Characteristic parameters of transformer

Rated Capacity
Refers to the output power of the transformer under operating conditions, expressed in apparent power. Represented by SN, the unit is KVA or VA. Rated voltage
Refers to the voltage value applied between the outlet terminals of a single-phase or three-phase transformer. Represented by UN, the unit is KV or V. The primary rated voltage is represented by UN1, and the secondary rated voltage is represented by UN2.

Rated current
It refers to the current passing through the outlet terminals of the primary and secondary windings of the transformer under the conditions of rated capacity and allowable temperature rise. It is represented by IN and the unit is KA or A. The primary winding current is represented by IN1, and the secondary winding current is represented by IUN21.

Rated frequency
The operating frequency specified in the batch transformer design. Expressed by ƒN, the unit is Hertz (HZ). Our country stipulates that the rated frequency is 50HZ. Load loss
No-load loss is also called iron loss. It refers to the active power absorbed by the transformer when the baby voltage at rated frequency is applied to the terminals of one side of the winding and the outlet of the other side of the winding is open circuit. It is represented by P0 and the unit is W or KW. No-load loss is mainly hysteresis loss and eddy current loss in the iron core. Its value is closely related to the iron core material and manufacturing process. It is generally believed that the no-load loss of a transformer will not change with the change of load size.

No-load current
When the secondary of the transformer is open circuit, there is still a certain current in the primary. This part of the current is called no-load current. No-load current consists of magnetizing current (generating magnetic flux) and iron loss current (caused by core losses). For a 50Hz power transformer, the no-load current is basically equal to the magnetizing current. Represented by I0. It is usually expressed as the percentage of the no-load current to the rated current, that is, I0 (%) = (I0/IN) × 100%. The larger the transformer capacity, the smaller the value.

load loss
Load loss is also called short-circuit loss and copper loss. It refers to the current flowing through the winding outlet terminal when the tap winding is connected to its main tap position and connected to the rated frequency voltage. The outlet terminal of the winding on the other side is short-circuited. When the rated current is the rated current, the active power consumed by the transformer is expressed in PK. The unit is W or KW. The size of the load loss depends on the material of the winding, etc. The size of the load loss during operation changes with the change of the load.

Transformation ratio
The ratio of the rated voltage of the high-voltage side to the rated voltage of the low-voltage side of the batch transformer, that is, UN1/UN2.

Insulation resistance
Indicates the insulation performance between the coils of the transformer and between each coil and the iron core. The level of insulation resistance is related to the performance of the insulating material used, temperature and humidity.

Impedance voltage (%)
Short-circuit the secondary winding of the transformer and slowly increase the voltage in the primary winding. When the short-circuit current of the secondary winding is equal to the rated value, the voltage applied to the primary side at this time is generally expressed as a percentage of the rated voltage.

Phase
Three-phase is represented by S at the beginning, and single-phase is represented by D at the beginning.

Association group label
According to the phase relationship between the primary and secondary windings of the transformer, the transformer windings are connected into various combinations, which are called connected groups of windings. In order to distinguish different connection groups, clock representation is often used, that is, the phasor of the high-voltage side line voltage is used as the long hand of the clock and is fixed at 12, and the phasor of the low-voltage side line voltage is used as the short hand of the clock. See where the short hand points. A number is used as the label of the connection group. For example, Dyn11 means that the primary winding is a (triangle) connection, the secondary winding is a (star) connection with a center point, and the group number is (11) point.