 |
Current device RCD.
At the moment, the RCD has successfully installed in the newly irreducible installations. But the installation and use of RCD and to date raises questions, as the subscribers and workers engaged in installation of electrical installations.
So what is the RCD?
Residual current device (RCD), respond to the differential current, along with overcurrent protection devices, refer to additional forms of protection from destruction by indirect contacts provided by the automatic power-off.
In contrast to the protection against overcurrent RCD is the only way to protect people from electrocution at low current circuit, reducing isolation, not efficient enough. Overcurrent protection (in the application of protective vanishing) protects a person with indirect contacts - by turning off circuit breakers or fuses damaged section of the circuit under short-circuit to ground. , обеспечивающим защиту человека от поражения электрическим током при прямом прикосновении к одной из токоведущих частей. Of all the known elektrozaschitnyh of the RCD is the only one that protects people from electric shock by direct contact with one of the live parts. The same RCD is an excellent protection against damage insulation, wiring and electrical faults are considered to be the main cause of fires and fires that occur in electrical systems.
A bit of history.
For the first time in 1937, the company Schutzapparategesellschaft Paris & Co. produced a first active device based on a differential transformer and a polarized relay, which had sensitivity of 0.01 A and speed of 0.1 seconds. In the same year with the help of volunteers - an employee of the company were conducted full scale testing RCD. In 1960-1970. worldwide, primarily in Western Europe, Japan, the U.S. began active implementation of the RCD in general practice. Currently, hundreds of millions of RCD successfully, as evidenced by official statistics, protect lives and property of citizens of France, Germany, Austria, Australia and other countries from electrocution and fires.
The principle of the RCD.
RCD - Quick-protective agent, responsive to the differential current in conductors transmitting power to the electrical installation to be protected. RCD effect based on the work of a differential transformer toka.Summarny magnetic flux in the core - F, is proportional to the difference between the currents in the conductors, which are the primary windings of current transformers, IL and IN, induces in the secondary winding of the transformer emf, which is under the influence of the secondary circuit flows a current I proportional to the difference between the primary current. This current and triggers the release mechanism. In normal operation, the net magnetic flux is zero, the current in the secondary winding of the differential transformer is also zero. When you touch a person to open or conductive parts to the body for power consumers, which occurred at the breakdown of insulation on the phase conductors through the RCD than the load current flows an additional current - current leakage, which is for the current transformer differential (difference). The inequality of currents in the primary windings is unbalanced magnetic flux and, consequently, the occurrence of the secondary coil of the transformed differential current. If the current exceeds a preset value of a threshold gate trigger body, triggered the latest and the effect on the actuator. To control serviceability (serviceability) provides RCD circuit test ("Test" button), working through the artificial creation of a differential current switch-off.
Major errors during installation the RCD.
The most common error when installing the RCD is connected to the RCD load in the circuit where there is a connection of neutral conductor N with exposed conductive parts of electrical systems or connection to the protective earth conductor PE. In this case, the probability of "voluntary" response RCD is very high. You may see the following error: connection to the load neutral conductor to the RCD, a connection to the load neutral conductor of another RCD, the jumper between the neutral conductor of various RCD, a connection on the load side conductors PE and N at the outlet.
Example include the RCD.
Governing regulations.
- Rules for Electrical Univ. 7th.
- Standard 12.4.155-85. "Residual current device. Classification. General Requirements"
- GOST 50807-95 (IEC 755-83). "Devices protective, controlled by the differential (residual) current"
- GOST 50571.3-94 (IEC 364-4-41-92). "Electrical installations of buildings. Requirements for safety. Protection against electric shock."
- GOST 50571.11-96 (IEC 364-7-701-84). "Electrical installations of buildings. Chapter 7. Requirements for special installations. Section 701. Bathrooms and shower rooms."
- GOST 50571.15-97 (IEC 364-5-52-93). Part 5. "Selection and installation of electrical equipment. Chapter 52. Wiring."
- GOST R 50 669-94. "Electricity and electrical cell (inventory) of buildings made of metal or a metal frame for street trading and public services. Specifications."
And more ...
-New game! 
|