What is Switchgear Panel and Types of Switchgear?

What Is Switchgear Panel?

Switchgear is an apparatus that is used for regulating, controlling, and switching the electrical circuit on and off in an electrical power system. Various examples of switchgear devices include fuses, switches, relays, potential transformers, lightning arresters, indicating instruments, and control panels.

Switchgear present in an electronic system is made up of electrical disconnect switches, circuit breakers, or fuses that are used for controlling, isolating, and protecting the electrical equipment. It is used for the purpose of de-energizing equipment so that the work may be done and for clearing the faults occurring downstream.

In earlier times, the central power stations used open knife switches that were mounted on insulating panels of asbestos or marble. Voltages and the levels of power escalated swiftly by creating openings with switches being manually operated. These were considered highly lethal for everything except for the isolation of de-energized circuits.

Switchgear equipment that is filled with oil allows the arc energy to be safely controlled and remain contained. By the early times of the 20th century, the switchgear line-up turned into a metal-enclosed structure having switching elements that were being operated electrically by using the oil circuit breakers.

Presently, the oil-filled equipment has been replaced by the air-blast, SF equipment, or vacuum. This allows the power levels and large currents to be safely controlled by the automatic equipment. Invented by the end of 19thcentury the high-voltage switchgear was used for the purpose of operating motors and electric machines.

Switchgear panels are found in transformer stations, commercial and industrial buildings, paper mills, metal smelters, distribution substations, and transformer stations. These are mainly used in places where the electric energy is distributed or utilized in various zones.   

What Is LT Switchgear Panel?

LT switchgear panel refers to the low-tension panel that is being manufactured and applied for controlling the distribution systems and power control of AC. This type of panel is mainly used in the indoor and outdoor substation, industrial enterprise, commercial or residential buildings that distribute power and. Further, this may also be used for controlling, introspecting, and protecting the circuit.

Types of Switchgear

There are primarily two types of switchgear which are indoor type and outdoor type. Output switchgear is used at places where the voltage is above 66kV. This is because, at places where high voltage is required, the building work increases the installation cost unnecessarily owing to the huge spacing that lies between the large size of insulators and the conductors.

When it comes to below 66kv, the building work can be easily provided for the switchgear at a reasonable cost. The switchgear of indoor type is mainly metal clad and compact; its compactness reduces the safety clearance level of operation, further reducing the area.

Further, there are three types of switchgear on the basis of voltage; these are low voltage, medium voltage, and high voltage switchgear. The power system dealing with up to 1 kV is termed as low voltage switchgear or LV.

This equipment comprises HRC fuses, offload electrical isolators, molded case circuit breakers, miniature circuit breakers, LV circuit breakers, switches, or the earth leakage. The power system dealing with up to 36 kV is termed as medium voltage switchgear or MV.

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This type of switchgear is available in diverse types like metal-enclosed indoor and outdoor types, without metal enclosure outdoor type, and so on. This type of voltage also includes various substation devices like bulk oil CBs, minimum oil CBs, air magnetic, vacuum, gas-insulated, etc.

In this type of switchgear, the disruption medium may be SF, oil, and vacuum. The primary condition in this type of power network is to break off the flow of current passing through the faulty condition in the system.

It is capable of interruption of short circuit current, ON/OFF operation, inductive current switching, and capacitive current switching. Further, it is also used in many special applications.

The power system dealing with more than 36 kV is termed as high voltage switchgear. It has been observed that when the voltage level increases, the arching gets generated as a result of high switching operation. Therefore, special care needs to be taken while designing the equipment. A high voltage or HV circuit breaker is the main component present in the equipment.

It is recommended that an HV circuit breaker must comprise of operational features that are both safe and reliable. Here, the switching operation of the HV circuit is rare and the CBS remain at an ON state on which the work may be done after some time. When needed, these must be reliable enough so that certain secure operations may be done.

The Function of a Switchgear

There are numerous functions of switchgear; it is used for protecting the equipment from fault currents and short-circuits. It not only increases the system availability by permitting more than one source for feeding a load but also gives isolation to the circuits belonging to the power supplies.

It is used for opening and closing the electrical circuits under various conditions both normal and abnormal. It may be operated manually in normal conditions so that the safety of the operator may be ensured and the electrical energy may be utilized properly.   

This is known for operating manually in abnormal conditions. However, once a fault occurs, the device detects it and the damaged part is being detached from the power system. Thus, it protects the power system. 

Components of Switchgear

There are two components of switchgear that are control systems and power conducting. The components of power conducting comprise circuit breakers, fuses, switches, and lightning arrestors that are utilized for interrupting the electric power flow.

Control systems comprise control panels, transformers such as potential and current protective relays, and the connected circuitry that monitor, control, and protect the various components of power conduction. Let’s further read about the evolution of switchgear.

Evolution of Switchgear

Switchgears belong to the electricity generation; the initial models were primitive as all the components were fixed to the wall. But afterward, these were mounted on the wooden panels. Later on, for the purpose of fire protection, these wooden panels were replaced by marble or slate.

This further led to an improvement as the measuring and switching devices could now be joined to the front while the wiring is on the back. The tumbler switch that has an ordinary fuse is considered the simplest form of switchgear.

