The ultimate guide to LV and MV switchgear - what you may not know...

Switchgear plays a critical role in the electrical power distribution system. It controls and protects electrical equipment and circuits by isolating faulty sections of the system and disconnecting them from the power source.

LV (low voltage) switchgear is typically used in buildings, while MV (medium voltage) switchgear is used in larger commercial and industrial facilities.

In this article, we will discuss everything you need to know about LV and MV switchgear, including their types, components, applications, maintenance, and safety.

Types of LV and MV Switchgear

As mentioned previously, there are several types of LV and MV switchgear, including:

Air-insulated switchgear (AIS): AIS is the most common type of switchgear, and it uses air as the insulating medium. It is simple to operate and maintain, and it is suitable for indoor and outdoor applications.

Gas-insulated switchgear (GIS): GIS uses a high-pressure gas such as SF6 (sulfur hexafluoride) as the insulating medium. It is compact and requires less space than AIS, making it suitable for high-density urban areas.

Hybrid switchgear: Hybrid switchgear combines the advantages of both AIS and GIS. It uses a combination of air and gas as the insulating medium, providing the best of both worlds.

Components of LV and MV Switchgear

LV and MV switchgear typically consist of the following components:

Circuit breakers - Circuit breakers are used to interrupt the flow of current in case of a fault. They protect the system by isolating the faulty section and preventing further damage.

Disconnectors - Disconnectors are used to isolate parts of the system for maintenance or repair work.

Earthing switches - Earthing switches are used to earth the equipment during maintenance work, ensuring that it is safe to work on.

Instrument transformers - Instrument transformers are used to measure voltage and current in the system.

Control and protection devices - Control and protection devices are used to monitor and control the system's parameters, such as voltage, current, and temperature. They ensure that the system operates within safe and optimal limits.

Applications of LV and MV Switchgear

LV switchgear is typically used in buildings for the distribution of electrical power to lighting, heating, and other small appliances. It can handle voltages up to 1000V and is rated up to 4000A.

MV switchgear is used in larger commercial and industrial facilities, such as power plants, manufacturing plants, and data centers. It can handle voltages up to 38kV and is rated up to 4000A.

Maintenance of LV and MV Switchgear

Regular maintenance of LV and MV switchgear is essential to ensure its safe and efficient operation. Here are some maintenance tips:

Visual inspection - Regular visual inspections can identify any signs of wear and tear, such as loose connections or damaged components.

Lubrication - Lubrication of moving parts can extend the lifespan of the switchgear and reduce the risk of breakdowns.

Cleaning - Regular cleaning can prevent the buildup of dust and dirt, which can cause overheating and other problems.

Testing - Regular testing can identify any faults or potential problems before they become serious.

Safety Considerations for LV and MV Switchgear

Safety is paramount when working with LV and MV switchgear. Here are some safety considerations:

Always follow the manufacturer's instructions for installation, operation, and maintenance.

Switch off the power and isolate the equipment before performing any maintenance or repair work.

Wear appropriate personal protective equipment, such as gloves, goggles, and ear protectors.

The main causes of switchgear failure and how to avoid them

Switchgear failure results from a number of different reasons. Some are due to problems with the equipment itself, while others are caused by external factors. Regardless of the reason, electrical switchgear failure can have serious consequences. Here is a list of the most common switchgear failure causes.

1. Faulty Switchgear Connections

A switchgear connection refers to the bolted, screwed, or welded joint between the different parts of the switchgear. Over time, these connections can loosen due to vibration or other factors. When this happens, it can cause an electrical arc that could damage the equipment or start a fire. This type of failure is often caused by poor switchgear maintenance.

2. Degraded Switchgear Insulation

Switchgear insulation is used to prevent electrical shocks. It can also help prevent fires by providing a barrier between live electrical parts and arc quenching or cooling. Over time, insulation can degrade due to heat, chemicals, or other factors. When this happens, it can lead to switchgear failure.

3. Improper Switchgear Service

Switchgear should be regularly serviced by qualified personnel. Switchgear service includes periodic cleaning, inspection, and testing. Sometimes, however, service intervals may be lengthened or skipped altogether. This can lead to a build-up of dirt, dust, and other contaminants that can eventually cause the switchgear to fail.

4. Old Switchgear Components

Like any other type of electrical equipment, switchgear has a limited lifespan. The older the switchgear, the more likely it is to fail. That’s why it’s important to keep up with the manufacturer’s recommended replacement schedule. This includes replacing old switchgear parts, as well as upgrading to new switchgear when necessary

5. Environmental Causes

Switchgear is designed to withstand a certain range of environmental conditions. However, extreme conditions can still lead to failure. This includes things like high humidity, high temperatures, or even salt air. External causes of switchgear failure also include animals, like rodents, getting into the equipment.

Here’s why your circuit breaker keeps tripping

Electrical switchgear regulates, protects, and isolates a power system with a variety of controls housed in a metal enclosure. It’s a vital system in industries that experience electrical faults or those that need to regularly de-energize equipment for maintenance, such as industrial environments and electrical utilities.

Switchgear contains fuses, switches, and other power conductors. However, circuit breakers are the most common component found in switchgear. During an electrical fault, a circuit breaker will sense the anomaly and interrupt the power flow, effectively limiting damage to the system. Because it’s designed to control the flow of power, switchgear plays a role in enhancing a facility’s energy efficiency and safety.

The five main reasons that circuit breakers keep tripping are:

1. Circuit Overload

2. Short Circuits

3. Ground Fault Surges

4. Defective Circuit Breaker

5. Arc Fault

Summary

Ultimately, you must make sure that your circuit breakers are in good working order. At Volt Logic, we can offer maintenance packages with all our switchgear, ensuring you get the best service possible.