How do you calculate the multiplying factor of a CT PT meter?
- Normally for voltage, it would be 33000/110 = 300.
- Then must do same for the CT’s ie 200:5 = 40.
- Then scaling ratio or multiplying factor = VTratio * CT ratio = 300*40 = 12000.
- Many utilities leave the scaling within the meter at 1:1 and use the scaling factors in the billing system.
How is CT PT ratio calculated?
Calculate the CT ratio. The CT ratio is the inverse of the voltage ratio. In this example, the voltage ratio is 1:5, so the CT ratio is 5:1. This means the current level is stepped down 5 times where, if the primary current is 200 amps, the CT output is 40 amps.
How do you calculate CT ratio in energy meter?
When analog ammeters are installed, we can easily determine the CT ratio by observing the meter full scale value and then divide that value by 5.
How do you calculate Pt ratio?
You can determine the PT ratio by dividing the phase-to-phase voltage, which is 4,160V, by the voltmeter full-scale range, which is 150V. This simple calculation results in a value of 27.7, which you would interpret as an approximate 28:1 ratio.
Are there any examples of CT and PT calculations?
There are a few examples with CT calculations only and a few examples with both CT and PT calculations. Some of this information is repeated from the CT’s and PT’s page. So, if you have not already checked it out head over there for an overview of what CT’s and PT’s are and their role in metering.
When to use meter multiplier for CT and PT?
Meter multipliers are used when meters are installed in transformer-rated installations. If the CT ratio is 200:5, then the meter multiplier is 40, which is simply 200/5. If a service has both CT’s and PT’s then the two values are multiplied together to give the billing multiplier.
How is the multiplication factor of a meter calculated?
Multiplication Factor (MF) = (200×220 kV) / (1×110) = 400,000 Thus the difference of meter reading must be multiplied by the above Multiplication Factor to get the actual amount of energy imported / exported for our example.
How to calculate the ratio of 200 to 5?
First we need to remember that the ratio of 200:5 can also be written as 200/5 or 200 divided by 5. This is the first calculation that we need to do as this will give us the multiplier. So 200/5 = 40.