Chapter 4: Electrical Parts; Section I Basic Knowledge - ZONGSHEN ZS125-86 Service Manual

In order to understand the structure and working principles of the electrical system of the motorcycle,
we must first have a basic knowledge of some electricity concepts.
1. Electricity, Current, Voltage and Resistance
The essential component of any substance is an atom, where there are positively charged nucleuses
and negatively charged electrons, both of which maintain a balance in the amount of charge. The positive
offsets the negative, so that the atoms are non-charged neutral. Once the object is affected by external
factors, such as friction, magnetic field, etc., this balance will be broken, so that electrons transfer. At this
time, the object is charged because atoms are no longer neutral. The nature of the charge carried by the
object is relevant to the increase or decrease in the number of electrons. When the electrons increase, the
object is negatively charged; when the electrons decrease, the object is positively charged.
Charges regularly move in a conductor in a certain direction, known as the current. Usually, the amount
of charge in a unit interval is used to measure the current intensity, expressed by I. The current intensity
is in amperes, expressed by A. Generally, the current flows from the positive pole to the negative pole of a
battery.
As there is interaction force among charges, it is necessary to apply work to overcome this force for
purpose of making charges to move. When moving positive charges, the work applied to overcome the
attraction among charges is called the potential. The difference in potential between any two points is
called the voltage, denoted by U. The voltage is in volts, expressed by V (v).
When the current flows in the object, the object will produce some resistance to it. This resistance is
called the electronic resistance, denoted by R. The resistance is Ohms, expressed by Ω.
Different materials have different resistances. For example, copper, iron, aluminum and other
metal have smaller resistances, known as conductors; wood, ceramics, plastic and other have greater
resistances, known as insulators; some objects are neutral in electrical conductivity (such as silicon ),
known as the semiconductors.
2. Ohm's Law
The Ohm's Law reflects the correlation among the voltage, resistance and current, that is, the current
I is in direct proportion to voltage U and the resistance R is inversely proportional to both of them. The
formula is: I=U/R, the formula can be changed to: U=IR, R=U/I.
3. Electrical Equipment, Direct Current and Alternating Current, Power Supply
The so-called electrical equipment, which is commonly referred to as the load, means the equipment
able to consume electricity and converts electricity into other forms of energy.
The device that provides the required electrical energy for the electrical equipment is called a power
supply, also called a power unit. The power supply provides the current for the electrical equipment in two
forms: direct current, whose scale and direction do not change over time; and alternating current, whose
scale and direction periodically change over time.
4. Circuit, Series Circuit and Parallel Circuit
A closed loop consisting of a power supply, electrical equipment, and a connecting wire is called a
circuit. The circuit has two basic forms: a series circuit and a parallel circuit. In a series circuit, several
electrical devices are connected to each other end-to-end without forks between. Then the currents
passing through each electrical device are identical. In a parallel circuit, two ends of each electrical device
are connected to the same two points, and the voltages at two ends are equal. In more complex motorcycle
circuits, series circuits and parallel circuits tend to exist at the same time.
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Chapter 4: Electrical Parts

Section I Basic Knowledge