Electrical engineers have to calculate transformer impedance to ensure efficient power distribution.
Engineers can improve electrical network efficiency and protection by using the right methodology and tools.
Calculating transformer impedance is essential in electrical engineering for constructing efficient power distribution networks.
Calculator
To calculate the transformer impedance percentage (Z %), enter the transformer’s rated primary voltage and primary current into the calculator.
Engineers can ensure that electrical networks run optimally and safely by using the correct methodology and tools.
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What is Transformer Impedance?
Transformer impedance is equivalent resistance provided by the transformer to a path of alternating current.
Why is Transformer Impedance important?
Transformer impedance controls voltage regulation, efficiency, & fault levels in power systems.
How does Impedance affect Transformer Performance?
Higher impedance causes more voltage drop and lesser efficiency, whereas lower impedance causes higher fault currents & losses.
Transformer Impedance Formula
The formula to calculate transformer impedance is:
Z = (Vp/Ip) X (100/%)
Where,
Z – Impedance (in Ω)
Vp – Primary Voltage (in V)
Ip – Primary Current (in Amps)
% – Percentage Impedance
Solved Example
Let’s say we possess a transformer that meets the following requirements:
Primary Voltage (in V) (Vp) – 240V
Primary Current (in Amps) (Ip) – 5A
Percentage Impedance (%) – 2%
Z = (Vp/Ip) X (100/%)
Z = (240/5) X (100/2)
Z = 2400 Ω (Ohms)
What is the Z impedance of a transformer?
Impedance of a transformer can be described as the ratio of a voltage drop across a transformer to the rated current while the transformer is operating at full load. This ratio is used to determine the impedance of the transformer.
It is an essential measurement that shows how resistant the transformer is to electrical current path.
The impedance that is measured in ohms (Ω) is represented by the symbol Z at electronic circuits.
Transformer Acceptable Percentage Impedance as per Indian standards/ IEC 60076
The percentage of impedance that is permissible for transformers according to Indian standards and IEC 60076.
The standard specifies the transformer % impedance for various MVA and kV ratings. However, a variance of +/- 1% is permitted after the transformer is manufactured.
Ex: A 33 MVA, 132/6.6 kV transformer’s % Z is 13%, and its % impedance might range from 13 to 1%. The transformer’s percentage impedance should be between 12.87 and 13.13% when it is tested after production.
