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1) Difference between DC power and AC power

There are two types of electricity: direct current and alternating current. There are two methods of electric current. These are direct current (DC) and alternating current (AC).

Direct current is a method in which electricity always flows in a certain direction, as compared to the flow of a river. It refers to the flow of electricity obtained from batteries, batteries, solar cells, etc.

On the other hand, alternating current (AC) is a method in which the positive and negative sides are constantly switched periodically and the direction of the flow of electricity changes accordingly. This is the flow of electricity obtained from a generator or outlet. The electricity produced at power plants and sent to homes is also transmitted as alternating current.

The diagram below shows the flow of DC and AC electricity. The direction of the current of the voltage is always constant. The direction of the current is always switched periodically, and the voltage is also switched. In direct current, the voltage is always constant, and the electricity flows in a certain direction. In contrast, in alternating current, the voltage periodically changes from positive to negative and from negative to positive, and the direction of the current also periodically changes accordingly. In direct current, the voltage is always constant, and the electricity flows in a certain direction. In contrast, in alternating current, the voltage periodically changes from positive to negative and from negative to positive, and the direction of the current also periodically changes accordingly.

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2)Circuit Breaker Difference MCB, MCCB, RCCB, ELCB

What is MCB 2pol / 3pol / 4pol MCB is available in 16Amp, 32Amp, 64Amp. Fans, Cooler, Lights, TV, Laptop, Mobile Charger, etc., work on normal load 16Amp. 32Amp MCB is used for Air Conditioner, Water Pump, Heater, Geyser, etc. And 64Amp MCB for Industrial and Commercial purposes.

What is MCB

MCB stands for Miniature Circuit Breaker. It automatically switches OFF electrical circuit during any abnormal condition in the electrical network such as overload & short circuit conditions. However, fuse may sense these conditions but it has to be replaced though MCB can be reset. The MCB is an electromechanical device which guards the electric wires &electrical load from overcurrent so as to avoid any kind of fire or electrical hazards. Handling MCB is quite safer and it quickly restores the supply.When it comes to house applications, MCB is the most preferred choice for overload and short circuit protection. MCB can be reset very fast & don’t have any maintenance cost. MCB works on bi-metal respective principle which provides protection against overload current&solenoidshort circuit current

What is MCCB

MCCB stands for Molded Case Circuit Breaker. It is another type of electrical protection device which is used when load current exceeds the limit of a miniature circuit breaker. The MCCB provides protection against overload, short circuit faults and is also used for switching the circuits. It can be used for higher current rating and fault level even in domestic applications. The wide current ratings and high breaking capacity in MCCB find their use in industrial applications. MCCB can be used for protection of capacitor bank, generator protection and main electric feeder distribution. It offers adequate protection whenever an application requires discrimination, adjustable overload setting or earth fault protection.

What is RCCB

RCCB stands for Residual Current Circuit Breaker. This residual current device is basically an electrical wiring device that disconnects the circuit whenever there is leakage of current flow through the Human body or the current is not balanced between the phaseconductor. It is the safest device to detect and trip against electrical leakage currents, thus ensure protection against electric shock caused by direct contacts. RCCB is generally used in series with an MCB which protects them from over current and short circuit current. Both phase and neutral wires are connected through a RCCB device. These are an extremely effective form of shock protection&widely used for protection from a leakage current of 30,100 & 300mA. It is essential lifesaving equipment used to protect the human body from electrical and is mandatory in many states for domestic installation.

What is an Earth Leakage Circuit Breaker (ELCB)

An ECLB is one kind of safety device used for installing an electrical device with high earth impedance to avoid shock. These devices identify small stray voltages of the electrical device on the metal enclosures and intrude the circuit if a dangerous voltage is identified. The main purpose of the Earth leakage circuit breaker (ECLB) is to stop damage to humans & animals due to electric shock. An ELCB is a specific type of latching relay that has a structure’s incoming mains power associated through its switching contacts so that the circuit breaker detaches the power in an unsafe condition. The ELCB notices fault currents of human or animal to the earth wire in the connection it guards. If ample voltage seems across the ELCB’s sense coil, it will turn off the power, and remain off until manually rearrange. A voltage sensing ELCB doesn’t detect fault currents from human or animal to the earth.

