One miscalculation of routine maintenance could be life-threatening. Proper servicing of electric systems involves high levels of safety. This is the reason why Earthing switches are important. Earthing switches enhance system performance, safety, and the ability to meet modern electrical requirements. In this blog, we’ll cover the earthing switch thoroughly, its uses, types, maintenance, and how it differs from a disconnector and a circuit breaker.
1) What is an Earthing Switch?
An Earth switch is an isolating device in an electric system that serves a safety function by providing a short circuit so that current flowing through unwanted paths is redirected to the ground.
The main purpose of an earthing switch is to provide safety against electrical risks and prevent technological faults. The important parts include the control switch, terminals, and contacts. Earth switching can be operated manually or automatically, depending on the system’s design. Well, an earthing switch can safely manage powerful voltages and large quantities of electrical currents.
2) Function of an Earthing Switch
The earthing switch has many functions, but its most important role includes the following:
a) Safety during Maintenance: When workers or operators are maintaining or repairing electrical equipment, the earthing switch cuts off the power to the system and grounds it so it can be operated safely.
b) Protection for Equipment: An earthing switch keeps components safeguarded from electrical faults and helps convert dangerous electric current to harmless current by safely directing it to ground.
c) System Stability: It assists in maintaining system stability by preventing damaging fault currents from disrupting the entire electrical network.
3) Operating principle of the earthing switch
The basic functioning of an earthing switch is straightforward. By the way, have you ever thought about how dangerous currents are safely discharged before maintenance begins? The answer is found in the operating principle of an earthing switch that ensures protection for individuals and equipment during electrical work. Let’s take a look!
- Detection of fault: The switch can be operated manually or automatically, depending on the system control. After detection of a fault, the switch creates a path that connects the circuit directly to the ground and transforms it into an “earthing” mode.
- Current Flow: The switch closes the circuit to earth and ensures that all leakage currents will flow to the ground.
- Disconnection: The earthing switch will remain in a closed position only when there is a fault or during maintenance works. Once the fault is recovered and maintenance work is done, the switch is opened and the system returns to its normal functioning state.
So, the earthing switch works mainly by preventing fault currents, such as those from short circuits. The switch provides controlled grounding, which allows it to eliminate hazardous current without impacting other parts of the system.
4) Earthing Switch in Low-Voltage Systems
In low-voltage environments, the earthing switch guarantees the safety of electrical systems. It functions as a protective measure for people and equipment, keeping them safe from harm.
- Primary Role: For systems with low voltage below 1,000 volts, the switch prepares a circuit for maintenance by connecting the circuit to ground for the safety of workers.
- Protection Against Electric Shock: Prevents electric shocks from occurring on the site by controlling the flow of electric current to the ground.
- Used with Other Devices: Works with other protective devices such as circuit breakers or disconnectors, to ensure reliability and safety in an entire electric system.
- Ensures Safe Maintenance: It keeps the maintenance team safe by discharging the electrical energy that could cause danger during maintenance.
5) Earthing Switch in High Voltage Systems
Increased protection is necessary for high-voltage systems, and this is where the earthing switch comes into play. A voltage above 1000 volts is used in substations and transmission lines. This switch safeguards maintenance workers by grounding live parts before work begins. What happens is that the earthing switch quickly discharges residual voltage for lower shock risk.
For safety improvements, earthing switches are commonly fitted with electrical or mechanical interlocks. These interlocks make it impossible for the switch to be operated unless the circuit is verified to be de-energised, preventing accidental grounding of energised circuits.
6) Typical Applications of Earthing Switch
Earth switches are utilised extensively in electrical systems where safety is a prominent focus. They are most critical during maintenance and other repair activities.
- Substations: Substations are the best locations for earthing switches. They ground high-voltage equipment before maintenance to safeguard workers from electric shocks.
- Switchgear Panels: Switchgear panels are equipped with the earthing switch in medium and high voltage to discharge any stored energy.
- Industrial Plants: In factories and heavy industries, earthing switches are applied to section off isolated specific parts of the plant for repairs without stopping the entire plant.
- Power Transmission and Distribution Lines: Earthing switches are used in grounding remote power lines during maintenance or when resolving faults. This enhances safety by preventing electric shock due to residual electrical energy discharges.
