Siemens APT current transformer - how to choose a current transformer?

Create Date: 2024-8-30 12:03:23|Source: APT/Siemens Shanghai Ergong

First, the principle of primary parameter selection of current transformer

The rated primary current of the current transformer is determined by the actual load of the tested circuit, and the rated primary current of the current transformer should not be less than the rated primary current of the circuit, and the rated current of the transformer is generally determined by multiplying the load current by the coefficient of 1.2-1.25. In addition, the rated continuous thermal current, rated short-time thermal current and rated dynamic and stable current of the current transformer should be able to meet the requirements of the maximum load current and short-circuit current of the primary circuit, and the development of the system should be considered.

Second, the principle of secondary parameter selection of current transformer

The rated secondary load of the transformer is the key parameter to determine the accuracy level, size and cost of the transformer, which should be reasonably selected according to the actual situation of the project. The rated secondary current of the current transformer is generally 1A, if it is conducive to the production or expansion of the transformer, and in some cases, in order to reduce the secondary open circuit voltage of the current transformer, the rated secondary current can also be 5A.

The rated output value should be selected in accordance with the following principles:

1. The rated output values of the measurement, P, and PR grades are expressed in volt-ampere. When the rated secondary current is 1A, the rated output standard value should be 0.5V · A, 1V · A, 1.5V · A, 2. 5v·a、5v·a、7. 5v·a、10v·a、15v·a。 When the rated secondary current is 5A, the rated output standard value should be 2. 5v·a、5v·a、10v·a、15v·a、20v·a、25v·a、30v·a、40v·a、50v·a；

2. What is the rated resistive load value of TPX, TPY and TPZ current transformers? Denote. The standard value of rated resistive load should be 0.5, 1, 2, 5, 7.5, 10;

The rated output value of the current transformer should be selected according to the rated secondary current value of the transformer and the actual load. In order to meet the requirements of transient characteristics, a larger rated output value can also be used.

Siemens APT current transformer - how to choose a current transformer?

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