Have you heard about the Load break switch before? It’s one of the substation switching devices. Today we are going to acquainted with this device. Before the detailed presentation, I want to brief you on the switchgear system, in a nutshell, using a nice example. Now, the thrill goes on your mind what the example is going to be? Let’s see.
Switchgear System and Night Guard
We all dwell in a building. The house owner hires a security guard with a view to protecting the house from thieves, robbers. That’s why we can go to sleep at night without any anxiety. Similarly, imagine a power system as a building.
Then switchgear system will be the night guard of this system. You can assume the power line faults as thieves, robbers. A switchgear system is an assembly of switching and controlling devices. Load break switch is a fruit of that garden.
With the controlling device, you can turn a line on or off and the protective devices automatically disconnect the line in case of an error (overload, short circuit, etc.). That is, if an error occurs, the circuit breaker automatically closes the line. The relay helps the circuit breaker in this work.
It is the relay’s responsibility to detect that the error has occurred. As soon as the fault is detected, the relay circuit instructs the breaker to stop the repair or line. Sometimes you will see the alarm circuit is connected with a relay. This relay turns up the alarm circuit when an error occurs.
What is Load Break Switch?
If I express in a very simple manner, a load break switch is just a switching device that is used for switching in HT line or 11kV line.
Now, a question has arisen in your mind that, if we use a load break switch then why do we use VCB in the 11kV substation?
Let’s clear the vague concept. If power transformer ratings are below 500 kVA then we use a load break switch. You can compare the load break switch to a brake of a car. When we see any obstacle on road, we pause the car. Like this, LBS helps to stop the power flow when a short circuit fault occurs in the HT line.
Detail Informations about load break switch:
- Firstly, the 11 kV three-phase line from the pole enters the potential transformer. The indicator lamp of the panel will light up as soon as the 11 kV supply is received.
- This potential transformer displays on the voltmeter by measuring the incoming HT supply at every moment. If the voltmeter is analog, the value of the voltage has to be seen with the selector switch.
- After that, it enters the current transformer via busbar and HRC (High Current Rupturing) fuse. The reason for using HRC Fuse is that if there is excess flow, it will melt itself and protect the system.
- The current transformer measures the current and shows the text of the current on the emitter attached to it. To view this text in the analog emitter, the selector switch needs to be used.
- The load break switch panel is grounded for extra protection.
- It has an isolator attached to it and it is mechanically controlled by the operator. It is connected by the key so that only one can interfere with this work.
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