Power transformer nominal power, voltage, current and other parameters of the mark, long time, will fall off or disappear. Some commercial transformers do not mark any parameters. This caused great inconvenience to use. Here are unmarked power transformer parameter checking. This method of purchasing power transformer is also a valuable reference.
First, identify the power transformer
1. Identify common power transformer from the shape of the core are two E-shaped and C-shaped. E-shaped iron core transformer was shell structure (core wrapped coil), with D41, D42 for high-quality silicon steel core, wide range of applications. C-shaped cold-rolled silicon steel core transformer with a core band for the magnetic leakage, small size, were the core structure (coil wrapped iron core).
2. Winding leads from the terminal identification number of the power transformers commonly have two windings, that is, a primary and a secondary winding, so there are four terminal. Some of the power transformer in order to prevent hum and other interference, the primary and secondary windings are added a shield between its shield is ground. Therefore, the power transformer terminals is at least four.
3. Way from the silicon steel sheet of laminated identification of E-shaped power transformer silicon steel sheet is inserted cross *, E tablets and I do not leave blank gap between films, the entire core match exactly. Audio input and output transformer E tablets and I film a certain air gap between the left, which is different from the power and audio transformers for the most intuitive way. The C-shaped transformers, power transformers generally.
Second, the estimated power
The size of power transformers transmit power depends on the material and the core cross section. The so-called cross-sectional area, whether it is E-shaped shell structure, or the E-shaped core structure (including the C-shaped structure), are means that part of the package winding the core column cross-section (rectangular) area. In cross-sectional area S measured after the core can be estimated by P = S2/1.5 transformer power P. Type in S unit is cm2.
For example: a power transformer measured core cross-sectional area S = 7cm2, estimate its power, was P = S2/1.5 = 72/1.5 = 33W? Removed various errors, the actual nominal power is 30W.
Third, the winding voltage measurement
For an unmarked power transformer utilized to identify the primary winding, and distinguish between the output voltage of the secondary winding is the most basic tasks. Are examples of one method to judge.
Example: given a power transformer, a total of 10 terminals. Try to check the winding voltage.
The first step: to distinguish the number of winding groups, draw circuit diagrams.
R × 1 block with a multimeter measure, where a winding shall be connected to terminals. Are measured: 22 connected with 3 groups, there are a group of three connected, and a terminal with no links to any other terminal. According to the measurements, draw the circuit, and number.
Known from measurements, there are four windings of the transformer, which label , , is along the winding tap, No. terminals are not connected with any of the winding is shielding Lead terminal.
Step Two: Determine the primary winding.
The buck power transformer primary winding diameter smaller, more turns than the secondary winding. Therefore, such as step-down transformer Figure 4, the largest of its primary winding resistance.
Step Three: Determine all secondary winding voltage.
Winding on the primary access through the AC voltage regulator, slowly step up to 220V. Followed by measurement of the winding circuit voltage, indicated on each output. If the transformer no-load condition in a long time without heat, indicating transformer performance largely intact, but also further validate the judge's primary winding is correct.
Fourth, the secondary windings to determine the maximum current
Transformer secondary winding output current depends on the diameter of the enameled wire winding D. Enameled wire diameter can be measured directly lead wires Department. After measuring the diameter, according to the formula I = 2D2, can be obtained the maximum output current of the windings. Type in the D unit is mm. I am a professional writer from China Crafts Suppliers, which contains a great deal of information about led flashlights wholesale , gucci key chain, welcome to visit!
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