Switchgear is a general term which involves protection, control, and switching equipment in a power system. According to IEC 60947, The Rated voltage of Low voltage switchgear (LV Switchgear) is up to 1000 VAC or 1500 VDC. You can watch this video to learn about different types of components:
Alternatively, here is the list of top 10 LV switchgear components:
An annunciator is a type of alarm indicator which provides a visual indication of fault alongside with audible alarm. Under fault conditions, the lamp flashing stars with an alarm. On noticing fault a power engineer pushes a button and the alarm becomes silent. The lamp, however, stays lit. After fault clearance, the lamp turns off. Modern control systems involve digital windows that are used for visually displaying the alarm notifications as well.
Busbars are the electrical nodes where power is gathered for distribution or further transmission purposes. Physically the busbar is a metallic rectangular conductor.
Circuit breaker plays a key role in protection and control of power systems. Usually, MCB (Molded case breakers) are employed on LV switchgear.
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- What is Breaking Capacity of Circuit Breakers and How it is expressed
- Justify the Rated Voltage V in MVA Breaking Capacity of Circuit Breaker
Control relays are used for controlling the electronic circuits. Mostly they are employed in control of other relays. They are used for sensing under and overvoltages and current reversal.
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A disconnector is installed for providing safe working conditions to the crew. A disconnector should always operate after opening the connected breaker. Disconnectors are generally equipped with:
- Auxiliary switching
- Gear Drives
- Push buttons
A major concern for switchgear designers is insulation. The major reason for insulation is to separate current carrying parts from each other as well as from earth. Air, gases, oils, vacuum, fluids, and solid materials can be used for insulation purposes. The choice of any material depends on the physical conditions.
Instrumentation transformers such as current and voltage transformers are used for stepping down the voltages for relays and other control equipment.
Metering equipment such as voltmeters, ammeters, wattmeters, DMPS is used for measuring different parameters such as voltage, current, power.
Protection relays are used to signal an alarm to elements of power so as to remove the component in case of an abnormal condition.
The entire list of LV switchgear components is very extensive and there are hundreds of components. However, all these components can be classified in one of above types. List of some other components:
- Auxiliary relays
- Auxiliary switches
- Control switches
- CB Accessories
- Earth switches
- Gas density monitor (In case of gas breakers).
- Generator voltage relays
- Interlocking equipment
- Junction box
- Liting devices
- Motor protection switches
- Push buttons
- Signal lamps
- Spring set
- Tripping coils