Electrical Fundamentals

Circuit Breakers
“A device designed to open and close a circuit by nonThe National Electricto open(NEC) and automatically on
automatic mean...
Contacts that make and extinguish components:
Arc A circuit breaker and two simple electrical arcs quickly.
chutes dissipa...
Quick operation selection process is based
Circuit Breaker is required to immediately
A breaker is designed drawn when the...
There are two types of control
processes associated with a
breaker:

Arc Control
Non-Arc Control

Arc Control
Non-Arc Control
• Breakers selection must be
capable of showing protection
during abnormal conditions, yet
allow for the normal operations...
Circuit Breakers-General
Circuit Breakers are selected based on their Ratings.

Voltage
Voltage
Outside of the selection i...
Circuit Breakers-General

Frequency
• Frequency selection is solely based on the application
that the breaker will serve.
...
Circuit Breakers-General

Short Circuit Current Capability
• A breaker (and associated switchgear) has to show
150% protec...
Circuit Breakers-General

What is an Asymmetrical Fault?

• This type of fault is one that has
a sign wave that is unpredi...
Circuit Breakers-General
If a 13.8 kv distribution system experiences the worst case
fault, how much power could be releas...
Circuit Breakers-General

Closing or Latching Current
• Otherwise known as “control current or control power”.
• Must be r...
Circuit Breakers-General

Arc Extinction
• Breakers are rated on how well and by what method an arc
is extinguished.
• An ...
Circuit Breakers-General

ARC Characteristics
• An arc is ionized air
across a potential
source.

• Arc temperatures
appro...
Circuit Breakers-General
Arc Extinction Process
• The arc is first elongated .
• An elongated arc is cooled
by air, oil, v...
Circuit Breakers-General

Arc Elongation Process
• Arcs are elongated through the following processes:

Thermally (through...
Circuit Breakers-General

Arc Elongation Process
Circuit Breakers-General

Types of Arc Extinction Methods
•

Air

•

Magnetic

•

Oil

•

Air-Blast

•

Vacuum

•

SF6

•
...
Circuit Breakers-General

There are several types of circuit breakers
used in the power industry:
1.

Molded Case (LV)

2....
Breaker Components

All breakers contain the same basic components:
•

Stationary Main Line Contacts

•

Moveable Mainline...
Breaker Components

Contacts
• Contacts are used to
make and break electrical
connections from Line to
Load.
• Contacts ar...
Breaker Components

Mainline and Arcing Contacts

Mainline Contacts are used to transfer power from
• Stationary Mainline ...
Breaker Components

Mainline and Arcing Contacts
• Mainline contacts
require immense force
(up to several
thousand pounds)...
Breaker Components

Mainline and Arcing Contacts

Arcing Contacts are designed to protect the Mainline
Arcing Contacts are...
Breaker Components

Mainline and Arcing Contacts

Arcing Contacts close first and open last. This
ensures that the arc wil...
Breaker Components

Auxiliary Contacts
• Auxiliary Contacts are smaller contacts found
internal or external to a breaker.
...
Breaker Components

Disconnects

• The disconnect are the devices that physically engage
into the switchboard.
• The disco...
Breaker Components

• Primary Disconnects are
located on the back of the
breaker cradle.
• They function to positively
eng...
Breaker Components

Disconnects
• Finger Type disconnects
can be located on all styles
of breakers.
• Spring Loaded Finger...
Breaker Components

Disconnects
• Tulip Clip disconnects
are common on all styles of
breakers.
• Use Spring Loaded
Wafers ...
Breaker Components

Disconnects
• Tulip Clips are primarily used
in High Current applications
over the Finger Type because...
Breaker Components

Disconnects
• Secondary Disconnects are similar to Secondary Contacts
in that they are used for contro...
Breaker Components

Arc Interrupting Devices
• Arc Chutes are normally
found on all Low Voltage
air cooled breakers.
• Arc...
Breaker Components

Arc Interrupting Devices
• Arc Chutes are normally
made of a non-conducing
insulator called Melamine
w...
Breaker Components

Arc Interrupting Devices
• Vacuum Interrupters
found on the GE PowerVac
Breakers serve the same
functi...
Breaker Components

Arc Interrupting Devices
• In the Magnetic System, the arc is
drawn away from the contact faces my
mag...
Breaker Components

Arc Interrupting Devices

• SF6 breakers use SulfurHexaflouride gas to extinguish
the arc at pressures...
Breaker Components

Arc Interrupting Devices

SF6 Arc Extinction
Breaker Components

Arc Interrupting Devices
• Oil Filled breakers are
found on older High
Voltage distribution
systems.
•...
Breaker Components

Closing Devices Devices
• Closing Devices can be mechanical,
electrical, or hydraulic (air or oil).

