This document summarizes a seminar presentation on circuit breakers. It discusses the operating principles of conventional circuit breaker designs and the need for advancements in technology. Motor drive-based HVDC circuit breakers and solid state device-based DC circuit breakers are presented as promising technologies. Intelligent circuit breakers are also discussed as a way to increase grid stability and integrate distributed generation without replacing existing infrastructure. The document concludes that further research is needed in fast mechanical switches, optimizing existing CB schemes, and developing pure semiconductor switches.

1. A SEMINAR PRESNTAION ON
SUBMITTED BY:
PUNEET SRIVASTAVA
DEPARTMENT OF ELECTICAL ENGINEERING
B. Tech III Year

2. CONTENTS
 What is a circuit breaker?
 Circuit breakers vs Isolators
 Operating principles of circuit breakers
 Conventional designs
 Need of advancements in circuit breaker technology
 Motor drive based HVDC circuit breakers
 Solid state devices based DC circuit breakers
 Intelligent circuit breakers
 Concluding remarks

3. WHAT IS A CIRCUIT BREAKER?
 Circuit breakers are switching devices, capable of making, carrying and breaking currents
under normal and abnormal circuit conditions.
OR
 Circuit breaker is a piece of equipment which can
 Break the circuit automatically under fault conditions
 Make or brake a circuit either manually or by remote control under normal
conditions

4. CIRCUIT BREAKERS VS ISOLATORS
 Isolator(line isolators) is an off-load device while, circuit breaker is an on-load device.
 Isolator is a switch operated manually, which separate the circuit from the power
main and discharges the trapped charges in the circuit
 Isolators operate in power off mode while circuit breakers usually in fault conditions

5. OPERATING PRINCIPLE AND ARCING
 Essentially contains two electrodes which remains intact under normal conditions
 Automatically opens when system comes under faulty conditions
ARC PHENOMENON
 An arc struck when contacts are separated
 The arc provides a low resistance path to
the current thus it remains uninterrupted

6. ARCING INTERUPTION
 HIGH RESISTANCE METHOD
 Arc resistance is made to increase with time
 Current is reduced to below the minimum level
necessary for arcing
 High energy released; thus merely used
 LOW RESISTANCE METHOD
 At current zero the dielectric strength of
medium is increased
 The current fails to regain, thus the doesn't
persists

7. CONVENTIONAL DESIGNS
OIL CIRCUIT BREAKERS
AIR BLAST CIRCUIT BREAKERS
SULPHUR HEXA FLOURIDE CIRCUIT BREAKERS
VACCUM CIRCIT BREAKERS

8. NEED OF FURTHER STUDIES
 USE OF HVDC INSTEAD OF HVAC
DC breakers have to interrupt short-circuit currents very quickly and need to
dissipate the large amount of energy which is stored in the inductances in the
system.
Absence of natural current zero crossing in HVDC
 USE OF VOLTAGE SOURCE CONVERTERS(VSCs) INSTEAD OF CURRRENT SOURCE
CONVERTERS(CSCs)

9. MOTOR DRIVE BASED CIRCUIT
BREAKER
 Present market, there are four types of operating mechanism widely used:
1)electromagnetic 2)spring 3) pneumatic 4) hydraulic
 PMSM are used for rapid torque response and high-performance controlled operation
 It provides conditions for implementing intelligent opening and closing operation for
HVCB
 The speed, position, current, and voltage sensors are installed in the control system to
obtain continuous self testing and monitoring.
 Experimental setup for-126-kV HVDC and a 30-kW PMSM

10. WORKING OPERATION
 The motor-drive mechanism is mainly composed
of the ac/dc power supply, energy buffer
capacitors, converter, and control unit and motor
 The capacitors are the energy buffering units
which provides the energy which required during
the operation of a CB.
 It uses a three phase, 2/2 PMSM for rapid torque
response and high-performance operation
 The stator current is measured by hall sensors.
Motor speed and rotor position are measured by
the optical encoder installed in the shaft

11. ELECTRODES SEPARATION
 A Permanent Magnet Synchronous Motor(PMSM)to drive the
HVCB
 Predesigned operating characteristic automatically according to
the monitored fault current and voltage to achieve
 In the opening operation driven by the motor-drive mechanism,
the crank (8) rotates counterclockwise; pulling the insulating rod
(7) down.
 This quickly drive the moving arc contact (3) downwards
 At the end of the opening operation, the motor applies a
clockwise torque
 on the driving shaft (9) to decelerate the crank (8) rotation. The
moving arc contact (3) speed will smoothly decrease and the
mechanical impact will be limited.

