Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Programmes to control the short circuit arc operat...

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Programmes to control the short circuit arc operat...: Programmes to control the short circuit Arc operation These programmes are to control the operation of the experimental equipment, analy...

Programmes to control the short circuit arc operation

Programmes to control the short circuit Arc operation

These programmes are to control the operation of the experimental equipment,
analysing the experimental results and make a series of the arc images movies to
observe the movement of the arc root from contact region into the arc chamber.
Description of the programmes as follows:

This program is installed to run the test sequences operation. This
program is used to control the sequences of the Flexible Test Apparatus (FTA), Arc
Imaging System (AIS), the capacitor discharge system (CDS) and the digital storage
oscilloscope (DSO).
The software computer program Flexgav4.bas starts to run, the delay contact time is
entered as required, the capacitor bank is then charged to the desired voltage, the
apparatus operate sequentially.
The solenoid is fired and the test data is recorded in the RAM of the Arc Imaging
System (AIS) as previously described [9,10,11,12,66]. Simultaneously the short
circuit current and the short circuit voltage are displayed on the digital storage
oscilloscope (DSO).
The experimental result is transferred from the memory of the digital storage
oscilloscope (DSO) and from the Arc Imaging System (AIS) to the hard disk in the
personal computer (PC).
When this program is initiated, the Digital Storage Oscilloscope (DSO) will reset its
system. A symbol READY status for recording a new test data acquisition is shown.
A delay contact time (tcod) is entered into the PC. After that the apparatus will start to
charge the capacitor bank until the required voltage is reached.

Ref: Arc Control in Circuit Breakers: Low Contact Velocity

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Short circuit current at 500A

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Short circuit current at 500A: Short circuit current at 500A For short circuit current level 500A, both anode and cathode root contact delay longer in the contact reg...

Short circuit current at 500A

Short circuit current at 500A

For short circuit current level 500A, both
anode and cathode root contact delay longer in the contact region before it moves
slowly off from the contact region towards into the arc chamber. At the short circuit
current level 2000A, the arc root moves from the contact region faster than that of
1400A and 500A.

Ref: Slow Contact Opening Circuit Breakers

 

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Electron energy when using Ag/C step contact mater...

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Electron energy when using Ag/C step contact mater...: Electron energy when using Ag/C step contact material The relationship between electron energy and chemical elements when using Ag/C...

Electron energy when using Ag/C step contact material

Electron energy when using Ag/C step contact material

The relationship between electron energy and chemical elements
when using Ag/C step contact material. There are 25 chemical elements when using
Ag/C step contact material. At the wavelength 500 nm, it shows the maximum
electron energy at 3.98x10-37 J from the chemical elements O II, O, IV, Ti VIII, Al
IV and N III.
The average energy for all chemical elements when using the Ag/C step contact
material is about 3.14x10-37 J. The lowest energy is at the wavelength 821 nm for
chemical elements N I, O I and O II about 2.42x10-37 J.

Ref: Arc Control in Circuit Breakers: Low Contact Velocity

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Magnetic forces in the contact area

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Magnetic forces in the contact area: Magnetic forces in the contact area The conductors in circuit breaker and the arc are assumed to be threadlike. The anode is set on the...

Magnetic forces in the contact area

Magnetic forces in the contact area

The conductors in circuit breaker and the arc are assumed to be threadlike. The anode is
set on the moving contact and the cathode is on the fixed contact. The magnetic flux
density (B) is calculated by using a function of current and contact gap.
The experimental results provide the data of the arc current and the contact gap. The
magnetic flux density (B) is obtained from the magnetic force modeling. The
magnetic forces on arc root are calculated by using the relationship of the arc current,
contact gap and magnetic flux density (B).
At the point at which the arc root moves from contact region with contact opening
velocity 1-10 m/s, the contact gap is between 1.57 to 6 mm. Thus, the arc motion for
a contact gap less than 1 cm can be explained in terms of magnetic field

Ref: Arc Control in Circuit Breakers: Low Contact Velocity

Slow Contact Opening Circuit Breakers

Piezoelectrics in Circuit Breakers: Design and Test

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Energy in High and Low speed

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Energy in High and Low speed: Energy in High and Low speed There are 20 chemical elements when the contact opening velocity 10 m/s and 19 chemical elements when the con...

