The role of current transformers - measurement? protection?

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

LC03-3.3 SOP8 TVS Static Protection 3.3V

GW MB10F 0.8A 1000V rectifier bridge

Introduction: Current transformers , as the name implies, are instruments that affect each other on both sides. Then the problem comes. What is the role of current transformers ? Measurement? Protection? Let's take a look at it~~

First, the role of current transformers - - Introduction

The current transformer, the English name is Current transformer, and the symbol is TA. It is an instrument that converts a large current into a secondary small current by a closed core and winding according to the principle of electromagnetic induction. The structure is as shown in the figure below. The number of turns in the primary winding is small, the string is in the circuit that needs to measure the current, and the number of turns in the secondary winding is large. The string is in the measuring instrument or the protection circuit. When it is in working state, the current mutual inductance The secondary circuit of the device is closed (otherwise, there is a safety hazard), and the impedance of the measuring instrument or the protective circuit series coil is small, so that its working state is close to the short circuit.

Second, the role of current transformers - - for measurement

One of the roles of current transformers is for measurement, often used to bill or measure the current level of a device in operation. In the measurement of large alternating current, in order to facilitate the measurement of the instrument and reduce the risk of directly measuring the high voltage, it is often necessary to use a current transformer to convert it into a more uniform current, where the current transformer starts. The role of converter and electrical isolation. The current transformer converts the high current into a low current proportionally according to requirements. For the measurement, the primary side of the current transformer is connected to the primary system, and the secondary side is connected to the measuring instrument or the relay protection device.

Third, the role of current transformers two - for protection

The second function of the current transformer is for protection, often used in conjunction with the relay device. When the line is short-circuited or overloaded, the current transformer sends a signal to the relay device to cut off the fault circuit, thereby achieving protection power supply. The purpose of system security. The protection current transformer is different from the current transformer for measurement, and it can work effectively only when the current is several times or several times larger than the normal current, and it requires reliable insulation and sufficient accuracy limit. Coefficient, sufficient thermal stability and dynamic stability.

Fourth, the role of current transformers - - matters needing attention

1. During the operation of the current transformer, the secondary side is not allowed to open, and it must be kept closed. Because once the secondary side is opened, the magnetic flux and secondary voltage will far exceed the normal value (up to thousands or even tens of thousands of volts), which is extremely harmful to the safety of operators and equipment.

2. The wiring mode of the current transformer should follow the series principle, that is, the primary winding is connected in series with the circuit under test, and the secondary winding is connected in series with the measuring instrument or relay device.

The role of current transformer