Today it is very important to ensure the safe functioning of the electrical network and household appliances. This will protect expensive equipment from premature breakdowns. Special protective RCD devices can cope with this task. An indicator of the quality of their work is the operation of automation. As practice shows, sometimes it works for no apparent reason, as a result of which there is a complete de-energization of the electricity in the room. And many owners are wondering why the RCD machine works.
What is this?
A residual current device (RCD) is a special device that provides a protective function to a person from the effects of currents, and also reduces the risk of wiring fires during short circuits by stopping the current supply to the wiring at certain points. It can be used in combination with other protective devices, as well as separately from them. There are several options for why the RCD is triggered. This is an instant reaction to factors such as:
- current leakage;
- voltage overload;
- short circuit in wiring system.
Appearance of the electrical protective unit
The geometric shape of the RCD is almost identical to the shape of the circuit breaker. The case is equipped with a locking lever, a "T" button and a printed marking. Small holes are formed in the upper and lower parts of it. These holes contain the terminals. The product is available in two sizes and differs in the number of holes, there can be 2 or 4 of them.
The main function of the RCD
The main function of the device is to compare certain indicators of the input and output of the current of the electrical circuit. At the time of the formation of a leak, a natural response occurs, which is the reason why the RCD worked. It is this action that indicates that a current leakage has occurred. It is performed by a differential transformer equipped with a core with several windings arranged in the inner plane of the protective product:
- Two wires, having identical indicators of its diameter and turns, are conductors "phase" and "zero". Their winding is made in a certain direction, which contributes to the meeting of electromagnetic flows created in the process of current flow.
- One winding performs the control function. howas soon as a current appears in the winding, its passage is turned off. The electromechanical relay, equipped in the inner plane of the protective unit, is directly connected to this winding.
Distinctive characteristics of RCDs
A distinctive feature is the type of current operated:
- A - sinusoidal variable and pulsating constant;
- AC - sinusoidal variable;
- B - constant, pulsating constant and sinusoidal variable.
And also:
- Rated load current. This parameter indicates the allowable amount of current passing through the protective unit. Standard amp scale values: 125 A, 100 A, 80 A, 63 A, 40 A, 25 A, 16 A.
- Rated differential current. The differential current is a leakage current. Its standard milliamp scale is: 500mA, 300mA, 100mA, 30mA, 10mA, 6mA.
Features of the choice of RCD
Based on the fact that the main function of the unit is to protect a person from electric shock, when choosing it, it is necessary to take into account the rating of the differential current. This indicator should not exceed 30 mA.
For spaces with high humidity, such as a bathroom, shower, bathroom, so that there are no questions why the RCD worked, the best option would be a device with a rating of 10 mA.
For socket groups and lighting networks in homes, experts recommend using a device with a parameter of 30mA.
Protective devices that perform a fire function will have a differential current value: 100 mA, 300 mA, 500 mA. They perform the task of preventing a fire from a leak in the wiring. These types are strictly forbidden to be used for socket systems, since a human being struck by a differential current of 100 mA will lead to death.
Location and external factors
Quality performance is directly related to location and weather conditions such as humidity and temperature changes. These factors can lead to a failure of the operating mode, which will be the reason why the RCD trips for no reason. Installation in a panel located outside or in an unheated space is likely to result in an abnormal response. Sudden temperature changes can lead to the formation of condensate in its internal part, as a result of which the automation will react. It should also be borne in mind that microcircuits do not withstand frost. The best arrangement would be a dry, warm room.
Reasons for tripping RCD
Leakage currents can occur due to various circumstances. Therefore, the most important thing in solving this problem, why the RCD is triggered, is their correct definition. Consider some options:
- Wiring. If the wiring in the house is not new, but has served for a sufficiently long period, then a leak may occur. Electrical tape often acts as the culprit, since its base may lose its elasticity. It will lead toto the formation of small cracks, which will be the "path" of small leaks. If the wiring was carried out recently, then you should check the connection points of the conductors, perhaps they were made of poor quality connection. Damage to the insulation of the conductors, for example, during repair work, should not be ruled out.
