POWER SYSTEMS 2
ASSIGNMENT 1
QUESTION
Power systems are connected to loads of various sizes and characteristics. these loads can be
resistive, capacitive or inductive loads. using these 3 categories, describe all the typical loads
found in power system highlighting how they interact with power system and their impact on
the power system.
List and explain other categories of loads.
SOLUTION
Electrical Load
Any electrical device that consumes electrical energy
1. Resistive Load
Resistive load is defined as An electrical load that consumes electrical energy and converts it
into thermal or heat and light energy form .
Resistive load resists the flow of current through it due to its large resistance and hence
converts that Electrical energy into heat or light energy.
They have a power factor of 1 (unity), meaning the voltage and current are in phase.
Examples of Resistive load includes:
Incandescent bulb,
Electric heater,
Electric iron, and any electrical load that consists of only heating elements, etc.
Interaction Resistive Loads with the power system.
It consumes only Active power.
In pure Resistive load, current and voltage waveform becomes exactly in phase with
each other, hence the phase difference between voltage and current will be zero.
(Hence power factor of pure resistive load becomes unity )
Power flows from source to load.
Impact on the power system.
Resistive loads do not cause reactive power demand, which simplifies power system
operation and also increase the demand on generators and transmission lines since they
consume real power.
2. Inductive Loads
Inductive loads are electrical loads that consume only reactive power. they store energy in a
magnetic field and have a lagging power factor.
Inductive loads, like motors, transformers, and solenoids, have a magnetic field that
introduces reactive power into the system. This reactive power causes a lagging power factor,
reducing the system’s efficiency and leading to increased power losses.
Inductive loads can also generate harmonics, which can degrade power quality and damage
sensitive equipment.
3. Capacitive Loads
Capacitive loads store energy in an electric field and have a leading power factor.
Examples of capacitive loads
A battery in charging condition,
Buried cables,
a motor starter circuit, etc.
These loads have a leading power factor and can counteract the reactive power introduced
by inductive loads, improving overall system efficiency. However, capacitive loads can
also generate harmonics and cause voltage fluctuations if not properly managed.
4. Non-linear Loads
Non-linear loads, including electronic devices like computers, LED lights, and variable
frequency drives, draw current in a non-sinusoidal manner. These loads generate harmonics
that can cause voltage distortion, overheating, and premature equipment failure. Proper
harmonic mitigation techniques, such as filters and isolation transformers, are crucial for
managing the impact of non-linear loads.
5. Intermittent Loads
Intermittent loads, like air conditioners and refrigerators, switch on and off periodically,
causing sudden changes in power demand. These fluctuations can cause voltage dips, system
instability, and increased power losses. Effective load management strategies are essential to
minimize the impact of intermittent loads on power systems.
