1. BE5B14SP1 – Electrical machines and electrical apparatus 1
Low voltage protecting apparatus

2. BE5B14SP1 – Electrical machines and electrical apparatus 1
Protection
Against over-current: Fuses, circuit breakers
Fault voltage protection: Residual current circuit breaker
Impulse over-voltage: Surge arresters
(for HV and LV networks protection)

3. BE5B14SP1 – Electrical machines and electrical apparatus 1
Fuses – apparatus operation based on conductor melting in
special adapted chamber (with extinguishing dust)
Melting
characteristics
Dependence
of melting time
as a function of
current passing
through fuse

4. BE5B14SP1– Electrical machines and electrical apparatus 1
Circuit breaker
Time-current switching –off characteristics

5. BE5B14SP1– Electrical machines and electrical apparatus 1
Block diagram of miniature circuit breaker
Current sensor
Switch
Release
Current dependent release (bimetal strip)
Current independent release (electromagnetic)
Switch and extinguishing chamber

6. BE5B14SP1– Electrical machines and electrical apparatus 1
Operational principle of bimetallic current dependent release
Bimetal is heated by passing current
Time delayed slow deformation of bimetallic strip due to warming
Position change of the free end of bimetallic strip released
switching system of circuit breaker
Temperature dependence of bimetal element length.
∆y rod shift released
the key of disconnecting
mechanism
Aluminium
Copper
Silver
Wolfram
Iron
Table of α (alpha) material coefficients

7. BE5B14SP1– Electrical machines and electrical apparatus 1
Cross-section of miniature
circuit breaker
Extuinguishing chamber
Electromagnetic release
Bimetal release

8. BE5B14SP1– Electrical machines and electrical apparatus 1
Cross-section of miniature
circuit breaker
Extuinguishing chamber
Electromagnetic release
Bimetal release

9. BE5B14SP1– Electrical machines and electrical apparatus 1
Cross-section of miniature
circuit breaker
Case, when contacts are
disconnected and electric
arc is spreading into
the extinguishing chamber
Extuinguishing chamber
Electromagnetic release
Bimetal release

10. BE5B14SP1– Electrical machines and electrical apparatus 1
Industrial circut breaker
Electric scheme
of CB internal
connection
Electronic control unit

11. BE5B14SP1– Electrical machines and electrical apparatus
Block diagram of circuit breaker electronic control unit
Adjustment of current dependent
part of disconnecting characteristic
Adjustment of current
Independent part of
disconnecting characteristic

12. BE5B14SP1– Electrical machines and electrical apparatus
Block diagram of circuit breaker with electronic control unit
Disconnecting
relay
A/D
Con
ver
tor
Control
Micro
processor
Current
measuring
transformers
Communi
cation
interface
External
supply
Data bus

13. BE5B14SP1– Electrical machines and electrical apparatus 1
Residual current circuit breaker - RCCB
Disconnecting time /ms/
Disconnecting current I∆/mA/
Residual current versus time disconnecting characteristics of RCCB

14. BE5B14SP1– Electrical machines and electrical apparatus 1
Schema of residual current circuit breaker
Operational principle I2 I3 I4 I1
If I1+I2+I3+I4 = 0… RCCB is connected
If I1+I2+I3+I4 ís not 0… RCCB is disconnected
RCCB
Switching mechanism
Test knob
Differential rele
Sum-transformer
Fault
Load

15. BE5B14SP1– Electrical machines and electrical apparatus 1
Spring
Permannent magnet
Permanent magnet
produces flux which
holds anchor
Anchor
Magnetic flux
produced by
excitation coil
compensates
flux of permanent magnet
and anchor is released
Exitation coil
View of RCCB differential relais

16. BE5B14SP1– Electrical machines and electrical apparatus 1
Application of RCCB in TN-C and TN-S networks

17. BE5B14SP1– Electrical machines and electrical apparatus 1
Over voltage surge arresters

18. BE5B14SP1– Electrical machines and electrical apparatus 1
Cascading of overvoltage limiting devices
1.step- lightning currents arrester
2.step- overvoltage protector
3.step- overvoltage protector
Input
Current-limiting impedance
Output

19. BE5B14SP1– Electrical machines and electrical apparatus 1
The End

20. BE5B14SP1– Electrical machines and electrical apparatus 1

21. BE5B14SP1– Electrical machines and electrical apparatus 1

22. BE5B14SP1– Electrical machines and electrical apparatus 1