•...
Breaker Components

Closing Devices Devices
• Manually operated
breakers are found on
most lighting systems,
smaller auxil...
Breaker Components

Closing Devices Devices
• Electrically operated
breakers are found on
larger distribution
systems and ...
Breaker Components

Closing Devices Devices

For most electrically operated breakers, interlocks and
The Closing Coil (CC)...
Breaker Components

Closing Devices Devices

Once the Closing Coil has energized, the Charging
Motor energizes. The Chargi...
Breaker Components

Closing Devices Devices
• Hydraulic Systems such as air or oil are used
for very large breakers.

• Oi...
Breaker Components

Interlocks Devices
• Interlocks are designed to
prevent a breaker from operating
during unsafe conditi...
Breaker Components

Interlocks Devices
Mechanical Interlocks
• Positive Interlock: Mechanically couples the breaker such
t...
Breaker Components

Interlocks Devices
Mechanical Interlocks
• Spring Discharge Interlock: This interlock will discharge
t...
Breaker Components

Interlock Devices
Mechanical Interlocks
• Key Interlocks: Allows the coordination between two or
more ...
Breaker Components

Interlock Devices
Mechanical Interlocks
• Safety Roll-In Stop: Regardless of the position of the
racki...
Breaker Components

Interlock Devices
Mechanical Interlocks
• Rating Interference Interlock: This is a mechanical
interloc...
Breaker Components

Interlock Devices
Electrical Interlocks
• Interlock Switches: “Interlock Switch” is a General Term.
Th...
Breaker Components

Frame Assembly or “Cradle”
• The Frame Assembly or
“Cradle” provides structural
•support for size brea...
Breaker Applications

Low Voltage - Molded Case Breakers
• Molded Case Breakers are used
in systems of up to 600 volts.
• ...
Breaker Applications

Low Voltage - Molded Case Breakers
• Molded Case breakers have
• Molded Case Breakers are extremely
...
Breaker Applications

Low Voltage - Molded Case Breakers
Breaker Applications

Low Voltage - Molded Case Breakers
• Traditional LV breakers have
limited trip functions.
• Limited ...
Breaker Applications

Low Voltage - Molded Case Breakers
Breaker Applications

Spectra Series
and

Low Voltage Breakers
Breaker Applications

• Designed for quicker response times.
• WavePro and Spectra
Series is GE's New
• Implements micro-p...
Breaker Applications

•

•
•
•

System Integration of Engine
Generator, UPS & Distribution
Switchgear
New Solid State Prod...
Breaker Applications



Improved Reliability &
Uptime, Breaker
Maintenance Video



15 Digit Catalog Number,
Ordered Via...
Breaker Applications

 True Closed Door Drawout Design
 Robust Metal Frame Construction
 Up to 72 Secondary Disconnects...
Breaker Applications

 Engraved Metal Nameplate with 15 Digit Catalog
Number.
 Designed & Tested to ANSI Standards
 Six...
Breaker Applications











Long Time & Inst. Protection (standard)
Interchangeable Rating Plug (standard)
Set...
Breaker Applications










9-Function Solid State Trip Unit
Liquid Crystal Display, 5-Button
Keypad & Non-Vola...
Breaker Applications

All the Features of MVT Plus™ and...
 Power Leader™ Communications
 Full Function Metering
Current...
Breaker Applications

 Metering & Relaying CT’s Mount
Directly to Base.

 New Design Does Not Require Side
Supports

 R...
Breaker Applications

Medium Voltage Breakers
• Medium Voltage breakers range from
601- 15,000 volts.

• A variety of brea...
Breaker Applications

Medium Voltage Breakers
• Magna-Blast breakers are
generally used for gas and
steam turbine generato...
Breaker Applications

Medium Voltage Breakers
• Vacuum Breakers can be used for
generator output but normally are not.

