AMerger parameters, may short-circuit parameters are

Transformer with an inductive load may simplify the phase diagram.
Under the simplified equivalent circuit, steady state occurs when the transformer short circuit = 0, short-circuit current is only by the parameters within the limits leakage reactance, that is. The current large, can reach 10 to 20 times rated current.
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This, we learned of the transformer (the motor is the same) in three ways: basic equations, equivalent circuit, phasor diagram.
Suitable for qualitative analysis of the basic equation; equivalentcircuit for the quantitative calculation; phase diagram for the phase relationship between the amount of size and phase analysis.
Example 1.2
1.5 Determination of transformer parameters
1.5.1 Load Test
No-load test, the secondary side open, one side applied voltage U1N, measuring U1, U20, I0, P0. Calculate transformation ratio k, excitation impedance Zm, excitation resistance Rm, and further calculation of excitation reactance Xm. For security purposes, usually in the low pressure side of the load test, and then converted to high-pressure side. Should be noted that the selected load test and measurement side must be the same rating.
Example: 1.3
1.5.2 Short Circuit Test
Short-circuit test, the secondary side open, one side of the low voltage applied to the primary current rating I1N, measuring Uk, Ik, Pk. Calculation of short circuit impedance Zk, short-circuit resistance Rk, further calculation short circuit reactance Xk.. In order to calculate accurately, usually in the high side for short circuit test. If you choose to select the low pressure side to low side when the rated current value, then the parameter converted to high pressure side.
Example 1.4
What value of 1.6 standard
What standard values: the actual value of a physical quantity with units of its selected base value (usually nominal) ratio as the value of the physical quantities of the standard Mody.
Basis: in the motor and transformer, the rating of the physical quantities used as the base value. Three-phase motors rated phase value is used  as the base value.
Representation: in the upper right corner of the physical symbol plus "*" number.
Voltage basis: What standard values:
Current base value: What standard values:
Resistance basis: What standard values:
What standard resistance values:,
What value of reactance scale:,
Note: (1) Find the standard What value, what side of the physical quantities on the use of which side of the base value, meaning that If converted to a secondary side, you should use one side of the rating as the base value.
      (2) in the three-phase transformer, the formula U1N, U2N, I1N, I2N, are relative values, rather than the line value.
Advantages:
What with the standard value of said performance data of various parameters and range of small, independent of the transformer capacity, facilitate the comparison of different transformer capacity. Such as: What standard load current range of 0.005 ~ 0.025; short-circuit impedance standard range from 0.04 Mody 0.105.
What use of standard value, the secondary side of the physical quantities do not need a translation. Because:
     
What use of standard value, the value of the physical quantities simplified, and all rating What value is a standard.
What short-circuit impedance Zk of the standard value is equal to the standard short-circuit impedance voltage uk What values, namely:
     ; Similarly there are,
Short-circuit impedance voltage uk = I1NZk, the resistance component ukr = I1NRk, reactance component ukx = I1NXk
From the perspective of running, hope uk smaller, the output voltage with load fluctuations smaller; but impedance voltage is too small, meaning that short-circuit impedance is small (equal to two standard Mody value), will inevitably result in short circuit current is too large, may damage to the transformer.
Example 1.5
1.7 Operating Characteristics of the transformer (voltage change rate and efficiency)
1.7.1 voltage change rate (also known as voltage regulation)
Definition: the transformer primary winding rated voltage, load power factor of a certain size and no-load and load, the secondary terminal voltage changes (U20-U2) and the secondary side of the ratio of the rated voltage U2N. Namely:
Short circuit parameters and load power factor angle to represent the derivation of the rate of voltage change:
According to the simplified equivalent circuit transformer, knowledge
Obtained phase diagram.
1.7.2 Efficiency
More efficient transformers, small and medium can reach 95% to 98%, large power transformers up to 99%.