meters. All are connected correctly IE line and load tails are correctly oriented at the meter connections. The meters all turn in the correct direction when normal single phase or 3 phase loads are connected. However, when a single phase 415 volt load is connected (supplied by 2 of the 3 meters) one of the meters will stop and turn in reverse until that particular load is switched off at which time, the reversing meter will resume turning in the right direction. I was wondering if the cause might be due to the power factor correcting capacitor across the 2 phases perhaps. NB this also occurs with single phase 480volt loads where power is supplied by a
  • #1
cnf9115
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When a single phase 415 / 480 volt load is connected, one Kw/h meter will turn in the right direction whilst the other will turn in the reverse direction. This is the case whether the load is a welder or flood light or inductive heater. Can anybody please explain the reason why?
 
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  • #2
Are the "Line" and "Load" connections the same, or if a current sensor is used, they are probably reversed. Otherwise you have provided very little info.
 
  • #3
Hi Windadct, thanks for your reply. The situation is like this. We have a normal 3 phase installation with 3 single phase Kwh meters. All are connected correctly IE line and load tails are correctly oriented at the meter connections. The meters all turn in the correct direction when normal single phase or 3 phase loads are connected. However, when a single phase 415 volt load is connected (supplied by 2 of the 3 meters) one of the meters will stop and turn in reverse until that particular load is switched off at which time, the reversing meter will resume turning in the right direction. I was wondering if the cause might be due to the power factor correcting capacitor across the 2 phases perhaps. NB this also occurs with single phase 480volt loads where power is supplied by a single phase (centre tap) transformer where the output is 2 actives and one neutral.
I hope that this makes it a little clearer.
 
  • #4
Hello Again - best bet will be to develop a detailed diagram of the connections, and visually confirm each connection and polarity. e.g. not how you think or believe it is connected, but how you know it is. I am thinking there is a connection on the wrong phase, etc.
 
  • #5
cnf9115 said:
when a single phase 415 volt load is connected (supplied by 2 of the 3 meters) one of the meters will stop and turn in reverse
Does that reversing meter gives a reading which is the same as the reading of the other meter, though negative, over a set period of time?
 
  • #6
Does that amount to a two wattmeter connection?

Is it possible that with unbalance due to single phase load, one meter legitimately turns backward? And true power is the sum of the two?

Anybody fresh on phasor notation ?

It's not clear to me whether you are describing a system with intermediate voltage taps.
"Meterman's Handbook" is the Bible on this subject - see
http://books.google.com/books?id=ZE...e&q=two wattmeter meterman's handbook&f=false
 
  • #7
I'm hoping the OP answers my question here, so I can then finish the explanation.
 

What is a single phase 415volt load?

A single phase 415volt load refers to an electrical load that operates on a single phase power supply with a voltage of 415 volts. This type of load is commonly used in residential and commercial buildings for lighting, heating, and small appliances.

How is a single phase 415volt load different from a three phase load?

A single phase 415volt load uses only one phase of the power supply, while a three phase load uses three phases. This means that a single phase load has a lower voltage and can only power smaller loads, while a three phase load can handle larger and more powerful equipment.

What are some common examples of single phase 415volt loads?

Some common examples of single phase 415volt loads include refrigerators, air conditioners, washing machines, and small motors. These types of loads typically have a lower power demand and do not require the use of three phase power.

What are the advantages of using single phase 415volt loads?

The main advantage of using single phase 415volt loads is that they are more cost-effective and easier to install compared to three phase loads. They are also suitable for smaller power demands and can be used in residential and commercial buildings without the need for additional equipment.

Are there any limitations to using single phase 415volt loads?

One limitation of single phase 415volt loads is that they cannot power large equipment or high power demands. They are also more susceptible to voltage drops and fluctuations, which can affect the performance of the load. Additionally, they may not be suitable for industrial applications that require heavy machinery.

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