Energy in High and Low speed

Energy in High and Low speed

There are 20 chemical elements when the contact opening velocity 10 m/s and 19
chemical elements when the contact opening velocity 1 m/s. The electron energy for
each chemical elements decrease as the wavelength increases. The maximum energy
when contact opening velocity at 10 m/s, is about 0.79x10-37 J higher than that
contact opening velocity 1 m/s. Both have the same minimum energy at 2.42x10-37 J
of the chemical element N I, O I and O II at the wavelength 821-824 nm. The average
energy when the contact opening velocity 10 m/s is higher than the contact opening
velocity 1m/s about 0.31x10-37 J.

Reference:

 

Arc Control in Circuit Breakers: Low Contact Velocity 

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Force in the Arc The total forces integrated alo...

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers:  Force in the Arc
The total forces integrated alo...:  Force in the Arc The total forces integrated along the arc length and contact opening velocities are shown in Figure 7.4. The results sh...

 Force in the Arc

The total forces integrated along the arc length and contact opening
velocities are shown in Figure 7.4. The results show no simple trend with contact
opening velocity. However, the data are compatible with an approximately constant
total force.
The results of the magnetic forces modeling here are lower than the modeling results
of Paul [11] who considered the magnetic driving force in the contact region from the
magnetic field from the conductors and steel plates in the side walls. The magnetic
flux density (B) was 31 mT/kA for the conductors in the air with a gap of 10 mm.
Thus, at an arc current 2000 A, the magnetic forces was about 1.24 N.
The arc chamber geometry is considered. The magnetic flux density calculation here
is considered at the point that the arc root moves from the contact region with contact
opening velocities.

 

Reference:Arc Control in Circuit Breakers: Low Contact Velocity

 

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Anode and Cathode root in Circuit Breakers

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Anode and Cathode root in Circuit Breakers: Anode and Cathode root in Circuit Breakers The anode and cathode root displacement are shown in Figure 4.21. The results show that when...

Anode and Cathode root in Circuit Breakers

Anode and Cathode root in Circuit Breakers

The anode and cathode root displacement are shown in Figure 4.21. The results show
that when the pressure starts to rise up, both anode and cathode root still stay in the
contact region. At the period of 1800 μs, the second pressure rises up.
This is coincident with the point that the cathode root moves off from the fixed
contact. When the anode root moves from the contact region at the period of 2600 μs,
the pressure drops down shapely.
At contact opening velocity of 10 m/s (see Figure 4.16), the pressure rises earlier than
that of 1 m/s. The maximum pressure when the contact opening velocity of 1 m/s is
double that of 10 m/s. The arc root contact time at contact opening velocity of 1 m/s
is longer than that of 10 m/s. The period the arc root is in the arc chamber at contact
opening velocity of 1 m/s is shorter than that of 10 m/s.

Reference:

Arc Control in Circuit Breakers: Low Contact Velocity Paperback – 1 Jan 2017 by Dr Kesorn Pechrach PhD (Author)

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: The Energy and Mass of Ag/C and Cu in Protection d...

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: The Energy and Mass of Ag/C and Cu in Protection d...: The Energy and Mass of Ag/C and Cu in Protection devices The Ag/C step   contact material   shows the maximum electron energy  ...

The Energy and Mass of Ag/C and Cu in Protection devices

The Energy and Mass of Ag/C and Cu in Protection devices

The Ag/C step contact material shows the maximum electron energy less than the Cu Punch contact material. However, there is only one chemical element, O II appears in both Ag/C step and Cu Punch contact material. Both contact Material Ag/C step and Cu punch have the same lowest energy at the wavelength 821 nm for chemical elements N I, O I and O II.

