How To Select Batteries for Any Application

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The selection of batteries for any application is a critical exercise. A number of factors must be considered in selecting the best battery for a particular application. The characteristics of each available battery must be weighed against the equipment requirements and one selected that best satisfy these needs. The considerations that are important and influence the selection of the battery are tabulated below

Resistance and Reactance per km of Copper and Aluminium cables

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For the purpose of calculating voltage drop within a cable, the table below gives the reactance and resistance values for Copper and Aluminium cables:

Values for Copper Cables

Cable Size, S (mm2)	Single - Core Cable		Two - Core/Three Core Cables
	R(Ω/km) @ 80°C	X (Ω/km) @ 80°C	R(Ω/km) @ 80°C	X(Ω/km) @ 80°C
1.5	14.8	0.168	15.1	0.118
2.5	8.91	0.156	9.08	0.109
4	5.57	0.143	5.68	0.101
6	3.71	0.135	3.78	0.0955
10	2.24	0.119	2.27	0.0861
16	1.41	0.112	1.43	0.0817
25	0.889	0.106	0.907	0.0813
35	0.641	0.101	0.654	0.0783
50	0.473	0.101	0.483	0.0779
70	0.328	0.0965	0.334	0.0751
95	0.326	0.0975	0.241	0.0762
120	0.188	0.0939	0.191	0.074
150	0.153	0.0928	0.157	0.0745
185	0.123	0.0908	0.125	0.0742
240	0.0943	0.0902	0.0966	0.0752
300	0.0761	0.0895	0.078	0.075

Values for

How to Determine Voltage Drop in an Electrical Conductor

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Owing to the effect of voltage drop on electrical equipment, determination of the voltage drop of an electrical conductor is very important in helping to predict voltage drop level and ensure that it is in line with the relevant standard.
For an electrical conductor with impedance Z, the voltage drop is calculated by the following formula:

Where:
K   =     a coefficient equal to 2 for single phase and two phase systems.
             SQRT(3) for three phase systems
IB   =     load current in Amps. if no information are available, the cable carrying   
             Capacity of the conductor shall be considered.
L    =     Length of conductor in Km
n     =     is the number of conductors in parallel per phase
R    =     is the resistance of the single cable per kilometre in (Ω/km)
X    =     is the reactance of the single cable per kilometre in (Ω/km)

CosФ = power factor of the load

Resistance and reactance values

How Voltage Drop Affect Electrical Equipment and Installations

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In an electrical installation, determination of voltage drop from the point of supply to the load is very important. Excessive voltage drop on the supply line impacts most electrical equipment but not to the same degree. The effect of voltage drop on some key electrical equipment is given below.

Effects of Voltage Drop
Electric Motors
In an electric motor, the torque is proportional to the square of the supply voltage. Therefore, if the voltage drops the starting torque will also decrease, making it more difficult to start up motors. The maximum torque will also decrease .

Incandescent Lamps
The more the voltage drops the weaker the beam becomes and the light takes on a reddish tone.

Discharge Lamps
In general, they are not very sensitive to small variations in voltage, but in certain cases, great variation may cause them to switch off.

Electronic Appliances
They are very sensitive to

How a Residual Current Device (RCD) Works

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RCD means Residual Current Device. They are so called because they work based on the residual current in a circuit. The RCD is an electrical safety device specifically designed to immediately switch the electrical current flow when current "leaking" to earth is detected at a level harmful to a person using electrical equipment. An RCD offers a high level of personal protection from electric shock.

RCDs also help to reduce the risk of fire by detecting electrical leakage to earth in electrical wiring and accessories. RCDs are designed to operate within 10 to 50 milliseconds and to disconnect the electricity supply when they sense harmful leakage, typically 30mA

RCD Operating Principle

In absence of an earth fault,