This was used for protecting and controlling the equipment in offices, homes, and lights. For circuits of a high rating, HRC or high-rupturing capacity fuse in conjunction with a switch that may serve the reason of shielding and controlling the circuit. On a high voltage system, the switchgear cannot be used profitably. 

The switchgear equipment is basically concerned with interrupting and switching the currents that are present under various normal or abnormal operating conditions. If there is a higher rating circuit, the HRC or high-rupturing capacity fuse that is present in conjunction with a switch can serve the purpose of protecting and controlling the circuit.

When a fuse blows, it usually takes time to get replaced which creates an interruption in the services provided to the customers. The fuse cannot interrupt the large fault currents that are a result of the faults on the high voltage system.  

The lines and various other equipment began to operate at high voltages with the advancement of the power system. These are known for carrying on large currents. Every time a short circuit occurs on the system, the heavy current that is flowing through the equipment causes considerable damage.

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For the purpose of interrupting heavy fault currents, automatic or simple circuit breakers are being used. A circuit breaker is switchgear that may open or close the electrical circuit under various normal and abnormal conditions.

Features of Switchgear

Features of switchgear are numerous; the essential ones of it comprise quick operation, complete reliability, certain discrimination, and provision for manual control.  There has been a continuous trend of interconnection and an increase in the capacity of generating stations.

There is a need for switchgear that is reliable as it holds high importance. Switchgear is added to the power system for improving reliability so that when the fault occurs in any part, it may be operated for isolating the faulty section from the remaining circuit.

Every time a fault occurs in any part of the electric power system, the switchgear must be able to discriminate between the healthy and faulty sections. The faulty section must be isolated without creating a problem or raising an issue in the healthy section. This helps in ensuring the continuity of supply.

When a fault occurs in any part of the power system, the switchgear must be capable of operating quickly in order to avoid damage. This damage may be caused to transformers, generators, or any other equipment through the currents of short-circuiting.

If the fault is not cleared quickly, it may spread into the healthy parts of the power system creating problems in its normal working leading to shut down. Switchgear is further known for having a provision of manual control. Every time an electrical control fails, the required operations are carried out manually.

Switchgear Equipment

Switchgear covers various ranges of equipment that are concerned with interrupting and switching currents under different conditions comprising both normal and abnormal. It includes fuses, switches, relays, circuit breakers, and various other equipment.

Switch:

A switch is used for opening and closing the electrical circuit conveniently. It may be used in different conditions that may be full load or no load. However, it cannot interrupt the faulty currents. Every time the contact of switch is opened, an arc is being produced in the air present in between the contacts.

This is true in the case of circuits having high voltage and capacity for large currents. The switches may be classified into oil switches, air-break switches, and disconnecting or isolator switches depending upon the opening of their contacts.

Fuse:

A fuse is a thin strip or a short piece of wire which melts down when excess current flows through it for a sufficient time period. It is being inserted in series with the circuit which is to be protected. In the case of normal operating conditions, the fuse is known to the element it at a temperature that is below the point of melting.

It is known for carrying the normal load current without any overheating taking place. In cases when an overload occurs or a short circuit happens, the current passing through the fuse increases the element beyond the capacity that is rated.

This is known for raising the temperature that leads to the melting of fusing elements further disconnecting the circuit that is being protected by it. This is how the equipment and machines are being protected from any type of damage that is caused due to the excessive currents. A fuse is known for performing various interruption and detection functions.

Circuit Breakers:

A circuit breaker is switchgear equipment that is used to open and close the circuit under various conditions comprising of full load, no-load, and other faulty conditions. It is designed in such a way that it can be operated manually or by using remote under normal as well as faulty conditions.

The relay circuit is being used with a circuit breaker for the latter operation. The circuit breaker consists of fixed and moving contacts that are enclosed in a robust metal tank and further immersed in oil known as transformer oil.

Relays:

A relay is a device that is used for detecting the fault and supplying the information to the breaker for the interruption of the circuit. The main winding of the current transformer is being connected in series along with the circuit that is required to be protected. The initial winding comprises the main conductor.

The second circuit comprises the secondary winding of the current transformer that is connected to the relay operating coil. The third is the tripping circuit that consists of a supply source, relay stationary contacts, and a trip coil of the circuit breaker.

Where to Buy Switchgear?

It is always best to buy switchgear from a company whose products are of high quality, reliable and durable. Tesca is known for offering the best products to its customers for years. It is an ISO 9001:2015 certified and the manufacturer and exporter of the test, measuring, and technical education equipment.

It offers different types of switchgear panels such as automation panels, high-voltage indoor panels, and low-voltage panels. The automation panels further include a soft starter panel, SCADA, PLC panel, LV DC drive panel, and LV AC drive panel.

The high-voltage indoor panels include 23Kv panels, a vacuum switch, and 11Kv panels. The low-voltage panels include Modular PCC & MCC, DG Synchronizing, APFC, AMF, DBs, Intelligent MCC, and many more.

Tesca is known for offering excellent marketing and technical support and offers more than 3000 innovative products. With sales in 85 countries worldwide, it offers quality control at multiple stages. Additionally, it also provides hassle-free shipment ordering and quick response to all its customers.