• ...
Breaker Applications

Medium Voltage Breakers

• PowerVac breakers located in either
the top or bottom (or both) control
c...
Breaker Applications

Medium Voltage Breakers

• Access to the breaker is
accomplished by opening the outer
cover door of ...
Breaker Applications

Medium Voltage Breakers

• The breaker is designed
with a racking bolt that will
remove the breaker ...
Breaker Applications

High Voltage Breakers
• SF6 Breakers are used in
applications of 15,000 volts or
higher.

• They hav...
Breaker Applications

High Voltage Breakers
• The interrupters are mounted in a
grounded tank with each phase
separated.

...
Breaker Applications

High Voltage Breakers

SF6 Arc Extinction
Breaker Applications

High Voltage Breakers
• Oil Filled Breakers were used
as the earliest of the High
Voltage Breakers.
...
Breaker Applications

High Voltage Breakers

• Mainline contacts were
submerged in a oil bath.

• The oil was susceptible ...
Breaker Applications

High Voltage Breakers

• The breakers became out dated
with the advent of microprocessor
technology....
Breaker Applications

Disconnect Switches
• Disconnect Switches are used
for a variety of applications.

• They can be fou...
Breaker Applications

Disconnect Switches
• Disconnect switches are not
breakers and should never be
used as one.

• In so...
Breaker Precautions

Precautions with Breakers
• Always completely de-energize
any breaker before servicing it.
• Always t...
Breaker Precautions

Precautions with Breakers
• Avoid touching contact surfaces
with bare hands. Oil from your
finger tip...
Breaker Precautions

Precautions with Breakers

• Arc Chutes should be kept
clean and generally free of
defects.
Breaker Precautions

Precautions with Breakers

• Ensure that the breaker
charging mechanisms is
completely discharged pri...
Breaker Precautions

Precautions with Breakers

• Never override an interlock.
• A breaker in the TEST
position is still a...
Breaker Precautions

Precautions with Breakers
• For SF6 Breakers, ensure
that O2 concentrations are kept
less than 18%. T...
Breaker Precautions

Precautions with Breakers

• For Vacuum Breakers,
ensure that each interrupter
has the proper vacuum ...
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Circuit breakers

