Skip to content
Electricalterminology

Electricalterminology

Best Blog for Basic Electrical Knowledge

Primary Menu
  • Electric
  • Manufacturers & Brands
  • Electronics
  • About Us
  • Contact
  • Affiliate Disclosure
  • Home
  • Electric
  • Short Circuit vs Overload: Understanding the Differences
  • Electric

Short Circuit vs Overload: Understanding the Differences

electricalterminology 2 years ago
Short circuit vs overload

Electrical networks and machines are subject to various types of faults while in operation. Short circuit and overload are the most dangerous faults in the power system. They change the circuit structure, causing changes in power distribution, which will bring energy loss, and damage to the stability of the power system, affecting the normal operation of electrical equipment. Despite their similarities, these two phenomena are different from each other.

Differences Between Short Circuit and Overload

The differences between electrical short circuit and overload are the following:

1. Definitions

The main difference between short circuit and overload is the definition. An overload is a condition at which an electrical load draws a current above its rated value, for a prolonged period. A short circuit is an accidental or intentional conductive path between two or more conductive parts forcing the electric potential differences between these conductive parts to be equal or close to zero.

Other definitions of short circuit:

  • An unwanted low-resistance connection between two points in an electric circuit.
  • An abnormal electric path.
  • The condition occurs when a circuit path is created between the positive and negative poles of a battery, power supply, or circuit.
  • A situation occurs when hot and neutral wires come in contact with each other.
  • An accidentally established connection between two points in an electric circuit, such as when a tree limb or an animal bridges the gap between two conductors.
Short circuit

Other definition of overload:

  • Electrical overload is a type of overcurrent where more amperage is put across an electrical wire or circuit than it can handle leading to excessive generation of heat, and the risk of fire or damage to equipment.
overload

2. Voltage levels

A short circuit has zero voltage across it for any finite current flow through it. On a circuit diagram, a short circuit is designated by an ideal conducting wire with zero resistance. In an overload, the voltage can be low, but cannot be zero.

3. Current levels

The maximum value of the short circuit current is directly related to the size and capacity of the power source and is independent of the load current of the circuit protected by the protective device. The larger the capacity of the power source, the greater the short circuit current will be. Overload current is directly related to the capacity of the electrical load. That’s why the current level of the short circuit is much higher than the overload current. The short circuit is multiple of the rated current. Overload is close to the rated current.

4. Danger levels

A short circuit is more dangerous than an overload. Because the current level is higher. A short circuit is extremely dangerous in high-voltage applications. A short circuit has fast energy transfer but an overload has slow energy transfer.

5. Causes

Electric power systems are designed to be as free of short circuits and overloads as possible through careful system and equipment design, as well as proper installation and maintenance. However, even with these precautions, short circuits and overloads do occur.

Some causes of short circuits are:

  • Presence of vermin rodents in the equipment.
  • Loose connections.
  • Voltage surges.
  • Deterioration of insulation.
  • Accumulation of moisture, dust, concrete juice, and contaminants.
  • The intrusion of metallic or conducting objects such as fish tape, tools, jackhammers, or payloaders.

Some causes of overloads are:

  • Excessive consumer loads.
  • Faulty appliances.
  • Bad wiring and grounding.
  • Improper use.

6. Protection devices

Short circuit and overload must be quickly removed from the power system and this is the job of the circuit protective devices. To accomplish this, the protective device must have the ability to interrupt the maximum current that can flow at the device location.

Fuses and circuit breakers can protect systems against overload and short circuits. Thermal overload relays only protect against the overload. Magnetic only breakers only protect against only short circuits.

7. Consequences

When a short circuit occurs on a power system, several things happen – all of them are bad:

  • At the short circuit location, arcing and burning can occur.
  • Short circuit current flows from various sources to the short circuit location.
  • All components carrying short circuit currents are subject to thermal and mechanical stress.
  • System voltage drops in proportion to the magnitude of the short-circuit current.