The Mass of the chemical elements Ag I and Cu II is higher than other chemical elements about 4 times in the Ag/C step contact material. The maximum Mass when using the Cu Punch contact material is the chemical element Cu II at the wavelength 776 nm. This confirms that the chemical element Ag I and Cu II come from the contact material. Both the Ag/C step contact material  and Cu Punch contact material show the minimum Mass is the chemical element H. The average Mass of Ag/C contact material is 0.026g higher than Cu Punch contact material.

The highest temperature rise of Ag/C step contact material belongs to chemical element N III at the wavelength 500 nm. The maximum temperature rise for the Cu punch contact material is the chemical elements NII at the wavelength 428 nm.  The maximum temperature rise for the Cu punch contact material is higher than the Ag/C step contact material. Both Ag/C step contact material and Cu Punch contact material have the same minimum temperature rise and the same chemical element Cu II, at the wavelength 776 nm. The average temperature rise for the Ag/C contact material is lower than the Cu Punch contact material about 0.25x10^-33 K. 

Reference:  Arc Control in Circuit Breakers: Low Contact Velocity Paperback – January 1, 2017 by Dr Kesorn Pechrach PhD (Author)

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Chemical Elements in Short Circuit Breakers

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: Chemical Elements in Short Circuit Breakers: Chemical Elements in Short Circuit Breakers The maximum energy when contact opening velocity at 10 m/s is higher than the contact ...

Chemical Elements in Short Circuit Breakers

Chemical Elements in Short Circuit Breakers

The maximum energy when contact opening velocity at 10 m/s is higher than the
contact opening velocity 1 m/s. However, they have the same minimum energy and
the same chemical element N I, O I and O II. The average energy when the contact
opening velocity 10 m/s is slightly higher than the contact opening velocity 1m/s.
Both contact opening velocity of 1 m/s and 10 m/s has the same minimum and
maximum Mass. The maximum Mass, when the contact opening velocity 10 and 1
m/s is the chemical element Ag I. The minimum Mass is the chemical element H. The
Mass average when the contact opening velocity 10 m/s is 0.003g higher than the
contact opening velocity 1 m/s.
The maximum temperature rise when the contact opening velocity 10 m/s, the
chemical element N II, is higher than the contact opening velocity 1m/s the chemical
element N V. The minimum temperature rise of the contact opening velocity 10 m/s,
is the chemical element Cu II, is not significantly different from the minimum
temperature rise of the contact opening velocity 1 m/s.

Reference:  Arc Control in Circuit Breakers: Low Contact Velocity Paperback – January 1, 2017 by Dr Kesorn Pechrach PhD (Author)

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: The Effect of Magnetic Forces on Arc Control

Dr. Kesorn Pechrach Weaver: Arc Control in Circuit Breakers: The Effect of Magnetic Forces on Arc Control:  The Effect of Magnetic Forces on arc control The magnetic forces on the arc root increase as the arc current increases. The contac...

The Effect of Magnetic Forces on Arc Control

 The Effect of Magnetic Forces on arc control

The magnetic forces on the arc root
increase as the arc current increases. The contact gap has a minimal influence on the
magnetic forces on the arc root. The magnetic forces on the arc root are mainly
dependent on arc current.

The different is the influence of the shapes of the
contacts are modelled. From the experimental results in Section 4.3.1, Chapter 4, the
Ag/C on the moving contact causes a longer delay in the tip of the moving contact.
An Ag/C step and Ag/C flat on the fixed contact are used to compute the magnetic
forces on the arc root, see Figure 3.19, Chapter 3.

The material of the arc runner is Cu and it is 1.0 mm thick. The material of the
contact is Ag/C (95/5 %) and 0.8 mm thick. The anode is on the moving contact and
the cathode is on the fixed contact.
A Silver/Graphite contact pad with a step to the surface of the arc runner is shown in
Figure 5.4. A Silver/Graphite contact pad flushes without a step to the surface of the
arc runner is shown in Figure 5.5.

