Download AVOP-ELEKTRO-SKA-010

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
current
Residual (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.
Test buttons
For one-phase circuits
For three-phase circuits
(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
One-phase appliance
With null
Without null
RCDs in TT, IT network
TT Network
IT Network
L1
L1





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
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http://www.jtlelektro.cz
www.wikipedia.cz