Current Transformer (CT) is an instrument transformer in panel board. According to Electromagnetic induction, high current througth the CT's window (Primary Current) can induct and provide 5A / 1A (Secondary Current) on CT's connector for measurement.

The function of voltage transformer is used to transfer the input voltage into output voltage according to Faraday's Law of Electromagnetic Induction.  Whereas the function of Current transformer is used to transfer the big value current into small current for measuring..

Toroidal Transformer is a ring-shaped transformer which designed for higher power effifiency, lower electromagnetic interrupt and smaller size.

A magnetic contactor is an electromagnetic switch used primarily for remotely controlling motors, heaters, lighting systems and other high-power loads. The key functions include:Remote Control: By Using an electromagnetic coil to open and close the main contacts. High-Capacity Switching: Compared to push buttons and selector switched, contactors can handle high current and voltage loads efficiently. Protective Features: Working with overload relays or circuit breakers to prevent equipment damage from overloads or short circuits.

SMPS (Switch mode power supply) Transformer is a transformer specifically designed for high-frequency power or signals (from 10KHZ to 500KHZ, and more). They are commonly used as switch-mode power supplies, radio-frequency (RF) circuits, wireless communication devices, and more.

 A choke is an inductor primarily used to restrict alternating current (AC) flow while allowing direct current (DC) to pass smoothly. It is commonly used in power supplies and signal processing. 
The key applications include: 
1. Electromagnetic Interference (EMI) Suppression and Noise Filtering
2. Power Supply Filtering
3. Inrush Current Limiting
4. Common Mode and Differential Mode Filtering
5. RF (Radio Frequency) and Communication Applications