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3) MCB different types of B/ C / D / K / Z

Types of MCB based on Tripping Characteristics. Difference between Class A, B, C, D, K and Z Type Miniature Circuit Breakers (MCB) MCBs are classified into different types based on their tripping characteristics which are the range of tripping fault current at which the device operates in the event of a short circuit or overload

Type Tripping Current Operating Time

Type B 3 To 5 times the full load current 0.04 To 13 Sec

Type C 5 To 10 times the full load current 0.04 To 5 Sec

Type D 10 To 20 times the full load current 0.04 To 3 Sec

Type K 8 To 12 times the full load current <0.1 Sec

Type Z 2 To 3 times the full load current <0.1 Sec

Type A, K, and Z MCBs have extremely small operating times compared to type B, C, and D MCBs. Class A, K, and Z are highly sensitive breakers that operate very quickly in a short time used to protect sensitive devices.

4) Difference between MCB / MCCB / RCCB / ELCB

Difference between MCB and MCCB

MCB-MCCB

1 It stands for Miniature Circuit Breaker. It stands for Molded Case Circuit Breaker.

2 Rated current not more than 125 Ampere. Rated Current up to 1600A

3 Its interrupting current rating is under 10KA Their interrupting current ranges from around 10KA -85KA

4 Judging from their power capacities, MCB is mainly used for low Breaking capacity requirement mainly domestic. MCCB is mainly used for both low and high Breaking capacity requirements mainly industrial.

5 Its trip characteristics are normally not adjustable since they basically cater to low circuits. Its trip current may be fixed as well as adjustable for overload and magnetic setting.

Difference between RCCB and ELCB

RCCB-ELCB

1. RCCB refers to ear stands for Residual Current Circuit Breaker. ELCB stands for Electric Leakage Circuit Breaker.

2. It is a new name and refers to current operated devices. ELCB refers to voltage operated earth leakage device.

3 It ensures 100% detection of leakage current& is available to sense the AC as well as DC leakage current. It is not preferable as it can only detect current that flow back through the main earth wire.

4 RCCB has no connection with the earth wire and that’s why it can trip when both currents (phase and neutral) are different and it withstands up to both the currents are same. ELCB is working based on Earth leakage current. These devices measured the voltage on the earth conductor; if this voltage was not zero this indicated a current leakage to earth.

5) isolation switch What does an isolation switch do

An isolation switch acts as a circuit breaker on your mains electrical supply so that any electrical work (such as an EV charger or solar installation) that is going to take place within a property can be completed safely by a private electrician or anyone doing electrical work on your home.

When the switch is turned off, there would be no power after the isolation switch, which in turn would allow a private electrician to safely complete any maintenance work or repairs on the member's internal electrical set-up. Isolators are offered in Single Pole, Double Pole, Three Pole & Four Pole Variants in various current ratings such as 25A, 40A, 63A, 80A, 100A and 125A.

6) What is an Electrical Contactor

A contactor is an electromechanical control device that used to make or break the connection between the load and power supply. The use of a contactor is similar to the relay. But the device used for higher current carrying application is known as a contactor and the device used for lower current applications is known as Relay.

A contactor has several contacts as per the application and load. Generally, these contacts are normally open (NO) contact. And hence the load is shut off when the coil of the contactor is de-energized. But the contactor can design for both normally open and normally close applications. The most common application of contactor is in the starter that used to turn ON and OFF the equipment like motor, transformer, etc.

A contactor is an electrically controlled switch used for switching a power circuit, similar to a relay except with higher current ratings. A contactor is controlled by a circuit which has a much lower power level than the switched circuit. Contactors are oftenly used for 150 Hp motor.

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7) SPD Surge Protective Devices are

Surge Protective Devices are designed to protect against transient surge conditions. Large single surge events, such as lightning, can reach hundreds of thousands of volts and can cause immediate or intermittent equipment failure. However, lightning and utility power anomalies only account for 20% of transient surges. The remaining 80% of surge activity is produced internally. Although these surges may be smaller in magnitude, they occur more frequently and with continuous exposure can degrade sensitive electronic equipment within the facility.

Principle SPD is designed to limit transient overvoltages of atmospheric origin and divert current waves to earth, so as to limit the amplitude of this overvoltage to a value that is not hazardous for the electrical installation and electric switchgear and controlgear.

SPD eliminates overvoltages

in common mode, between phase and neutral or earth; in differential mode, between phase and neutral. In the event of an overvoltage exceeding the operating threshold, the SPD conducts the energy to earth, in common mode; distributes the energy to the other live conductors, in differential mode.