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Published in: Education

Circuit breakers

  1. 1. Electrical Fundamentals Circuit Breakers
  2. 2. “A device designed to open and close a circuit by nonThe National Electricto open(NEC) and automatically on automatic means and Code the circuit NEMA(AB) define a circuit breaker as: without damage to itself a predetermined overcurrent when properly applied within it’s rating”.
  3. 3. Contacts that make and extinguish components: Arc A circuit breaker and two simple electrical arcs quickly. chutes dissipate has break electrical connections.
  4. 4. Quick operation selection process is based Circuit Breaker is required to immediately A breaker is designed drawn when the eliminate the arc that is to provide quick breaker upon the usecomponent Arc a isolation separate or justoffromto voltage of a and type prior Control contracts closing. desired. source.
  5. 5. There are two types of control processes associated with a breaker: Arc Control Non-Arc Control Arc Control
  6. 6. Non-Arc Control
  7. 7. • Breakers selection must be capable of showing protection during abnormal conditions, yet allow for the normal operations of its associated components. Motor Protection Curve
  8. 8. Circuit Breakers-General Circuit Breakers are selected based on their Ratings. Voltage Voltage Outside of the selection isthat the upon voltage not • Proper voltage ensures based voltage class is broken Voltage United States, the breaker will class. down into: nominal duty (damage to components exceed it’s 0 - 600 volts - Low Voltage due to heat). 0 - 1000 volts - Low Voltage 601 - 15,000 volts - Medium Voltage • Proper voltage and greater the current carry 1001 ensures that - High Voltage capacity of15,001 and greater - High Voltage the breaker is not exceeded. Even though the voltage classes are different, breaker selection remains the same.
  9. 9. Circuit Breakers-General Frequency • Frequency selection is solely based on the application that the breaker will serve. • Operating at the improper frequency could change the characteristics of how the breaker would operate. This is primary concern for breakers that rely upon inductive trip mechanisms. • Breakers are generally designed for 50 and 60 Hz. Other models are available based of specific applications.
  10. 10. Circuit Breakers-General Short Circuit Current Capability • A breaker (and associated switchgear) has to show 150% protection for the worse case asymmetrical fault that could occur possibly occur within a distribution system.
  11. 11. Circuit Breakers-General What is an Asymmetrical Fault? • This type of fault is one that has a sign wave that is unpredictable. • The breaker has to quickly isolate and cool the subsequent arc. • What would happen if the arc were left uncontrolled:
  12. 12. Circuit Breakers-General If a 13.8 kv distribution system experiences the worst case fault, how much power could be release instantaneously? Power • A Worst Case Fault is a direct short to ground with a resistance of .01 . Power = (3) x Voltage x Current x pf • 13.8 kv is an RMS value and has to be converted to a Peak (assume that system pf is .85) Value: Peak Volts Power = (3) x (29,278.5 volts) x (2.93 x 10 6 amps) x .85 13.8 kv / .707 = 19,519 volts x 150% Power = 218.7 x 10 6 KW ! 29,278.5 volts This number is purely theoretical but illustrates how much Ohm’s Law power a fault of this magnitude has and why a structurally sound breaker is Resistance Current = Voltage /required. Current = 29,278.5 volts / .01 Instantaneous Current = 2.93 x 10 6 amps
  13. 13. Circuit Breakers-General Closing or Latching Current • Otherwise known as “control current or control power”. • Must be rated high enough to provide sufficient strength to overcome the mechanical forces associated with breaker but low enough to prevent damage to components due to excessive heat.
  14. 14. Circuit Breakers-General Arc Extinction • Breakers are rated on how well and by what method an arc is extinguished. • An arc is formed when the contacts of a breaker separate due to voltage across the contacts and current supplied to a load.
  15. 15. Circuit Breakers-General ARC Characteristics • An arc is ionized air across a potential source. • Arc temperatures approach 35,000 oF or more. • No arc when breakers contacts are shut. • Uncontrolled arcs will damage equipment and are a personnel hazard.
  16. 16. Circuit Breakers-General Arc Extinction Process • The arc is first elongated . • An elongated arc is cooled by air, oil, vacuum, and SF6 • Arc elongation occurs Thermally (convection) and Magnetically. • Arcs lose energy as it is broken up and moves further from the source.
  17. 17. Circuit Breakers-General Arc Elongation Process • Arcs are elongated through the following processes: Thermally (through convection) Magnetically (arc is pulled into arc chutes)
  18. 18. Circuit Breakers-General Arc Elongation Process
  19. 19. Circuit Breakers-General Types of Arc Extinction Methods • Air • Magnetic • Oil • Air-Blast • Vacuum • SF6 • Hybrid (combination of the above)
  20. 20. Circuit Breakers-General There are several types of circuit breakers used in the power industry: 1. Molded Case (LV) 2. Air Breakers (LV and MV) 3. Magnetic (MV) 4. Vacuum (MV) 5. Air-Blast (MV and HV) 6. SF6 (HV) 7. Oil (HV) - not used anymore But...
  21. 21. Breaker Components All breakers contain the same basic components: • Stationary Main Line Contacts • Moveable Mainline Contacts • Arcing Contacts • Auxiliary Contacts • Arc Interrupting Device • Closing Mechanism • Opening Mechanism • Control Mechanism • Interlocks • Frame Assembly
  22. 22. Breaker Components Contacts • Contacts are used to make and break electrical connections from Line to Load. • Contacts are designed to have the absolute lowest electrical resistance. • There are four common types of contacts found inside a circuit breaker. Each contact has a specific function.
