Device (RCD) - a simple and inexpensive device, saving of electric shock and fire.
RCD quickly disconnects the electricity at any leaks, whether poor insulation, the breakdown of the housing of the appliance or a human touch to the phase wire.
The operating principle of an RCD is easy - it compares the currents of the phase and neutral conductor. Once they are not equal, the RCD breaks the circuit.
If a person touches the phase current begins to flow through the body into the ground and disconnects electricity RCD, the risk of death by electric shock is significantly decreased.
In the case of insulation failure (for example inside a wall or water Gulf) there is the same - a current starts to flow not only in the neutral wire, but in the ground, the current value of the phase and neutral wire cease to be equal and RCD disabled.
For proper operation of the RCD it is important that the electrical enclosure are grounded. For example, if the inside of the washing machine breakdown happens on a grounded housing, the RCD immediately turn off the electricity, if the housing is not grounded, it may happen that the RCD will not turn off and on the network would be the case voltage.
It is important to understand that the RCD does not disconnect the circuit when exceeding the rated current, and does not replace normal switch machine. Available in combined devices - Emergency circuit breakers, which combine the RCD and the machine, but they are quite expensive and always better to put a separate RCD and automatic. Benefits Emergency circuit breakers - less connections and space saving in the panel. Single-phase RCDs usually takes two places and another place will be automatic.
With terminology in Russia there was a mess. RCDs are often referred to as residual current circuit breakers (RCCB) or residual current devices and Emergency circuit breakers - automatic differential current circuit breakers (RCBOs) or differential current protection devices overcurrent.
Any Emergency circuit breakers or RCD has a TEST button (T), which allows at any time to check the operation of the device - when it is pressed to happen off the main circuit breaker.
There are various types of RCDs (A, B, C and the coincident), characterized by differential currents type and rate of reaction. More information can be found Wikipedia. In household typically used RCD type A or AC.
The two main parameters of RCD - the maximum current and the operating current. In household typically used RCD tripping current of 30 mA (0.03 A), and the maximum current is chosen the same as or greater than the rated current or counter input automaton.
When finances allow and there is a place in the shield is better to install several RCD on different groups of consumers. In this case, triggered one RCD will not be de-energized all consumers.
In new buildings always put two RCD - one fire on the landing with operating current of 300 mA, a second primary in the flat panel with operating current of 30 mA.
When using an RCD has a funny side effect - the closure of zero and earth RCD disabled. It would seem there and there is no tension, but it is simple - as soon as the zero and earth are closed, some of the current devices, which are now working, begins to flow into the ground through the point circuit and the phase currents and the ground are no longer equal.
Single-pole RCD with a maximum current of 40 A is now worth about 1,000 rubles. If you are at home or at the cottage is still not worth the RCD, it is recommended to install it, because the device makes use of electricity is much safer.
© 2015 Alex Nadozhin