- Renewable Energy Systems: In solar and wind power stations, these switches are used in the systems to connect them to the ground.
- Transportation Systems: These switches are found in rail and metro power networks. These switches provide safe isolation during electrical works.
Earthing switches are enabled where electric circuits require earthing, guaranteeing the prevention of electrical mishaps. Their implementations ensure worker safety and system protection.
7) Types of Earthing Switches
Each type of earthing switch is made differently for various use cases, applications, and voltage levels. Choosing earthing switches with precision is critical to maintaining electrical safety and preventing hazardous faults. The different types of earthing switches are:
i) Manual Earthing Switch
As its name suggests, this can be manually operated, which is both less complicated and cheaper than the others. It is used where no automation is required, which makes it safer.
ii) Motor Operated Earthing Switch
Motor-operated switches are a more advanced type than others. Motors are used to automate these switches as they are used in systems with remote and quick response applications. Motor-operated earthing Switches are commonly seen at substations and in large-scale industrial setups.
iii) Spring-operated Earthing Switch
The spring-operated earthing switch is used in high-voltage applications. Operated Earthing Switches provide speedy responses by utilising spring energy for opening and closing switches. It makes them very effective during emergencies where speedy responses are a necessity.
iv) High-Speed Operating Earthing Switch
For very fast operation within milliseconds, high-speed earth switches are the perfect solution. These switches are an essential part of protection systems. They eliminate the possibility of electrical accidents.
v) Maintenance Earthing Switch
These switches are best used during scheduled maintenance as they provide safe grounding before the technicians begin work.
Every type has different functions in various electrical systems. With the provided setup, for low, medium, or high voltage, you can select the switch that balances safety, speed, and controls the system efficiently.
8) Electrical Symbols of the earthing switch
The two-pole earthing switch symbol in electric diagrams serves the purpose of showing that a switch is made which connects a certain part of the circuit to ground. Typically, it has two constituent parts: a switch line indicating that it is possible to open or close the circuit, and the ground symbol composed of three lines arranged as a triangle.
This illustrates that the switch cuts off the current and directs it into the earth when it becomes necessary. It aids the electrician and engineer to know where the safety ground is placed in the system. In addition, if the switch is motorised or part of a more complex apparatus, additional markings could also be present adjacent to the symbol.
More often than not, this symbol is used in schematic diagrams in order to indicate points which may be easily serviced or the system devoid of inactive potential which may in fact be hazardous. It is minimal in size but crucial in protecting systems from energising faults.
9) Earthing Switch in Substations
The security of substations is essential in power systems, and so earthing switches are important. In substations, these switches are;
a) Securing the Safety of Employees: Switches used within substations are set up to ground circuits performing maintenance work, which protects workers from the risk of electric shocks.
b) Secures Safe Isolation of Parts with High Voltage: The Earthing switch isolates dangerous equipment and sections so that there cannot be any accidents during inspection or repair.
c) Grounded Close to Circuit Breakers: These circuits are often associated with disconnectors or circuit breakers, so there is an easy possibility of control.
d) Active During Emergencies: In substations, the earthing switch is very helpful in case there is a fault and needs to be corrected, and the system needs to be grounded without access to advanced components.
e) Serves as a Parameter of System Dependability: Substation actively supports the system, and serves as a control for infrastructure systems in a building.
f) These bear Substation Safety Designs: The earthing switches are equally designed to adhere strictly to the safe policies of relevant substations.
g) Controlled Manually or Automatically: The switch has manual control or programmed controllers, depending on the size or type of the substation.
10) Earthing Switch in Switchgear
Are you curious about how modern switchgear maintains safe procedures during high-voltage functions? Here’s what earthing switches do for it:
- Complete Protection During Servicing: Earthing switches on switchgear circuits are used to ground the circuits prior to inspection or servicing. This step helps to keep workers within the vicinity free from dangerous electrical risks.
- Discharge of Stored Energy: A charge may still reside within a system even after turning it off. The earthing switch serves to discharge it safely.
- For Use with Medium and High Voltage Switchgear: The switches are especially designed for medium and high voltage switchgears where safety and control are of absolute necessity.
