A residual current device, or RCD, is a low voltage electrical apparatus. It automatically disconnects the protected section of the electrical circuit if a differential current of magnitude occurs. In different situations, it can exceed the permissible value, which is typical for this device. To make the right choice when buying and organizing electrical wiring, you need to study the types of RCDs.
Content
- Functions performed
- Mode of action
- Application area
Functions performed
The residual current device helps to save a person's life, to prevent possible electrical injury if leakage currents occur. In isolation, it is not uncommon for invisible or uncontrolled violations to occur. There is a wide and varied selection of devices on the market. They differ from each other in different characteristics.
As a result, people will be able to choose the best options that will suit their specific operating conditions. But it is also worth paying attention to the principle of operation of the RCD in order to understand its properties.
Protective device perform the following main functions:
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switching on consumers that are connected to devices and are under strong voltage; - reliable passage of the rated load current, if no false operation has occurred;
- under normal conditions, consumers that are under load are turned off;
- de-energization of a circuit that is under control if a critical value is reached and the difference between the outgoing and incoming current.
RCD helps protect a person from the effects of electric current, if devices or equipment are working in the room. Additionally, fire is prevented when the integrity of the wiring is broken. The RCD will not be able to turn off the excess current that flows through this device.
There is a possibility of breakdowns and malfunctions. That is why the residual current device is installed together with an automated circuit breaker that can withstand high loads. A device that performs the function of an RCD and a circuit breaker is called a differential machine.
In order for consumers to understand the wide and varied selection of models, there is an established classification. They differ in the following technical characteristics:
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action; - the maximum possible amount of current that passes through the device;
- the presence of a differential device, as well as the ability to adjust it;
- installation method;
- number of poles;
- working voltage value.
The choice is made depending on these characteristics. You can contact a specialist who will recommend the best option for installation. And he will also tell you the principle of operation of the RCD, depending on the state of the wiring and the location of the device.
Mode of action
Residual current devices are available with an additional power supply. It helps to ensure the smooth and efficient operation of the entire electronic circuit. Manufacturers make models that can do without a power source. In this case, the connection is due to the electromechanical design.
The efficiency depends on the line voltage. To cut off the leakage current, it is important to provide power to the circuit. The built-in amplifier is intended for this. These devices are less reliable in operation. If a zero break occurs in the network, then the RCD does not perform its functions. In this case, there is a high likelihood of injury. The current can pass through the human body.
If there is a zero break, the mains voltage is not supplied to the power supply. The phase, due to insulation breakdown, gives off current to the body of the washing machine or other equipment.
Electricity passes through a person who touches a metal surface and travels to the ground. In this case, the protective function is not fulfilled as a result of the design features of the electrical appliance.
There are also electromechanical RCDs on the market. They start to work in the presence of a leakage current. Electrical energy is not used, and the potential is raised on a mechanical spring. If a fault occurs in the insulation, the RCD trips immediately.
Application area
RCDs can be used to protect current leakage in three-phase or single-phase electrical wiring. Experts say that the device must be mounted even on a home network without fail. Especially for the protection of hazardous household appliances.
The current can enter the body in contact with a metal part of the case, through water or other objects. The category of dangerous household appliances includes an electric oven, washing machine, water heater, dishwashing machine. All electrical devices can be damaged. RCD is no exception, therefore, to ensure maximum protection, it is necessary to additionally install a powerful device at the place where the home wiring is entered.
When unforeseen situations arise The RCBO will provide redundancy for protection devices that use separate wiring lines. But they also perform a fire-fighting function. If installed correctly, home wiring is protected from accidental fire. Everyone should know how an RCD works and what is its purpose. This information will help prevent unfortunate consequences for the entire family.