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8) Determine cable size of the Calculate load current

cable size Calculate load current

kW	Amps	Cable Size (AL)	Cable Size (Cu)
2.2-Kw	3.83	4.Sq-mm	2.5-mm
5.5-Kw	9.56	10.Sq-mm	2.5-mm
9.3-Kw	16.17	10.Sq-mm	4-mm
18.5Kw	32.17	35.Sq-mm	10-mm
30-Kw	52.17	70.Sq-mm	35-mm
75-Kw	130.43	150.Sq-mm	70-mm
150.Kw	260.86	400-mm	150-mm

cable size of the 3phece moter

Moter-HP	kW	Amps	Cable Size
2-Hp	1.5-Kw	2.61-A	2.5-mm
5-Hp	3.7-kw	6.43-A	6-mm
10-Hp	7.5-Kw	13.5-A	10-mm
15Hp	11-Kw	19.13-A	16-mm
20-Hp	15-Kw	26.09-A	25-mm
30-Hp	22-Kw	38.26-A	50-mm
60-Hp	45-Kw	78.26-A	70.Sq-mm

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9)ELECTRICAL EARTHING

Earthing is defined as “the process in which the instantaneous discharge of the electrical energy takes place by transferring charges directly to the earth through low resistance wire.” Low resistance earthing wire is chosen to provide the least resistance path for leakage of fault current.

Types of Earthing:

1. Copper Plate Earthing / Copper Pipe Earthing

2. Gi Plate Earthing / Gi Pipe Earthing

3. Electrode Chemical Earthing

Importance of Earthing

The earthing is essential because of the following reasons • The earthing protects the personnel from the shortcircuit current. • The earthing provides the easiest path to the flow of shortcircuit current even after the failure of the insulation. • The earthing protects the apparatus and personnel from the high voltage surges and lightning discharge.

Have you ever experienced a mild shock when you touch certain appliances while in operating condition? Sometimes these shocks can be dangerous and can lead to major hazards. To avoid mishappenings, it is always advisable to have a proper earthing done to the building. This process of sharing the charges with the earth is called earthing. Earthing is a simple way for the leakage of current and hence protects the devices from electrical damage. Grounding is also a safety process that protects the entire power system from malfunctioning and is mainly used to balance the load when the electric system overloads.

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10)Amps to kW Conversion Formulas

Amper / watts / K Watts / KWH / KVA (Unit )

(voltage / Sengel P 220/255 V – 3phase 480) *(current amp)

1000A=1W-1000W=1kw-1kwh=1 unit

Current amp X voltage = K Watts /

220V*16A=3.520 (3-Kw) = kvh = (Kilovolt Hour) 3 unit

(A x V = W x 1000 = 1 kw )

9A x 240V = 2160 W x 1000 = 2 kw =one hover =2 unit

Electrical terms

Are you a little puzzled by all the unit measurements on your bill? Here's a rundown of what they mean and how they apply to you. Volt (V) = a unit of electrical voltage A volt is the electrical force required to push current through an electrical circuit. Most businesses are supplied at a nominal voltage of 400V (three phase), which is frequently referred to as 'Low Voltage'. Kilovolt (kV) = 1000 volts This term is normally used for medium and high voltage business customers. Amp (A) = a unit of electric current An amp is the measurement of current flowing in an electrical circuit. Kilovolt-Amps (kVA) = 1000 volt-amps This is a term used to describe the level of 'apparent' power imported or consumed by your business, It is the basis of your Maximum Import Capacity (MIC) contract with NIE Networks. Watt (W) A watt is the unit of measurement of 'active/real' power.

For example, 1 volt passing a current of 1 amp through a basic circuit means your business uses 1 watt of electric power. Kilowatt (kW) = 1000 watts (W) A kW is the term used for 'active/real' electric power, it’s also known as 'Demand' or 'Load'. Megawatt (MW) = 1000 kilowatts (kW) A megawatt is sometimes used as a unit of measurement for large electric loads provided to business customers. Kilowatt hour (kWh) = 1000 watts for 1 hour 1 kWh is the amount of energy consumed by an electrical device (e.g. an electric heater) rated at 1kW (1000 watts) for 1 hour. On your Bill, you will see each 1 kWh used by your business as 1 unit.

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