What Is The Difference Between Relay and Circuit Breaker? . In the electrical branch of engineering, a switch is a vital component. It helps to connect or disconnect the conducting path in the circuit. This interrupts the current from one conductor to another.
Relays and circuit breakers play an important role in the circuit.
Relays and circuit breakers may get a little intimidating to understand. There are many Relays and circuit breaker manufacturers in the market and it gets difficult to choose from.
This article will help you understand the difference between relays and circuit breakers and find the best circuit breaker for you.
Read More : What is an Oil Circuit Breaker?
What is a Relay?
A relay is a switch in small current circuits. It is used to sense, detect and control the fixed and moving contacts electromagnetically or electrically. It is an electrical switch and its function is only to detect an error in the fault.
It also acts as a protective device that alerts the circuit breaker when a fault is detected in the circuit. The circuit breaker then proceeds to respond to either make or break the circuit based on the information received.
Relay is used to switch small currents in the circuit. Relay is found in devices such as small motors and solenoids. They are not power-consuming devices and produce low ampere voltage.
Read More : Can We Use AC Circuit Breaker for DC Circuit and Vice Versa?
Needless to say, Relay can control large amperes and voltages in a circuit through an amplifying effect as a small voltage amplifier when the current flowing through the relay coils is switched from the contacts.
Relay comprises electromagnets and these electromagnets get energized when the current flows through it.
When the voltage of the current is very high, the electromagnets can pull the contacts towards themselves when required. This breaks the circuit instantly.
- Reed Relay
- Thermal Relay
- Hybrid Relay
- Solid State Relay
- Electromagnetic Relay
What is a Circuit Breaker?
Read More : Difference between Circuit Breaker and Isolator / Disconnector
Circuit Breaker is an automated electrical switch that is designed to prevent and overcome any damage from short circuits and overload. The switch is electromagnetic. The circuit breaker works on the principle that when there are short-circuit or overload-related situations, the relay detects the fault, detects the amount of current, and transmits signals to the switch. The breaker design is created in a way that it performs the task of closing and opening the contacts within the system within a short duration of time. The circuit breaker collects the signals and controls the opening and closing of the fixed and moving contacts to protect in the case of excessive current. The fixed and moving contacts work as electrodes inside the circuit. The circuit breaker can use the relay to determine any fault and react accordingly. Under normal conditions, the circuit is closed and does not open automatically. It only opens when a fault is detected in the system. The circuit breakers are broadly classified as hv circuit breakers (High Voltage), mv breakers (Medium Voltage), and low circuit breakers.
- Vacuum circuit breaker
- Airblast Circuit Breaker
- BOCB circuit breaker
- SF6 Gas Circuit Breaker
- MOCB Circuit Breaker
- Plain Air Circuit Breaker
Differences Between Relay and Circuit Breaker
Even though Relay and Circuit Breaker services seem similar to each other. Here are some key differences that you need to note between both of them.
The prime difference between Relay and Circuit Breaker is that electrical device that sends off signals to the circuit breaker regarding the amount of current flowing through the circuit and senses any faults. The circuit breaker receives the signal and responds by deciding whether to interrupt the flow of current in the system or not. It breaks the signal when it receives the signal from the relay in the case of a short circuit.
The differences between Relay and a Circuit Breaker is based on the grounds of the following:
Read More : How to Find the Number of Outlets on a Single Circuit Breaker?