12. SOLID STATE DEVICES BASED
CIRCUIT BREAKERS
 In recent years, a system based on self-commutated voltage-source converters (VSCs)
consisting of IGBTs are applied to many projects
 It has advantage in control characteristics and reduction of ac filters and shunt capacitors
 The VSCs have small impedance in the dc side because their dc capacitor is parallel to the dc
transmission line.
 Under fault condition VSC’s dc capacitor is discharged by way of the fault point, the fault
current rapidly increases
 Gate block operation of the VSC does not interrupt the fault current because the current flows
through the VSC’s reverse conducting diodes during the fault
 Experimental setup-at 300 MW in power and 250 kV in dc voltage,

13. WORKING
 A voltage source Vdc supplies dc power to a
resistive load by way of inductance Ldc. Ldc is the
overall inductance in the dc circuit
 The blocking voltage of the breaker is increased by
connecting many semiconductor devices(Q) in
series
 Q remains at ON-state during normal condition, and
the current iL flows from the source to the load. Q is
turned off
 Surge voltage across Q is suppressed to the
clamping voltage of the varistor Rv.
 The clamping diode voltage is larger than Vdc, and
it is assumed as Vdc + VMARGIN.

14. INTELLIGENT CIRCUIT BREAKERS
 Patented by SCHNIDER ELECTRIC™ in 2008
 For the multi level generations the grids are
now using bidirectional flow of power
 For today’s hierarchical distribution grid
anticipation of the limitations the bidirectional
power flow and the limited information flow.
 All decentralized generation will increase the
short-circuit power in the grid segment
 Maximum switching current might not be
reached due to the electromagnetic forces to
the arc.

15.  The iCB will deliver a unique solution to
increase grid stability without scrapping
existing infrastructure
 In case of a failure, the local breaker will
identify this and will decide upon its
capability to handle the failure current
 If upstream fault is within limits CB trips the
power flow if downstream it O-C-O
 If not in limit CB remains on
 If it remains on increase of short circuit
power is detected and the bus is disconnects
the faulted local generation
 Isc for breaker A will be now on a level where
the failed line can be cleared.
WORKING

16. CONCLUSION
Several technological areas where research and development is needed in order to improve
or enable HVDC CBs. These areas are summarized in the list below as follows.
 Fast mechanical switches or disconnectors with high recovery voltage withstand and
low on-state-losses. Ideally, these switches have sufficient arcing voltage for fast
commutation.
 Optimization of the existing basic HVDC CB scheme by optimizing the size of
elements, such as capacitors, inductors, varistors, or charging units. The main goal is a
reduction in size, interruption time, and costs.
 Pure semiconductor switch with minimal on-state losses. Use of new wide bandgap
power semiconductor devices

17. REFRENCES
 Christian M. Franck,” HVDC Circuit Breakers: A Review Identifying Future Research Needs”,
IEEE transactions on power delivery, vol. 26, no. 2, april 2011
 Yulong Huang, Jingjun Wang, Wenchao Zhang, Mohmmad Al-Dweikat, Dawei Li, Tao Yang,
and Shengnan Shao,” A Motor-Drive-Based Operating Mechanism for High-Voltage Circuit
Breaker”, IEEE transactions on power delivery,vol.28,no.4,october2013
 Kenichiro Sano, Member, IEEE, and Masahiro Takasaki,”A Surgeless Solid-State DC Circuit
Breaker for Voltage-Source-Converter-Based HVDC Systems” IEEE transactions on industry
applications, vol. 50, no. 4, july/august 2014
 Uwe Kaltenborn, Michael Karstens, Pavel Novak, Raimund Summer Schneider Electric –
Germany,” Local intelligent circuit breakers A new concept for the refurbishment of
existing distribution networks”