Types of Current and Domestic Electrification
According to the flow of charged particle in a circuit, there are two types of current.
- DC Current: In DC current the polarity of the current does not change. The flow of current is linear from the negative terminal to positive terminal. The voltage of direct current is normally the same and small. DC current can be changed to AC current by the use of an inverter.
- AC current: In AC current the polarity of the current changes according to its frequency. In Nepal, the distributed electricity has 50Hz of frequency that means the polarity of the current changes 50 times a second. AC current can be changed to dc current by the use of a rectifier.
Fuse is the special wire that melts when a certain amount of electricity flows through it. It happens due to heating effect (link to the heating effect) caused by electricity and we are going to talk about it later on. Fuses are made according to the maximum amount of current flowing into the circuit. If a circuit needs small amperage of current then we can use fuse with low amperage (in household normally 5 to 15A of fuse is used) and if the circuit needs high amount of current then high amperage of fuse is used (in small scale industries up to 30A of fuse is used and in heavy industries fuse use varies greatly). Fuse is made from a special alloy of tin and lead and the amount of lead and tin determines the capacity of the fuse. The small wire is enclosed in a glass case and sealed with small iron plates. But if we are using a fuse box then, the setting is different.
Selection of fuse:
To know what capacity of a fuse to use we have to find out how much of current is needed in the circuit. For that, we have to know the potential difference (V) of the circuit and total power drawn (P) by the appliances in that circuit. Using the formula, I = PV.We know the total current flowing in the circuit. Now if we use a fuse that has less amperage than the current flowing in the circuit the fuse cannot handle the flow of charged particles and breaks. So, we have to use the slightly higher capacity of fuse than that of current in our circuit.
Things to remember while wiring a home:
- A switch must be added the live wire. So that when the switch is off there is no electricity running through the wire.
- Fuse if added must be added to the live wire. Because if electrical appliances draw more current than needed fuse will go off and there won't be excessive current in the circuit.
- The capacity of fuse must be chosen appropriately to the current requirement. The normal household does not require much of electricity so smaller fuse can be installed but for small scale industries larger fuse than the household is needed and for large industries where heavy machinery are to be operated, a large capacity fuse is required.
- Each room or flat must have different fuse associated with them. If one fuse goes off then only that room's (flat) electricity is cut off rather than the entire house.
- The places where wires are laid and switches are placed must be prevented from water or moistness. Since water can conduct electricity we can get shocks and loss of electricity can happen.
- The line to the power socket and the bulbs must be separate. If there is a short circuit in the power socket, then also, we can light bulbs.
Coloration of Wire:
When we see a wire we actually see copper wire enclosed in a casing of different colors. Those casings are there to insulate the wire and we do not get a shock while touching it. The colors of the wire differ according to their type and country it is found. Normally in Nepal live wire has a red casing to it, neutral has black and earthing has a yellow color. But some might use brown colored wire for live wires, blue for neutral and green for earthing. The coloration is done because it is easier to know which wire is live or neutral or earthing.
- There are two types of current. They are AC current and DC current.
- In DC current the polarity of the current does not change.
- In AC current the polarity of the current changes according to its frequency.
- Fuse is the special wire that melts when certain amount of electricity flows through it, Fuses are made according to the maximum amount of current flowing into the circuit.
- To know what capacity of fuse to use we have to find out how much of current is needed in the circuit. For that we have to know the potential difference (V) of the circuit and total power drawn (P) by the appliances in that circuit.
- Each appliance in a room can be independently switched on or off.
- The same potential difference is applied across each appliance.
- If one line is overloaded or short circuited, the fuse in the whole circuit is blown off. The other distributed circuits are also affected.
- If the electric power is to be switched off in a room for repairing or for any other purposes, the electric power in whole circuit is blown off.
- Low melting point
- High resistance
Fuse should always be connected with a live line. When the fuse goes off, current is cut off and there is no chance of electric shock.
Fuse should be always connected to the live or phase wire so that if the fuse is broken due to the over current strength there won't be electrical accident as well as there won't flow the current to the equipment.
The earthing prevents the damage of the property, life and also prevents the electric leakage. It also saves the damage from the lighting.
- It is easy to identify the wire in the electrical work inside the ground.
- It is easy to identify the phase wire, neutral wire and earthing wire.
The polarity of the current does not change in ______.
both AC and DC
The polarity of the current changes according to its frequency in ______.
both AC and DC
The polarity of electricity provided in Nepal changes _______.
61 times second
50 times second
60 times second
51 times second
The special wire that melts when certain amount of electricity flows through it is ______.
Which color is used for all purpose?black
Which color indicate neutral?purple
Which color is used for the grounding of an electric circuit?red
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