Come controllare l'RCD per il funzionamento

According to GOST R 50807 RCD( residual current circuit breaker) is called an operational control device, controlled by a differential( residual) current. The check is made by an ordinary button located on the case of the differential automaton. After 1-5 secondsthe key turns off the device, which indicates the suitability of the RCD.The period of interruption of power is determined by the class of the device, this is literally an instant to the average consumer. Today we learn the method of testing the RCD for tripping.

How to choose and check the RCD

Several classes of residual current circuit breakers have been developed, which complicates the choice of an RCD.Advertise and sell the product, orienting the consumer to the nominal operating current, although the RCD is purchased for an apartment to track a critical case. For housing - short circuit currents and leakage. In accordance with this, the RCD is divided into two types:

• Equipped with automatic switches.
• Differential RCD, without automatic switch, set with additional equipment.

We are familiar with the classification of RCDs, in addition to differential types, there are other types. They are mainly used outside of apartments, shops, garages, factories. In everyday life, they use differential automatic devices - devices with built-in automatic switches - and ordinary RCDs, without automatic switches, that estimate leakage currents( differential currents).The sellers are unfamiliar with the classification, therefore lovers of subtleties are asked to wait for the full story about the connection of the RCD, its varieties.

Marking of residual-current devices

It is important for consumers to understand the structure of the purchased RCD, whether a circuit breaker is provided in it or not. The availability of the machine determines the method of verification. Information is easily clarified by labeling. Let's take the RCD corresponding to GOST 51328. Let's start with the typical symbols:

1. There is necessarily a working current - a load that the RCD maintains constantly. It is important to take into account that starting an engine of household appliances causes a surge in load current for a short period of time. Therefore, we find out whether the device will withstand a jump. On the case, the value of the operating current is 25 or 16 A, installation of a RCD in a circuit with operating parameters below the specified is not practical: the device will periodically operate. The marking is preceded by a physical current symbol: I, less commonly In.
2. The leakage current must be indicated - a key parameter indicating how many amperes it is permissible to drop to earth through the insulation of the device without tripping. According to domestic standards, the magnitude of the leakage current of 30 mA, this UZO put in the bathroom. Denotes the leakage current symbol ΔIn– 0.03 A or 30 mA.
3. The marking of a UZO designed for operation with standard mains parameters is 50 Hz frequency, voltage 220-230 V, does not contain nominal values. If there are figures with the appropriate units of measurement - Hertz( Hz), Volta( V), specify the country of origin from the seller. In the US, the frequency of the industrial network is 60 Hz. UZO of American origin will not be suitable for domestic power grids, sinceThe operating voltage is also different - from 100 to 127 V.

This completes the requirements of GOST for marking. The values ​​of the key parameters - the value of the current response and response time - are not specified. How to check the RCD for compliance, why does GOST omit essential data? The answer is obvious. GOST 51238 is designed for RCDs without overcurrent protection, i.e., for devices without a circuit breaker. In the domestic system of designations, the marking of such RCDs includes DP letters( optional).In practice, wiring diagrams contain a limiting factor - resistors. Standard ground loop resistance of 3 ohms limits the current to 75 A, which is taken into account when assembling the power supply network.

Check RCDs with markings on the built-in control button. It simulates the occurrence of leakage current, the device after pressing the key will turn off the electricity. RCDs with built-in circuit breakers are governed by the standard GOST R 50807. It states that the value of the breaking short-circuit current is indicated in the marking.

The load current( operating current) of the RCD is indicated by the Latin letters In, more often it indicates its value - 16, 25 A or others. The ΔIn marking is indicated to the left - change in load current caused by leakage current or differential current. Regarding the short-circuit current, GOST does not obligate to indicate the value.

The maximum current consumed by appliances( washing machine, convection oven, convection oven), which can withstand the RCD without burning, is given. For example, Im = 1000 A. This is not a short-circuit current causing a trip, but a value characterizing the limit, the limit, the maximum threshold. Ie, UZO does not wait until the current 1000 And kills someone. This limit value does not kill the RCD itself. Disconnection will occur earlier. The parameter corresponds to the rated ability of switching on and switching off the differential current ΔIm. It coincides with Im, becauseon the segment of operability, the RCD is capable of performing the assigned functions - to turn off the power.

Do you need these characteristics if the device shuts off the network during a 30 mA leak? Parameters describe the emergency mode. Suppose there was a short circuit on the sewer. Locked while power was off. With a sharp voltage supply, an avalanche-like increase in current occurs, and it should not exceed 1000 A - the RCD will burn. The standard resistance of the ground loop is 3-5 ohms, if it is good, or 10-15 ohms, if it is bad. Therefore, the current will definitely not exceed 220/3 = 73.3 A. The manufacturer is insured against malfunctions and creates a reserve of electrical strength directly to the RCD.

The true value of the operation current is not indicated, they use the operational schedules of the RCD operation. They reveal two important points:

1. RCDs are classified according to the nature of the working currents. There are three groups: AC, B and A. Belonging to the group indicated at the end of the alphanumeric designation given after the manufacturer's logo. Symbols follow the dash following the RCD code. Information for testing of the RCD is secondary, do not test the device without a clear understanding of the principles of operation. The speaker comes from the English alternating current( alternating current).RCDs labeled with ACs are triggered when an alternating current appears or gradually increases. For DC voltage circuits, the AC device is not suitable. Concerning short circuit - it is described by a group of parameters that are not given in the RCD labeling related to the circuit breakers.
2. The parameters of the short-circuit currents depend on the type of the release. They are characterized by a response time and a current value. If the rating is 1.5 times higher, the circuit breaker will continue to work for an hour or two. Characterize the processes of graphics, called the time-current zone. They determine the response interval at a certain current. For foreign circuit breakers, the type of trip unit is marked in Latin from A and on. Houses recommend using B and C. Devices do not bear a type of trip, use tables III and IV of GOST for the selection of RCDs. However, this is background information; it is much more important to understand whether overcurrent protection is built in or not. In the latter case, before switching to the circuit, calculate the possible modes.

How to check the RCD

The information required for the verification is taken from state( international) standards, the lion's share of it is indicated on the body:

1. RCD type - with or without overcurrent protection to eliminate connection errors. At the second class of devices we look at the rated conditional short-circuit current Inc. Before connecting RCDs and automatons, inspect the enclosure. The fuse icon in the diagram( see figure) implies the amount of current melting the thread. Behind it are indicated in the rectangular frame of the number 4000. .. 6000 - Inc RCD, i.e., the limiting current maintained by the device until the fuse blows out. Similar marking is applied to RCDs without built-in overcurrent protection.
2. Operating nominal current helps with breakdown of the apartment mains into circuits. Parameter rather operational. The operating voltage is not indicated if it is 220 V.
3. The leakage current is measured in an accessible way: the light bulb is switched on in parallel with the resistance U / I = 220 / 0.03 = 7.3 kΩ.The resistance is specifically taken less than the exact calculated one in order to lower the response threshold. A current of about 30 mA will flow through the resistor to the ground, i.e. The leak test required for testing will appear. The device built-in self-control device is triggered. Pay attention that the voltage in the outlet is sometimes different from 220, and adjust the value of the resistor. The length of the ground wire is not taken into account.
4. Short-circuit currents( 1000 A!) Do not check: RCD burns out. To achieve such values ​​in the apartment is almost impossible, to disable the new UZO is not necessary.

The description of the devices also contains the concept of “number of response cycles”, which characterizes the number of emergency shutdowns for which the circuit and design of the device is designed.

We hope that readers, having read the article, will correctly select the RCD for the apartment and check the device in the required volume.