RCCB & PRCD Tutorial | Working and Testing of Shockproof Technology

Hey, what's up, Guys! Akarsh here from CETech.

Electricity is one of the most basic needs nowadays. Whether in a city or in a remote village, Everyone uses electricity for one purpose or another. In fact, the lifestyle that we have today is totally dependent on electricity. We are surrounded by appliances that make our life easier but they are nothing without electricity. So electricity is an important part of our lives nowadays. But it can be dangerous and if not handled properly, it can be life-threatening too. There are cases where we see that some people died due to electrocution or a fire broke out in a building due to a short circuit resulting in some people losing their lives. These kinds of mishaps can be avoided by taking small precautionary measures. One of which we are going to discuss here today.

The device that we have today with us is a PRCD Adaptor named Life Savior from Havells. It is basically an adaptor that works on the principle of RCCB/RCD. It is a great device and a must to have with your appliances nowadays.

So if you are interested in this device and want to have some details about it, then read this article till the end.

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A residual-current device (RCD), residual-current circuit breaker (RCCB), or ground fault circuit interrupter (GFCI) is an electrical safety device that quickly breaks an electrical circuit whenever it detects a leakage current to the ground which is greater than its threshold. It is to protect equipment and to reduce the risk of serious harm from an ongoing electric shock. Injury may still occur in some cases, for example, if a human receives a brief shock before the electrical circuit is isolated, falls after receiving a shock, or if the person touches both conductors at the same time.

In an ideal current the current flowing through the live wire ought to be equal to the current returning through the neutral wire. This is the principle on which the Residual Current Circuit Breaker works.
In case an earth fault occurs, the current is able to find a way to the Earth via accidental means like touching a live wire. Due to this, the returning current via the neutral wire is reduced. The difference between the two currents is called Residual Current. RCCB is outlined in such a manner that it ceaselessly senses and compares any contrasts (residual current value) in the current between the neutral and live wires. Even a small change between the values would trigger the Residual Current Circuit Breaker and it will disconnect the circuit.

There are two types of RCCBs:-

1) 2 Pole RCCB: It is utilized in a single-phase supply that only contains a neutral wire and a live wire. It has two ends and at those ends, the neutral wire and live wire are connected. With the help of a rotary switch, you can switch the RCCB on and off. It also has a test button that assists in periodically testing the functionality of the RCCB.

2) 4 Pole RCCB: It is utilized in a 3-phase supply connection that includes a neutral wire and 3-phase wires. Again this has two ends where both the neutral wire and 3 phase wires are connected. This is the only difference between the 2 and 4-pole RCCB, the rest of the work is similar.

Havells Life Savior PRCD Adaptor is a (6/16) A Power Adaptor with built-in RCD. It comes with a shuttered socket for child safety. It has been incorporated with auto trip technology that automatically shuts off your appliances when it detects a current leakage. To detect the difference in currents or residual current. it uses the basic principle that the amount of current that is leaving the source and entering the source should be the same. So according to that whenever it detects a difference in the current, it automatically switches off the appliances connected. The PRCD eliminates the risk of electric shock and also limits the passage of current through any human body.

It has a visual detection of power on the front which shows when the adaptor is operating and when it is in the tripped state. The adaptor has a Test button and a reset button on it. The Test function is for checking any abnormality in the circuit and the RESET function is for switching on the appliance after its shut down. We just need to press the RESET button and the device will be ready again to be operated. Some Technical Specifications of the Adaptor are as given below:-

1) Current Trip Levels: It stands for the amount of residual current that is required to trigger the RCD. The Trip Level for this device is 30 mA which means that if the device detects a residual current of 30 mA or more, it will trip off immediately.

2) Rating: Rated 16 A / 250 V AC 50 Hz / 3000 W

3) Trip Response time: It is the time that the device takes to trip, once it detects the residual current in the circuit. The trip response time for this adaptor is less than 40 ms.

4) It is a weatherproof transmitter that comes with IP40 protection.

So these were some of the details about the Adaptor from Havells. Now let us have a little demo of this to check how it operates.

CAUTION: The Things that I am going to do in this step can prove to be dangerous if not done with due care. So, I suggest not doing this on your own. But if you try this, then do it with proper caution otherwise you may get electric shocks.

In this step, I am going to create a situation that will be somewhat similar to the ones that occur in real life and results in a small residual current. I will expose the adaptor to that condition and will see if that works or not.

The items that are required for this step are as mentioned below:-

1. A 3 pin power plug
2. A power extension cord or a power strip
3. 5k ohm resistor
4. Havells PRCD Adaptor

The steps for performing the demo are as given below:-

• Take the 3-pin power plug and remove its back plastic cover to expose the inside of its pins.
• Connect the Earth Terminal and Live Terminal of the plug to each other through the 5k ohm resistor. This will result in a residual current in the circuit which will be approximately equal to 45 mA which is sufficient enough to trigger our Adapter.
• Now ensure that the power strip is in the off state at the moment and after that connect the open plug to one of the ports of the power strip.
• Now connect the Adaptor to a Power supply plug in your house that has electricity at that time. Make sure that the switch is off at the moment.
• Now plug in the power strip plug into the Adaptor.
• Keep the power strip in the off state and then switch ON the main supply plug. You will see that the Adaptor will switch on and the power indicator will light up.
• Press the RESET button to make sure that the adaptor is not in the tripped state. Now keeping the main supply ON, Switch ON the power strip.

As soon as you turn ON the power strip. You will listen to a click sound and you will see that the PRCD Adaptor's power light has gone off and the power strip has also not turned ON even when the main supply is switched ON for both of these. This simply means that the adaptor has tripped off after detecting the residual current in the circuit. And in this way, you will see that the Adaptor is working as it should. You can do this thing again, this time without using the open 3-pin power plug that we used to see that it will not trip in that state.

So now as we have got some details about the PRCD Adaptor and we also have tested the device. Let us see what's on the inside of the Adaptor that makes its operation possible. By looking at the inside of the Adaptor we will have an idea of how the industry-standard thing works and on the basis of our understanding, we will see if it is possible to create a similar adaptor at our home with Arduino and other things. If possible we will see if we can integrate it with IoT to get some real-time metrics from the adaptor and analyze how the operations are going on. But for now, let's see what's on the inside of this Adaptor.

To open the PRCD Adaptor, we have to open 4 screws on the backside of the adaptor. Once the screws are open, you will be able to see the internal circuitry of the device. On the bottom, there is a Power plugin to which we connect our appliances and above that, we have a PCB containing the whole circuitry that is responsible for the tripping, reset, and testing mechanism of the Adaptor. There is an electromechanical system that will basically get the tripping done. A relay is present that performs the switching and apart from that, there is a coil that has both the Live and Neutral terminals connected to it. Basically, this will act as the Current Sensor and will detect the residual current. There are more elements like Capacitors, Transistors, and other custom parts present inside.

So these are some of the basic things that we get to know about the circuit after having a look at it. You cannot understand a circuit completely by just looking at it. So we need to analyze it further but we will keep that for next time and after analyzing the circuit, maybe we can imitate a similar thing using Arduino and other stuff. So that's it for this time. Hope you got some valuable information. We will be back with some more interesting things until then Enjoy Electronics.