- Household electrical appliances. In the process of using electrical units, very often there are problems with structural violations of the insulation of the cord that provides connection to the mains, as well as breakdown of internal parts.
- Quality of electrical work. This is the most common reason why the RCD does not work with zero leakage. Poor connection of conductors in the electrical network system, which includes the junction box, switches, sockets, as well as in protective devices.
- Increased humidity level. When carrying out repairs near the location of the wiring using liquid mixtures, the protection system may also trip.
The response of the device to any of the above reasons will be proof of its serviceability, as well as the correct and high-quality connection to the electrical system.
Determining the causes of triggering is not an easy task, but still doable if you follow the recommendations of experts and follow the proposed search algorithm.
Testing the RCD for serviceability
To exclude unsuitability, you need to make sure that the protection connection process is carried out correctly. Conduct testingpossible by performing some operations:
- Disable machine. Performing this action will eliminate the impact on the RCD of all objects connected to it.
- Disconnect outgoing conductors by removing them from the pre-loosened terminal.
- Check that the stop lever is working properly. Set it to the "on" position and lightly tap on the case. A spontaneous change in the position of the mechanism at the time of the option indicates a failure of the lever, which means that the RCD is not suitable for further operation.
- Turn on the machine (the locking mechanism must be in working order). Automation should not react, since the conductors are disconnected at the output, but its response will be the basis for replacing the device.
- Performing testing by pressing the "T" button. A he althy unit will respond with an immediate shutdown.
Why does the RCD work without load
The sequence of actions is as follows:
- Turn off household appliances and lighting.
- Connect the wires in the terminal, after turning off the machine.
- Turn on auto.
Monitor device functionality for at least 15 minutes. If it works in normal mode and the automation does not work, then there is no problem in the wiring. If it works, then there is a leak. It is possible that this will not be a single leak, so you should carefully approach this task and eliminateproblem.
It is strictly forbidden to connect ground wires and "zero". These reasons can lead to abnormal operation of automation.
Electrical appliances and their participation in RCD operation
At this stage, it is necessary to connect each individual electrical appliance (appliances, table lamps and fixtures) to the network. This will allow you to find out why the RCD is triggered when a particular device is turned on.
Equipment should be plugged into an outlet without the use of additional adapters (tee, carrying). This rule should be followed, as sometimes the wires of the adapters are the culprits of the leak. It is necessary to check all devices, perhaps the leak occurs not in one, but in several.
RCD operation when the washing machine is turned on
Very often, when the washing unit is connected to the power supply, the current is turned off. In this case, you should first make sure that it is the machine that is the cause of the operation. It is necessary to plug into the outlet where the machine is turned on, another device. Its amount of energy consumed must match the machine. If the machine does not respond, then the problem is in the previously connected device. There may be several reasons why the RCD is triggered when the washing machine is turned on:
- wear on cord or plug;
- presence of condensation on internal conductors;
- short circuit in the electric heater (heater);
- failure of the "network filter";
- short circuit of the motor, control board orstart buttons.
Why does the RCD work when the water heater is turned on
The activation of the protection at the moment of turning on this device gives a warning signal about malfunctions in its operation. Water heating is carried out using an electric heater, consisting of tubes with a spiral built into them. Prolonged use of the boiler may lead to insulation failure of the conductors, as well as due to the accumulation of scale on the tubes, which leads to damage to their surface. Small cracks appear on it through which water penetrates into the middle of the tube. Contact of water with a coil will cause a short circuit of the current. In most cases, it is the failure of the heater that leads to the operation of the RCD. However, this is not the only reason.
Other possible reasons why the RCD on the water heater works:
- Wrong choice of boiler power;
- violation of insulation of internal conductors;
- wrong electrical connection;
- connecting to the power supply of several household appliances.
To avoid overloading the electrical network, it is necessary to equip separate sockets for connecting a washing machine, water heater, dishwasher, microwave oven.
The implementation of a full range of checks of the probable reasons why the RCD is triggered will provide an opportunity to assess the level of the state of the electrical network of house construction.