| Characteristics | Circuit Breaker | Relay |
| Symbol |
|
|
| Construction | Circuit Breaker is the combination of internal electromechanical switch and relay mechanism which interrupts the circuit in case of short circuit or overload. | The coil inside a Relay creates electromagnetic field while the solenoid as moving part known as armature opens and closes the contacts when coil is energized. |
| Function | Circuit Breaker provides interruption only. Faults detection is performed by relay inside circuit breaker. | Relay is a switching device that opens and closes the contacts electronically or electromechanically. |
| Working Principle | Circuit Breaker automatically breaks the connected circuit when receives an error signal sensed by a relay inside CB. | Relay act as a switching and sensing device and sends the fault signal occurred on power system to the circuit breaker. |
| Operation | Circuit Breaker makes or breaks the circuit contacts when needed. | Relay only sense the error signal and send it to the circuit breaker. |
| Types | MCB (Miniature Circuit Breaker), ACB (Air Blast), VCB (Vacuum), SF6 etc. | SPST, SPDT, DPST, DPDT, EMR, SSR, Electromechanical, REED and Hybrid Relay etc. |
| Type of Device | Circuit breaker is a switching device act as circuit disconnection or isolation. | Relay is a sensing and controlling device act as a switch when needed. |
| Voltage Level | Circuit Breaker operated on low as well as high power and voltage level and acts automatic on load devices. | Relay operates on low power and voltage input signal with guaranteed isolation when needed for operation. |
| Controlling the Circuit | Circuit Breaker used to control one per circuit same like a switch. | Relay is used to select or control one among number of circuits. |
| Used as an Amplifier | Circuit Breaker can’t be used as an Amplifier. I.e. It only receives signal from a relay and make decision based on it. | Relay act as an Amplifier. I.e. it turns one signal into many signals e.g. turn a low-voltage signal into a high voltage signal, or vice-versa. |
| Applications | Circuit Breaker are used in
|
Relays are used in:
|
Read More : How to Find the Number of Outlets on a Single Circuit Breaker?
Different Characteristic of Relay and Circuit Breaker
- A Relay can be Directional and Non-Directional, whereas Circuit Breaker is Non-Directional only.
- A Relay only provides signals to the circuit breaker in case of fault conditions while circuit breaker act as automatic circuit making or breaking device based on the information provided by relay signals.
- Relay only sense the error and inform the circuit breaker i.e. it won’t break the contacts. Circuit breaker has both abilities of making and breaking the circuit automatically, manually or by remote control.
- A Relay is a switch acting as a sensing device whereas, circuit breaker is is used for disconnection and isolation of the circuit.
- Relay can be used as amplifier in case of discrete signals i.e. it converts one signal into many, amplify a low voltage signal into a high voltage signal and vice versa. Circuit breaker can’t be used as amplifier.
- A relay operates on low power and voltage input signals whereas, circuit breakers can be used for low as well high power circuit as its operation is automatic on load devices.
- Relays are controlling devices whereas Circuit Breakers are switching devices.
- A Relay can divert signals between two different electric circuits, whereas circuit breaker can only stop or flow the current in the circuit.
- A Relay won’t be able to prevent the arc. There may be a mechanism to detect the formation of arc and prevent it.
- Finally, a relay may be included in a Circuit breaker, but circuit breaker is not included in the relay.
Read More : Why VCB Circuit Breakers Outperform ACB in HV Transmission?
FAQs About Relay and Circuit Breaker
Q1. Can a relay replace a circuit breaker?
No, a relay cannot replace a circuit breaker as they have different primary functions.
Q2. Are circuit breakers reusable?
Yes, most circuit breakers can be reset and reused after tripping.
Q3. What is the lifespan of relays and circuit breakers?
Relays typically last for millions of operations, while circuit breakers are designed for thousands of fault interruptions.
Q4. Which is more cost-effective: relay or circuit breaker?
Relays are generally more cost-effective due to their simpler design and specific applications.
Related Topics
-
How to Wire 8-PIN Relay for Holding or Latching Circuit?
-
What Are The Types of Relays?
-
How to Reverse Operation of Photo Eye for Motor Using Relay?
-
How to Control a Three-Phase Motor Using Solid-State Relay?
-
Why Are There Different Types of Relay Protection in Power Systems?
-
Why VCB Circuit Breakers Outperform ACB in HV Transmission?
-
How to Wire a GFCI Circuit Breaker? A Step-by-Step Guide
-
Types of Circuit Breakers
-
Vacuum Circuit Breaker (VCB)
-
What Does B20 Mean on a Circuit Breaker? A Detailed Explanation for Beginners