The consequences of overload are:

  • Increase of the electrical energy consumption due to residual current caused by isolation issues in the wiring.
  • Personal accident by direct contact with damaged wires.
  • Sustained overload can result in a short circuit.

8. Calculations

The calculation of short circuit currents is essential to the selection of adequately rated protective devices and equipment in industrial and commercial power systems. Today, power systems carry larger blocks of power and have greater safety and reliability requirements. There are lots of parameters that should be considered when calculating short circuits. For this reason, the calculation of short circuits is not easy and must be done carefully.

9. The reaction of protection devices

The reaction of the protection devices against short circuits is extremely fast. But the opening times of the overload protection devices are delayed. Fast tripping is vital in short-circuit protection.

Overloads cause thermal tripping but short circuits cause electromagnetic tripping in the protective devices.

Overloads shall be switched off only when the heat produced by them passes a pre-determined limit. For reason, the tripping time for smaller overloads is correspondingly longer than for heavier overloads. Short circuit currents shall be broken without any delay.

The reaction of protection devices

10. Sources

There are four basic sources of short circuit current:

  • Generators
  • Synchronous motors
  • Induction motors
  • Electric utility systems

All of these can feed a short circuit current into a short circuit.

The source of an overload can be any electrical load.

Continue Reading

Previous: Electrical Safety Devices That Can Be Found At Home: Top 10
Next: Type 1 & Type 2 Coordination: Basics, Comparison, Benefits

Related Stories

Dual Function Circuit Interrupter From A to Z: Dual Function Circuit Interrupters
  • Electric

From A to Z: Dual Function Circuit Interrupters

electricalterminology 13 hours ago
Advantages and Disadvantages of Incandescent Lamps Advantages and Disadvantages of Incandescent Lamps
  • Electric

Advantages and Disadvantages of Incandescent Lamps

electricalterminology 2 weeks ago
VFD Parts and Functions VFD Parts: A Guide to Their Essential Functions
  • Electric

VFD Parts: A Guide to Their Essential Functions

electricalterminology 2 weeks ago
Applications of 3 Phase Induction Motors in Industries Applications of 3-Phase Induction Motors in Industries
  • Electric

Applications of 3-Phase Induction Motors in Industries

electricalterminology 2 weeks ago
Advantages of DC Motors Advantages of DC Motors: Power and Performance
  • Electric

Advantages of DC Motors: Power and Performance

electricalterminology 2 weeks ago
Applications of AC Motors Applications of AC Motors: The Versatile Uses of Them
  • Electric

Applications of AC Motors: The Versatile Uses of Them

electricalterminology 2 weeks ago

Posts List

Advantages of Transducers Advantages of Transducers for Optimal Measurement

Advantages of Transducers for Optimal Measurement

Advantages of Infrared Sensors Advantages of Infrared Sensors: Improved Accuracy and More

Advantages of Infrared Sensors: Improved Accuracy and More

VFD Faults Causes Prevention Techniques VFD Faults: Causes and Prevention Techniques

VFD Faults: Causes and Prevention Techniques

Advantages of PCB Advantages of PCB (Printed Circuit Board) in Electronics

Advantages of PCB (Printed Circuit Board) in Electronics

Diode Failures Causes Prevention Tips Diode Failures: Causes & Prevention Tips

Diode Failures: Causes & Prevention Tips

PLC Selection PLC Selection 101: Tips and Tricks for a Successful Choice

PLC Selection 101: Tips and Tricks for a Successful Choice

Categories

  • Electric
  • Electronics
  • Manufacturers & Brands
  • Uncategorized

Pages

  • About Us
  • Affiliate Disclosure
  • Contact

Recent Posts

  • From A to Z: Dual Function Circuit Interrupters
  • Advantages of Transducers for Optimal Measurement
  • Advantages of Infrared Sensors: Improved Accuracy and More
  • Advantages and Disadvantages of Incandescent Lamps
  • VFD Parts: A Guide to Their Essential Functions
Copyright © All rights reserved. | Magnitude by AF themes.
We use cookies to ensure that we give you the best experience on our website. If you continue to use this site we will assume that you are happy with it.Ok