tutorial: mechanic - electrician topic: fundamentals of electrical engineering the 2nd. year, rcd...
TRANSCRIPT
Tutorial: Mechanic - electrician Topic: Fundamentals of electrical engineering
the 2nd. year, RCD
Prepared by : Škarka Miloš
Projekt Anglicky v odborných předmětech, CZ.1.07/1.3.09/04.0002
je spolufinancován Evropským sociálním fondem a státním rozpočtem
České republiky.
Residual current device is an electrical device used for increased protection against injury caused by an electric current. It can‘t be used for basic protection – by automatic disconnection. Working wires are conducted through RCD, protective conductor mustn't be conducted through this device.It is used in environments with higher danger of injuries caused by an electric current.It‘s main parameters are:Nominal currentResidual (differential) current Selectivity
In normal conditions the vector sum of currents in working conductors equals null. In the secondary winding of the transformer no voltage is induced. In case of a current leak from the phase conductor to the ground, the voltage emerges in the secondary transformer winding, the current gets through the coil of the electro magnet and a malfunction is quickly disconnected from the rest of the electric network.
For one-phase circuits For three-phase circuits
Test buttons
(1) Input power terminals(2) Output load terminals(3) Reset button(4) Contacts (the second one is for relay)(5) Relay equipment
(6) Differential transformer(7) Control valve(8) Test button(9) Test conductor (orange)
RCD connection in TNC-S network
With null Without null
One-phase appliance
RCDs in TT, IT network
L1 L1 IT Network TT Network
Principle of RCD Which conductors have to be conducted
through RCD? What is a residual current? When do you have to use RCD? Draw the connection of RCD in TN network
What do numbers in picture 1 connote?
Picture 1
• http://www.jtlelektro.cz• www.wikipedia.cz