# Important Electrical Hand Note For Interview (Part – 01)

This article is mainly a must-need hand note for every EEE engineer. I know you know everything on my list. But yet, you can have a collection of all these common terms of Electrical engineering. So I tried to make a hand note of important Electrical terms like current, voltage, resistance, etc. Continue reading; if you need, you can add these to your collection.

## Why You Need Electrical Hand Note

You will need all these common terms, including PGCB, DPDC, DESCO, REB, EGCB, and any government/private job’s written and VIVA examination. Especially in SAE (Electrical) job
preparation.

But it’s not only important for job preparation when you are an electrical engineer; these common things will be asked of you anywhere. Maybe in your office, your boss can question you about these. And then, if you can’t answer, maybe you will feel bad. So just not for any job preparation; as an engineer, be aware of these notes.

### What Is current?

To speak easily, when free electrons or ions run between conductive substances and the rate at which it flows in a certain direction, it calls current. It is expressed by “I.” When we measure current as Ampare, then we use A or Amp. Or coulomb/sec.

### What Is Voltage?

Free electrons of atoms of conductive matter that are a force or pressure to displace from an electrical circuit to a conductor are called potential difference or voltage. It is expressed by V.

### What Is Resistance?

Current flows through the conductive material. And while current flows through a conductor, it gets a barrier by the resistor and occurs a voltage drop; it calls Resistance. The symbol is R or r, and the Resistance unit is the ohm (Ω).

### What Is Transformer?

A transformer is an electrical machine that works as a voltage conversion. Transformar is a device that helps to flow current from one circuit to another circuit following the electromagnetic induction rule and works to level up or down of working voltage.

There are two types of transformer: (a) Step Up Transformer & (b) Step Down Transformer. The transformer works following the magnetic induction principle. There is no rolling part or rotor in Transformer; it’s a completely stationary device. The transformer has two windings: Primary and
Secondary winding.

After supply voltage, the Primary winding creates a magnetic field in the middle of the magnetic flux iron core with a secondary winding, creating a Magnetic field. As a result that increased Voltage is found in the secondary coil.

The rate of voltage change of the transformer depends on the coil of the primary winding. But remember, the transformer only causes a voltage change. But power and frequency remain unchanged. The power doesn’t change but changes the voltage, so the amount of current also changes.

There are two types of instrument transformers:

CT (Current Transformer): It is usually used to measure current.
PT (Potential Transformer) It is usually used to measure voltage.

### Transformation Ratio

Induced on both sides of the transformer depends on coil turns, coil patches, voltage, and current. To explain easily, we can say the ratio of the primary and secondary winding is the transformation or transformer turn ratio.

This is usually expressed by a= Ep / Es = Np / Ns = Is / Ip

### What Is Circuit Breaker?

A circuit breaker is an electrical switching device between the supply and the electrical circuit. If an accident happens, the circuit breaker disconnects the circuit from the supply line. However, it is an electrical device that works as a controller and protection device in the circuit.

Circuit Breaker automatically disconnects electrical circuits from the supply in case of overload or short circuit. The breaker does not connect to the circuit automatically; we do it manually later after repairing the issue.

### What Is Isolator?

Isolators are a piece of special equipment or mechanical device for electrical substations used between input and output to disconnect the circuit. It works like a circuit breaker. But the difference is isolator use with a transformer in no-load conditions or disconnecting from the line under slight load conditions. The isolator is a kind of switch which works offline.