• Product
  • Suppliers
  • Manufacturers
  • Solutions
  • Free tools
  • Knowledges
  • Experts
  • Communities
Search


What is a Backup Relay ?

Encyclopedia
Encyclopedia
Field: Encyclopedia
0
China


What is a  Backup Relay ?


Backup Relay Definition


A backup relay is an additional relay system that operates if the main relay fails, ensuring continued protection.


 

Function of Backup Relay


The primary function of a backup relay is to trip the circuit breaker when the main relay fails.


 

Reasons for Main Relay Failure


Main relays can fail due to mechanical defects, power supply issues, or problems in the CT/PT circuits.


 

Importance of Backup Relay


Backup relays provide an extra layer of reliability, essential for protecting expensive and high-voltage equipment.


 

Operation of Backup Relay


Backup relays are designed to act slower than main relays, stepping in only when the main relay fails.


Give a tip and encourage the author!
Recommended
Relay Protection Types in Substations: A Complete Guide
Relay Protection Types in Substations: A Complete Guide
(1) Generator Protection:Generator protection covers: phase-to-phase short circuits in stator windings, stator ground faults, inter-turn short circuits in stator windings, external short circuits, symmetrical overload, stator overvoltage, single- and double-point grounding in the excitation circuit, and loss of excitation. Tripping actions include shutdown, islanding, limiting fault impact, and alarm signaling.(2) Transformer Protection:Power transformer protection includes: phase-to-phase short
Echo
11/05/2025
THD Measurement Error Standards for Power Systems
THD Measurement Error Standards for Power Systems
Error Tolerance of Total Harmonic Distortion (THD): A Comprehensive Analysis Based on Application Scenarios, Equipment Accuracy, and Industry StandardsThe acceptable error range for Total Harmonic Distortion (THD) must be evaluated based on specific application contexts, measurement equipment accuracy, and applicable industry standards. Below is a detailed analysis of key performance indicators in power systems, industrial equipment, and general measurement applications.1. Harmonic Error Standar
Edwiin
11/03/2025
How Vacuum Tech Replaces SF6 in Modern Ring Main Units
How Vacuum Tech Replaces SF6 in Modern Ring Main Units
Ring main units (RMUs) are used in secondary power distribution, directly connecting to end-users such as residential communities, construction sites, commercial buildings, highways, etc.In a residential substation, the RMU introduces 12 kV medium voltage, which is then stepped down to 380 V low voltage through transformers. The low-voltage switchgear distributes electrical energy to various user units. For a 1250 kVA distribution transformer in a residential community, the medium-voltage ring m
James
11/03/2025
Why Monitoring Accuracy Matters in Power Quality Systems
Why Monitoring Accuracy Matters in Power Quality Systems
The Critical Role of Monitoring Accuracy in Power Quality Online DevicesThe measurement accuracy of online power quality monitoring devices is the core of the power system’s “perception capability,” directly determining the safety, economy, stability, and reliability of power supply to users. Inadequate accuracy leads to misjudgment, incorrect control, and flawed decision-making—potentially causing equipment damage, economic losses, or even grid failures. Conversely, high accuracy enables precis
Oliver Watts
10/30/2025
Related Products
Send inquiry
Download
Get the IEE Business Application
Use the IEE-Business app to find equipment, obtain solutions, connect with experts, and participate in industry collaboration anytime, anywhere—fully supporting the development of your power projects and business.