A current transformer (CT) is a kind of instrument transformer that is used with several measuring devices. In those protective devices, the subordinate current remains proportional to the main current and approximately differs by a zero angle.
Functions of CT:
Current transformers are used for different functions such as –
• It supplies the protecting relays with currents, whose magnitude remain proportional to the magnitude of the power circuit. Though there is a significant reduction in magnitude.
• The protective devices offered by the current transformer manufacturers cannot have a direct connection with the supplies of high magnitude. This is why current transformers supply current to those devices whose magnitude is proportional to their power.
• A CT is responsible to isolate high voltage circuits and the protective instruments.
Principle of working:
Well, the basic principle of working for a CT is similar to a power transformer (PT). Like a PT, the CT contains two windings – primary and secondary. Every time an alternating current (AC) flows into the primary winding, it generates an alternating magnetic flux, which in turn encourages AC into the secondary winding.
In the case of CT, the burden or load impedance is negligible. This is why the CT needs to operate in short circuit conditions. On the other hand, the secondary winding do not have a need to depend on the burden, rather they depend on the flow of current in the primary winding.
Types of Current Transformer:
The current transformer exporters provide multiple types of current transformer goods to many parts of the country and abroad. Depending upon the functions of CTs, they can be classified as –
1. Measuring current transformers – These are used to measure power, energy, and current. They are used with other measuring devices.
2. Protective current transformers – These are used with other protection equipment including relays, trip coils, etc.
Depending upon the function construction of CT, they can be classified as –
1. Bar type – the integral part of the current transformer contains a bar of appropriate material and size.
2. Wound type – instead of having a full turn wound around the core, the current transformer contains an ore primary winding.
3. Window type – current transformer contains no primary winding. Its secondary wind is placed surrounding the current flowing conductor. The current flowing creates magnetic electric field via the conductor that encourages current flow through the secondary winding.
Advantages of current transformers:
1. It can measure very large current
2. Readings are not dependent on inductance, resistance, or capacitance value of the CT. It is to be noted that the main and subordinate windings of a CT are not made of pure inductive coils, still, they have the three parameters – C, L, and R.
3. The ammeter remains connected within the secondary winding and thus the measuring current is not associated with the power circuit, which is crucial for any high voltage system.
4. One CT is enough to operate multiple measuring instruments
5. CT can successfully measure the amount of power consumption in the circuit. In the operations of multiple relays, CT can be used in the power system.
The manufacturers produce current transformer products by maintaining all the quality standards and using state-of-the-art technology for manufacturing quality products in the industry.