Reference: Arc Control in Circuit Breakers: Low Contact Velocity Paperback – January 1, 2017 by Dr Kesorn Pechrach PhD (Author)

Variable factors in Arc Control

Variable factors

To investigate the influence of Ag/C contact
materials on the arc root motion from the contact
region, a piece of Ag/C is welded on the fixed and
the moving contact when the anode and cathode
power supply are set in the fixed and moving
contacts.
To inspect the influence of the short circuit current
level on the arc root commutation from the contact
region, three levels of the short circuit current are
expected: 500 A, 1400 A and 2000 A. The Capacitor
Discharge System (CDS) is charged up with
capacitor 47.4 mF, inductor 224 μH and resistance
30 mΩ [2].

Reference: 

Arc Control in Circuit Breakers: Low Contact Velocity

The Theory of Short Circuit Current Electrical Arc

Short circuit current Electrical Arc

The subject of the electrical arc is of interest from the theoretical viewpoint and also
of considerable practical importance. The design of circuit breakers is mainly based
on experience rather than precise science. Empirical formulae can be used to
determine dimensions of certain general types and the breaking capacity rating. There
has been a noticeable lack of co-ordination between theoretical and practical work.
There has been no lack of experimental work on this subject, but the bulk of this
work has referred to problems of a scientific rather than a practical nature.

In circuit breakers, the arc exists in a mixture of air, nitrogen, oxygen and metallic
vapor. Interruption is due to elongation of the arc, which results in cooling, and deionization
by diffusion. Owing to the high temperature of the arc relative to the
surrounding air, the arc is subjected to strong convection currents, which coupled
with the electromagnetic effect of the current loop, causing the arc to move.

An overcurrent is a current flow more than the rated of current of the equipment. This
may result from equipment overload or the failure of a component. This could cause
insulators to fail. In a short circuit current, there is a very high magnitude of
overcurrent from a fault of negligible impedance between conductors having a
difference in potential under normal operating conditions. The conductors and
insulators could melt and vaporise immediately. Additionally, the magnetic forces
from high short circuit current can damage both circuits and circuit breakers [2].

When a short circuit occurs, the current flow through the circuit rises up rapidly and
continues to the peak current of the AC. A natural current zero occurs every 10 ms
for a 50 Hz cycle, if there is no protection circuit. This peak current is called the
Prospective Peak Short circuit current (Ippscc) as shown in Figure 1.1.

Reference: Arc Control in Circuit Breakers: Low Contact Velocity Paperback – 1 Jan 2017 by Dr Kesorn Pechrach PhD (Author)

Background of Arc Control

1.1 Background

In the low and medium voltage range, a circuit interrupting device is used to interrupt
prospective peak short circuit current up to 100,000 A. These devices must have the
ability not only to interrupt load currents, but also to interrupt a short circuit when the
fault current can reach a magnitude many times full load.
The fuse, by comparison with circuit breakers, suffers the disadvantage that
replacement is necessary after operation. The physical size of the fuse and therefore,
its cost, is directly proportional to its current rating. The fuse, being a thermal device,
generates more heat than the current carrying parts of a circuit breaker of equivalent
normal load.
The circuit breaker is of vital importance as a device used for making and breaking an
electrical circuit under conditions of varying severity. The functions are [1]:
• It must be capable of closing and carrying full load currents for long periods.
• Under prescribed conditions, it must open automatically to disconnect the load or
some small overload.
• It must successfully and rapidly interrupt the heavy currents, which flow when a
short circuit occurs.
• With its contacts open, the gap must withstand the circuit voltage.
• It must be capable of closing on to a circuit in which a fault exists and
immediately re-opening to clear a fault from the system

Reference: Arc Control in Circuit Breakers: Low Contact Velocity Paperback – 1 Jan 2017 by Dr Kesorn Pechrach PhD (Author)