Vîna Polarity ya Transformer – Schemaya Rêzik û Wekîkirina Karûbaran
Dua-winding Transformers de Polarity
Dua-winding transformers de, bir windingin bir terminali her an diyerine gore yekem. Transformer polarity induced voltages in high-voltage (HV) and low-voltage (LV) windings de relative direction e refere. Praktik transformers de, winding terminals leads ve brought out, ve polarity defines how these leads connected and labeled.
Transformer Polarity ne Serhildana
Polarity understanding several operational and engineering tasks de critical:
Terminal Markings and Polarity Identification
Traditional dot markings instead of using, it is often clearer H1/H2 for primary (HV) windings and X1/X2 for secondary (LV) windings to denote polarity:
During polarity testing, these labels help identify:
Key Consideration
Incorrect polarity can lead to:
By standardizing on clear terminal markings (H1/H2 and X1/X2), engineers and technicians can ensure proper transformer polarity, enhancing the safety, reliability, and efficiency of power systems.
Transformer Polarity
Dot convention (or dot notation) is a standard method used to denote the polarity of windings in a transformer.
Transformer Polarity and Dot Convention
In Figure A, two dots are placed on the same side of the primary and secondary windings. This indicates that the current entering the dotted terminal of the primary winding has the same direction as the current leaving the dotted terminal of the secondary winding. Consequently, the voltages at the dotted ends are in phase—if the voltage at the dotted point of the primary is positive, the voltage at the dotted point of the secondary will also be positive.
In Figure B, the dots are positioned on opposite sides of the windings, signifying that the windings are wound in opposite directions around the core. Here, the voltages at the dotted points are out of phase: a positive voltage at the primary’s dotted terminal corresponds to a negative voltage at the secondary’s dotted terminal.
Additive vs. Subtractive Polarity
Transformer polarity can be classified as additive or subtractive. To determine which type applies, connect one terminal of the primary winding to one terminal of the secondary winding and attach a voltmeter across the remaining terminals of both windings.
Additive Polarity
The circuit diagram of additive polarity is shown in the figure below.
Subtractive Polarity
In subtractive polarity, the voltmeter measures the difference between the primary voltage and the secondary voltage. Denoted as VC, the voltmeter reading is expressed by the equation:
The circuit diagram of subtractive polarity is shown in the figure below.
Circuit Diagram of Polarity Test
The circuit diagram of the polarity test is shown in the figure below.
Polarity Testing of Transformers
The primary winding terminals are denoted as A1, A2, and the secondary winding terminals as a1, a2. As shown in the figure, a voltmeter VA is connected across the primary winding, VB across the secondary winding, and VC between the primary terminal A1 and secondary terminal a1.
An autotransformer is used to provide a variable AC supply to the primary winding. All voltmeter readings are recorded under this configuration:
Polarity Test Using a DC Source (Battery)
The AC voltage method described above can be impractical for determining the relative polarity of two-winding transformers. A more convenient approach uses a DC source (battery), a switch, and a DC permanent-magnet voltmeter. The connection diagram for this method—including the correct battery polarity—is shown in the figure below.
A switch is connected in series with the primary winding. When the switch is closed, the battery is connected to the primary winding, allowing current to flow through it. This generates flux linkage in both windings, inducing electromotive force (EMF) in both the primary and secondary windings.
The induced EMF in the primary winding has a positive polarity at the end connected to the battery's positive terminal. To determine the secondary winding's polarity:
