Are you considering upgrading your infrastructure? Perhaps you are a building development company working on new projects? If you are keen to make sure you are making the right decisions for your business, the smartest choices, then this article will guide you through that.
In this article we will look at low and high voltage, what they are, what switchgear is, and the key things you (and your company) should be aware of.
What is Switchgear?
Switchgear refers to a combination of fuses, electrical disconnects switches, or breakers which are used to isolate, protect, and control electrical equipment or gears. They are used to de-energise equipment for maintenance purposes, isolating a defective area. Each time a failure occurs on a power system (such as a short circuiting), electric equipment is at risk of being damaged by heavy currents overflowing the apparatus. This damage occurs as a result of the faulty
equipment not properly handling the current.
Switchgear allows for the current to be switched off, protecting the apparatus and allowing for maintenance work to be carried out without risking injury. Examples of switchgear include:
– fuses,
– switches,
– relays,
– isolators,
– circuit breakers, and
– contractors.
How Does Switchgear work?
Switchgear includes a circuit breaker, and a relay.
So, what happens in the switchgear process?
| Relay comes into action | This happens when a fault occurs |
| Trip circuit is closed | The relay triggers this, disconnecting the faulty line from the supply. |
| Operative and healthy sections run normally | Due to the selective shutting of the switchgear, no disruption to supply occurs |
The Main Functions of Switchgear
The main functions of switchgear are:
1. electrical protection,
2. electrical isolation of the electrical installation, circuits, or individual equipment,
3. Local or remote switching.
Without switchgear in place, whenever there may be a circuit failure on the power system, a heavy current runs through the electrical equipment in question. This heavy current can easily damage the equipment and disrupt the supply for any users. Therefore, installing switchgear (and doing so properly) is very important to make sure that your premises are safe, usable and protected.
What is Low Voltage Switchgear?
Typically, switchgear which has a capacity of up to 1 Kilovolt (KV) is considered to be low-voltage switchgear.
LV switchgear consists of:
1. low voltage switches,
2. earth leakage circuit breaker,
3. HRC fuses,
4. offload electrical isolators,
5. moulded case circuit breakers (MCCB), and
6. miniature circuit breakers (MCB).
The basic functions of LV switchgear are detailed below:
| For… | |||
| Electrical Protection | Overload Currents | Short-circuit currents | Insulation Failure |
| Isolation | Clearly indicated by and authorised fail-proof mechanical indicator | Interposed, or an empty, insulating barrier between |
| open contacts, which is cleary visible | ||||
| Control | Functional Switching | Emergency Switching | Switching off for Mechanical Maintenance | Emergency Stopping |
What is High Voltage Switchgear?
Typically, switchgear which has a capacity of over 36KV is considered to be high-voltage switchgear. The voltage is very high during the operation of this switchgear, therefore additional care is taken during the manufacturing process of HV switchgear.
An example of this is that HV switchgear has a high-voltage circuit breaker (which is a major part of the switchgear). Thus, these high-voltage circuit breakers need to have specific features which make it more safe and reliable than a typical circuit breaker.
This is important because operations which go wrong at voltage this high are far more dangerous than potential consequences for faulty low-voltage switchgear. Faulty operation is very rare within high voltage circuit.
Most of the time the circuits breakers remain in the ON condition, and may be operated after a long period of time. Thus, CBs must be reliable enough to ensure safe operation as and when they are required (this is a little more
spontaneous than most CBs have to be).
High voltage switchgears are categorised as:
1. Gas Insulated Indoor Type (GIS),
2. Air Insulated Outdoor Type,
The latter can be further classified into:
1. Dead Tanks Type Circuit Breaker, and
2. Live Tank Type Circuit Breaker.
What is the difference between these two outdoor types?
| Dead Tank Type | Filled with insulating medium, Has insulator supports |
| Live Tank Type | Cheaper, |
| Require less mounting space, |
The Essential Features of a High Voltage Circuit Breaker
The essential features of a high voltage circuit breaker, which ensure safe and reliable operation, must be capable of safely operating for:
1. terminal faults,
2. short-line faults,
3. transformer or reactors magnetizing current,
4. energizing long transmission line,
5. charging capacitor bank,
6. switching of out of phase sequence.
Typically, lower voltage switchgear can be stored within a building. Higher voltage switchgear, however, is usually externally mounted and insulated with air. This is a main difference between the two (aside from their capacity).
Why Should Your Business Care About Switchgear?
Switchgears allow for the isolation of certain, defective electrical equipment within a larger system. This provides vital protection for modern industrial premises and companies as they often rely heavily on high-voltage electricity. Modern switchgears have the capacity to conduct and control up to 1,100kV. Evidently, they are well-adapted for processing high-voltage electricity. Thus, if your company is one which relies on electricity (a lot of computers, variable usage, large spaces to light and heat) then it is important for you to consider the benefits of installing switchgear.
As aforementioned, switchgear trips the circuit and prevents defective equipment from causing more disastrous, costly damage to the wider electrical framework. Switchgear can save you a lot of money in repairs, and a lot of money in time potentially wasted by a supply issue to your company.
Maintaining Switchgear
It is also important for your company to be cautious and careful when it comes to the maintenance of newly or pre-installed switchgear. Properly working switchgear is essential for reducing the risk of issues before they arise, and
before they escalate. Plant supervisors are often hired to oversee the maintenance and quality of electrical equipment holistically, making sure it is all in prime working order. Investing in switchgear and plant supervisors may seem like a costly investment, but when your electricity supply isn’t being correctly regulated and monitored it is likely more costly damages will arise.
One method of checking switchgear is thermal imaging. This solution checks for ‘hot spots’ – this allows for technicians to see what is going on inside a circuit, without having to take it apart. If a hot spot is located, then the area can be addressed and fixed (before it turns into a costly problem).
Many businesses find that when a machine breaks – machines which can cost thousands of pounds, typically – it is as a result of an electrical fault. An electrical fault, usually, which would have been easily prevented by proper switchgear being installed. Switchgear helps you save time and money, valuable resources for any business or company.