sponsor ads

subscribe to INVBAT.COM
Easy to use enter 154 or keyword Quadratic
Ready To Have Your Virtual Assistant - Click Here





sponsor ads

Why subscribe to invbat.com calculator

Buy online State Math Assessment practice test with explanation of the correct answer. Review anytime and anywhere to pass your State Math Assessment test for spring of 2018


Transformer Current Ratio Calculator




Given primary voltage = 69 kV ; secondary voltage = 12.47 kV
secondary current = 1,296.447 A ; Calculate the expected primary current

Vp

Vs
=
Is

Ip

Application of Current Ratio Formula in Estimating Short Circuit Fault Current

Given the normal operational current (ampere) data of 320 MVA , 3 Phase Transformer, 525 / 230 kV as shown in table below.

Estimate the snapshot of temporary transient primary short circuit current, when there is SLG Fault in transmission line primary voltage source due to disturbance using the 10 kV instantaneous voltage drop recorded by PI historian during SLG fault.

Voltages(kV) Amperes
525 Primary Voltage 803.29 Secondary Current
230 Secondary Voltage 351.92 Primary Current
10 Primary SLG Fault 803.29 Secondary Current
230 Secondary Voltage 18,475.67 Short Circuit Primary Current







Vp

Vs
=
Is

Ip





Given the normal operational current (ampere) data of 600 MVA , 3 Phase Transformer, 525 / 230 kV as shown in table below.

Estimate the secondary short circuit current, when the secondary voltage source is shorted and the instantaneous voltage recorded by PI historian during short circuit is 25 kV.

Voltages(kV) Amperes
525 Primary Voltage 1506.18 Secondary Current
230 Secondary Voltage 659.85 Primary Current
525 Primary Voltage 13,856.85 Short Circuit Secondary Current
25 Secondary SLG Fault 659.85 Primary Current


Rationale Behind Transformer Current Ratio

In a no loss , ideal transformer , 100% efficient power transfer is usually assumed.

Power transformer efficiency based on efficiency test report is usually from 95% - 98%. So it is reasonable enough to assume a 100% efficiency.

What does 100% power transfer efficiency means? It means the
power generated in primary winding = power generated in secondary winding

Formula recall of power ( P = I V ).

Power Primary winding = Ip Vp

Power Secondary winding = Is Vs

IpVp = Is Vs

By algebraic manipulation.

Vp / Vs = Is / Ip

By applying this knowledge and using PI historian snapshot value, we can estimate the magnitude of short circuit current and estimate the magnetic forces to the primary or secondary winding of a power transformer depending on where the SLG fault happened. Even better if you have Pi historian data, you can create a streaming data of SLG Fault by using PI expression equation.

INVBAT.COM is helping students, teachers, and employees to create their own customized voice calculator website that will help them to enjoy and not fear a fast coming digital workplace like industrial internet of things and internet of things powered by machine learning, deep learning, and artificial intelligence. Imagine now you can solve similar problem as shown in above example in less than a minute by using your smarthphone, tablet, laptop or desktop computer. This computational speed is not possible before internet and cloud technology.

You might be interested to read more:
So what if I can't remember formula and forget how to use calculator?



Easy to use enter 154 or Quadratic then select search button


Calculator / Formula / Equation you are looking for
As a subscriber you can customize your search keyword or image button



PREVIOUS PREVIOUS




Click here to view available reviewer
Click here to subscribe