Transformer: A transformer is a device that converts AC voltage, current and impedance. When alternating current passes through the primary coil, it generates alternating magnetic flux in the iron core (or magnetic core), which is the voltage (or current) induced in the secondary coil. To change the voltage level, load a large current.
1. Various transformers are divided into several categories according to cooling mode, moisture-proof mode, core or coil structure, power supply phase and purpose;
2. The transformer capacity is from small to large, from tens of volts to tens of MVA;
3. The primary side voltage of the transformer is greatly affected by the secondary load, and the system voltage is affected when the secondary load is large; 4. The secondary side load of the transformer is a variety of electrical equipment, which passes a large current and has a strong load capacity;
5. No matter how high the voltage at the primary side of the transformer is, the secondary voltage can be increased or decreased as required; 6. The shape and volume of transformers vary with capacity;
7. Transformers are often used in various situations.
The working principle of voltage transformer is the same as that of general transformer, but it is different in structure, materials used, capacity, error range, etc.
Voltage transformer: voltage transformer is a voltage conversion device that converts high voltage to low voltage to reflect the change of high voltage value with low voltage value. Therefore, voltage measurement can be directly carried out by ordinary ammeter through voltage transformer. 1. Voltage transformer, also known as transformer, is an electrical converter;
2. The capacity of voltage transformer is very small, usually only tens to hundreds of volts;
3. The voltage at the primary side of the voltage transformer is the grid voltage, which is not affected by the secondary load. In most cases, its load is constant;
4. The secondary side load is mainly the instrument and relay coil. Their impedance is very high and the current passing through them is very small. If the secondary load increases infinitely, the secondary voltage will decrease, resulting in an increase in measurement error.
5. The voltage transformer is used to measure the voltage indirectly, which can accurately reflect the value of the high voltage side and ensure the measurement accuracy;
6. Whether the primary voltage of voltage transformer is high or not, its secondary rated voltage is generally 100V, which makes the manufacturing of measuring instruments and relay voltage coils standardized. It also ensures the safety of instrument measurement and relay protection, and solves the insulation and manufacturing process problems of high-voltage measurement;
7. Voltage transformer is often used in the circuit of distribution meter measurement and relay protection.