A broad range of low voltage switchgear is available today to meet different applications. To make informed decisions, customers must acquaint themselves with this type of switchgear. That’s what this easy-to-read guide will do and help you understand low voltage electrical switchgear in a non-technical way.
What is Low Voltage Switchgear?
Low voltage or LV switchgear is a type of equipment used to centrally monitor and control low voltage power systems. These are systems rated 1000 volts and below. LV switchgear is commonly used in residential, commercial, industrial, and even utility applications.
It’s also the most installed. According to a report by Global Market Insights, the global low voltage switchgear market is estimated to grow from USD 67 billion in 2022 to USD 136 billion by 2030, at a CAGR of 8% during the forecast years.
This is significant market growth, and attributable to the increasing demand for effective power distribution in various end-use industries. LV switchgear is available in a variety of voltage levels up to 1000 AC voltage (up to 1500 volts DC) and current levels up to 6000A.
Low Voltage Switchgear Function
From the low voltage switchgear definition, it’s evident that the equipment is used for a variety of purposes. One of its important functions is to protect against overloads or short circuits in electrical systems. This is accomplished through the use of circuit breakers that automatically trip or open when they sense a fault.
In addition to protecting against electrical faults, low voltage switchgear and control gear assembly is also used for controlling and regulating power in electrical systems.
Yet another low voltage switchgear function is to provide a safe and convenient way to disconnect power from electrical equipment or systems. This is made possible by the use of disconnect switches, which can be manually operated or remotely controlled.
Low Voltage Switchgear Design
Low voltage switchgear manufacturers use various design guidelines based on, one, the type of application and, two, customer requirements. The most typical design has the breaker at the bottom, bus bar in the middle, and cable compartment at the rear.
In a few applications, the cable compartment is located next to the breaker compartment and accessible from the front. That said, the low voltage switchgear design follows a common configuration where the assembly is composed of these 3 major parts:
- Breaker bar compartment
- Bus bar compartment
- Cable compartments
Break Bar Compartment
The breaker compartment is where the circuit breakers are located, arranged in compartments. Typically, each breaker will be housed in a separate compartment from the others. Low voltage switchgear uses molded case circuit breakers, MCCBs
Bus bar Compartment
Located in the middle of the low voltage switchgear assembly is the bus bar compartment. This is the part of the system that carries and distributes power from the incoming power cables to the various circuit devices. The bus bars are typically made from tin-plated copper or silver and either vertical or horizontal.
The cable compartment is where the cables are terminated. In most types of LV switchgear, this compartment is located in the rear and provided with doors for access. In a few others, it’s located and accessible from the front. This design makes installing a low voltage switchgear structure against walls possible.
Low Voltage Switchgear Components
LV switchgear consists of various electrical devices. These are normally enclosed in a grounded metal enclosure, which may or may not include draw-out cabinets. Read below for more about these parts.
Low voltage switchgear components include switching, interrupting, and controlling devices that are used to manage the distribution of low voltage electrical power. The main types of components found in low voltage switchgear are:
- Circuit breakers – these are used to protect against overloads and short circuits
- Disconnect switches – these are used to disconnect power from electrical equipment or systems
- Transformers – these are used to convert between different voltage levels
- Fuses – LV switchgear will also contain fuses, which are used to protect against overcurrents
- Relays – these are used to monitor and control the operation of circuit breakers and other electrical devices. Act as overvoltage sensors
- Disconnectors – also called isolators, these devices disconnect parts of an electrical system from the power supply
- Busbars – metallic conductors used to carry and distribute power within the switchgear enclosure
- Insulation – to provide electrical insulation between live or current-carrying components and other parts
There are several other LV switchgear components such as switches and metering devices. The above list covers the most commonly found parts.
Low Voltage Switchgear Ratings and Standards
Various industry standards govern the production of low voltage switchgear products. These include requirements for safety, rated voltages or current, and so on. Standard low switchgear ratings are listed below
- A maximum voltage of up to 635 V
- Continuous current of up to 10 000A
- Short-time withstand current of up to 100 000A, 30 cycles
- Short circuit withstand current of up to 200 000A
- Power frequency 50 and 60Hz
- Insulation level of up to 2.2 kV
These ratings are based on various standards and organizations including: ANSI/IEE C37.20.1, ANSI/IEE C73.20.7, UL1558, and UL1066. Other low voltage switchgear standards that manufacturers base their products and manufacturing methods on include NEMA and ISO standards.