- Along with Isolators and Breakers: An earthing switch is generally installed together with isolators and circuit breakers. This means that when these devices are opened, the earthing switch will connect the system to ground.
- Increases Equipment Life Span: These switches improve the life of the equipment by ensuring that the grounded system is not subjected to damaging electrical stress.
11) Earthing Switch for VCB (Vacuum Circuit Breaker)
In a system utilising Vacuum Circuit Breakers (VCBs), the earthing switch is crucial for safe operation. It serves the purpose of closing the circuit and earthing the apparatus before or after the operation of the VCB so that there is no current left on the line. This becomes very useful during maintenance or inspection activities.
Here’s why it matters:
- It enhances personnel safety when conducting maintenance on the system.
- Safeguard against equipment damage caused by unexpected damage.
- It ensures complete disconnection of the circuit before servicing.
Most importantly, VCB panels come with pre-wired earthing switches that enable quick grounding. They may be designed for manual or automatic control from the rest of the system.
To be noted taht the switch must fulfil criteria to bear the high-voltage operation levels managed by the VCB. Well, coordination of the breaker and earthing switch ensures uninterrupted safety from every view through the system.
Eberry Electric provides a complete selection of earthing switches for systems ranging from 3–40.5 kv, guaranteeing safety and protection in high-voltage applications. Our products, like the JN17-12/40 type, comply with IEC and GB regulations and have high resistance to short circuits, are built to withstand corrosion, and can be operated manually or remotely with ease. All products are perfect for contemporary safeguards on switchgear.
12) Common Faults and Maintenance of Earthing Switch
Like all other equipment, earthing switches may face a fault if not maintained properly. They are vital for electrical safety in distress functions.
Common faults of the earthing switch
! Mechanical jamming: Dust, rust, or lack of lubrication causes the moving parts to seize.
! Worn-out contacts: Corrosion due to moisture or from hostile environments causes damage to the contact. Corrosion can damage metal parts and or reduce the performance of the earthing switch.
! Loose connections: With time, grounding wires or terminals can become weak, leading to the switches not functioning.
! Sensor or control failures: Automatic failure of sensors or control panels can stop proper switching.
! Insulation breakdown: Old insulation may lead to leakage currents and short circuits.
! Improper alignment: Misalignment of mechanical switch components can make the entire system harder to operate.
Maintenance of the earthing switch
! Regular inspections: Inspections after every 2 years can check the switches for any sign of fault or damage.
! Clean the unit: Keep the equipment free from noninstrumental dust, dirt, and any sitting debris not serving any function.
! Lubricate moving parts: Change the oils used to lubricate the parts, and keep the moving parts in proper working condition.
! Tighten connections: Ensure every terminal is tightened alongside every wire used in grounding.
! Replace worn parts: Any corroded or damaged parts must be replaced immediately.
! Check automation system: Check control circuits and sensors for proper functionality.
! Record maintenance: Maintain a record of all checks, evaluations, and repairs performed on the system.
13) Difference Between Earthing Switch, Disconnector, and Circuit Breaker
Have you ever thought about how various electrical appliances provide safety and control in a power system? This is all possible through the collaboration of an earthing switch, disconnector, or circuit breaker. Look at these one by one;
Earthing Switch: This device automatically provides electrical safety during maintenance operations by providing a path for electrical current to flow into the ground.
Disconnector: The Disconnector provides safe maintenance of the circuit by isolating portions of the circuit that have a fault. It does not interrupt the flow of current.
Circuit Breaker: This device interrupts the circuit by itself in the event of overloads, faults, or other overriding factors. Basically, the purpose of this device is to protect the equipment and personnel from damage.
| Device | Function | Safety role |
| Earth switching | Ground the circuit | Discharge charge |
| Disconnector | Isolate the circuit | Visual separation |
| Circuit breaker | Interrupt faults | Overload protection |
14) Conclusion
So, earthing switches are primary devices for maintaining safety, stability, and protection in today’s advanced power systems. They are essential in substations, switchgear, and vacuum circuit breakers (VCBs) for earthing as well as for clearing faults. Make sure your switches meet high standards of efficiency, security, and the standards of the power system. So, for this purpose, you can rely on Eberry. You can contact us by clicking here!