Low Voltage Switchgear Types
Different switchgear is used in different environments and applications. LV switchgear can be classified into several types, depending on the application and voltage level. These include switchgear for indoor and outdoor spaces. The most common types of LV switchgear are:
- Metal enclosed low voltage switchgear.
- Metal clad low voltage switchgear
- Indoor low voltage switchgear
- Outdoor low voltage switchgear
- Air-insulated low voltage switchgear
- Gas-insulated low voltage switchgear
Metal Enclosed LV Switchgear
Metal enclosed LV switchgear contains circuit breakers, bus bars, and other components in a closed steel cabinet without the need for barriers. These systems are generally used for indoor applications at voltages up to 1000 V AC and up to 1500 volts DC.
Metal Clad LV Switchgear
Metal clad low voltage switchgear is similar to metal enclosed switchgear, but with the addition of a compartmentalized structure. That means the different components are housed in separate metal enclosures. This low voltage switchgear design increases operator safety while also making the equipment easy to maintain.
Indoor LV Switchgear
Indoor low voltage switchgear is designed for use in buildings or facilities with limited space. These systems typically contain circuit breakers and bus bars in a metal cabinet or enclosure for indoor applications. Indoor LV switchgear is mostly protected from the environment, but may be subjected to humidity and other indoor conditions.
Outdoor LV Switchgear
Outdoor low voltage switchgear is designed to be used outdoors in harsh environments such as extreme temperatures, high humidity, or wet conditions. These systems are often enclosed in a galvanized steel cabinet or enclosure and contain components such as circuit breakers, disconnect switches, fuses, and surge arresters.
Low Voltage Switchgear Maintenance
Switchgear must operate correctly, or the safe and reliable operation of electrical systems and equipment would be at risk. That’s why its maintenance is so important. By keeping your switchgear in good condition, you can avoid costly repairs and downtime.
Low switchgear maintenance involves a number of activities and different timeframes for them. Before we can look at these maintenance activities, here is a glimpse of what could cause your switchgear installation to age or get damaged.
Your low voltage switchgear assembly is subjected to several conditions such as:
- Relative humidity or water intrusion
- Extreme heat
- Salt condition
- Corrosive environments
- Current harmonics
- Load voltages
Low Voltage Preventive Maintenance
It’s recommended to ensure both preventive and conditional switchgear maintenance – and to keep a formal document indicating the planned and completed activities.
Low switchgear preventive maintenance refers to the activities that are done on a regular basis to avoid problems and keep the equipment in good condition. The main maintenance activities for low voltage switchgear are:
- Visual inspections
- Wiping and cleaning
- Tightening of connections
- Replacement of parts
- Functional testing
- Measurements and monitoring
These activities should be done according to the manufacturer’s recommendations. Low voltage switchgear manufacturers will also usually provide maintenance intervals for their products, which range from several months to years.
Low Voltage Switchgear Selection Guide
Because there are many variables to consider, the selection of LV switchgear is becoming more software-based. Different combinations are considered and modeled to arrive at the best solution. Having said that, the following low voltage switchgear specifications and other needs must be considered:
- The system voltage
- The current rating
- The short-circuit withstand capability of the switchgear
- Environmental conditions such as temperature and humidity
- The amount of space available for installation
- The required level of protection from electrical hazards
Other factors such as ease of operation and maintenance, the specific low voltage switchgear price, and lead time may also influence the selection of LV switchgear. Overall, the switchgear must satisfy these requirements.
- Provide acceptable performance under normal conditions
- Be able to safely interrupt all prospective short-circuit currents up to the maximum value that could occur in the system
- Withstand temporarily, without damage, all prospective short-circuit currents that could flow through it while remaining closed
- Restrict the rise of voltage across its terminals to a value that will not cause endangerment or damage to any equipment connected to it
- Conform to the required regulations for electrical equipment and safety in your region
It is also important that the LV switchgear can be operated safely and reliably under all conditions, including those of abnormal system operation.
With the rising demand for effective power distribution and management in various facilities, the need for low voltage electrical switchgear has never been greater. Manufacturers, on the other hand, are designing increasingly compact and efficient products to meet this demand. As technology advances, the capabilities of low voltage switchgear continue to increase. This is good news for consumers as it provides more options and flexibility when choosing a product.