  23. 23. Breaker Components Mainline and Arcing Contacts Mainline Contacts are used to transfer power from • Stationary Mainline Contacts: Connected to frame Line to Load. They are normally the largest and assembly and does not move. Referred to as the Load. most expensive of all of the contacts. There is one Moveable per phase. There are two types of set•of contacts Mainline Contacts: Connected to a moveable armature. Referred Mainline Contacts: to as the Line.
  24. 24. Breaker Components Mainline and Arcing Contacts • Mainline contacts require immense force (up to several thousand pounds) for proper contact. • Proper contact ensures that there will no high resistance connections across the contact face. • However, in vacuum breakers (shown), the contacts are held shut by as little at 12 psi.
  25. 25. Breaker Components Mainline and Arcing Contacts Arcing Contacts are designed to protect the Mainline Arcing Contacts are cheaper and easier to replace than Contacts from damage due to excessive arc. Mainline Contacts.
  26. 26. Breaker Components Mainline and Arcing Contacts Arcing Contacts close first and open last. This ensures that the arc will be drawn across the arcing contacts vice the Mainline contacts.
  27. 27. Breaker Components Auxiliary Contacts • Auxiliary Contacts are smaller contacts found internal or external to a breaker. • Used to provide 120 volts or less for control functions, interlocks, and indication. • Normally mounted to the frame or “cradle “ along the back side of the breaker
  28. 28. Breaker Components Disconnects • The disconnect are the devices that physically engage into the switchboard. • The disconnects are broken into two types: Primary and Secondary.
  29. 29. Breaker Components • Primary Disconnects are located on the back of the breaker cradle. • They function to positively engage the breaker into the switchboard. • The Load and Line sides of the circuit are connect through the disconnects. • There are two basic types of Primary Disconnects: Finger Type and Tulip Clip. Disconnects
  30. 30. Breaker Components Disconnects • Finger Type disconnects can be located on all styles of breakers. • Spring Loaded Fingers engage metal tabs on the switchboard for positive connection. • Made from Stainless Steel, Bronze, Plated Aluminum, and Silver • Easier maintenance than the Tulip Clip disconnects.
  31. 31. Breaker Components Disconnects • Tulip Clip disconnects are common on all styles of breakers. • Use Spring Loaded Wafers that form a circle. This circle is can be located on the switchboard or the breaker. • Each phase has an associated post that will engage the wafer to complete the circuit.
  32. 32. Breaker Components Disconnects • Tulip Clips are primarily used in High Current applications over the Finger Type because of an increase in surface area and higher current densities. CT Breaker
  33. 33. Breaker Components Disconnects • Secondary Disconnects are similar to Secondary Contacts in that they are used for control features, interlocks, and indication.
  34. 34. Breaker Components Arc Interrupting Devices • Arc Chutes are normally found on all Low Voltage air cooled breakers. • Arc Chutes function to rapidly extinguish an arc that has been caused by separated contacts. • Arc Chutes are located around each set of Mainline Contacts (1 per phase).
  35. 35. Breaker Components Arc Interrupting Devices • Arc Chutes are normally made of a non-conducing insulator called Melamine with a ceramic liner. • Arc Chutes are designed for ease of removal for inspection. • Arc Chutes normally have an additional plate that located to each side that will insulate each phase from ground.
  36. 36. Breaker Components Arc Interrupting Devices • Vacuum Interrupters found on the GE PowerVac Breakers serve the same function as Arc Chutes. • The Arc is extinguished in a vacuum sealed container vice air. • This type of arc interruption is found in Medium Voltage Systems
  37. 37. Breaker Components Arc Interrupting Devices • In the Magnetic System, the arc is drawn away from the contact faces my magnetic attraction. • The arc is drawn into the arc interrupter where is it subsequently cut into smaller arcs. • As the arc travels outward, its path is increased, thereby losing energy. • Primarily used in Medium Voltage systems and is found in the MagnaBlast breaker design.
  38. 38. Breaker Components Arc Interrupting Devices • SF6 breakers use SulfurHexaflouride gas to extinguish the arc at pressures from 70 90 psig. • These breakers are used in High Voltage applications.
  39. 39. Breaker Components Arc Interrupting Devices SF6 Arc Extinction
  40. 40. Breaker Components Arc Interrupting Devices • Oil Filled breakers are found on older High Voltage distribution systems. • Oil is used instead of air or gas to extinguish an arc.
  41. 41. Breaker Components Closing Devices Devices • Closing Devices can be mechanical, electrical, or hydraulic (air or oil). • The type of closing power depends upon breaker size, location, and use. • Closing action can be done locally or remotely. • Closing action may require that interlocks be met. • Closing power (normally 450 volts or less) maybe required in some applications
  42. 42. Breaker Components Closing Devices Devices • Manually operated breakers are found on most lighting systems, smaller auxiliary loads, and some 480 vac distribution applications. • These types of breakers are generally used in “onoff” applications and have very little if any automatic functions.
  43. 43. Breaker Components Closing Devices Devices • Electrically operated breakers are found on larger distribution systems and loads. • These breakers are desirable for remote or automatic functions. • May use a motor or other device. • These types of breakers will normally have interlocked inputs.
  44. 44. Breaker Components Closing Devices Devices For most electrically operated breakers, interlocks and The Closing Coil (CC) is generally a small relay permissives must be met before Power Source will be that is powered from a Control the closing coil energized. 120 volts) (normally
  45. 45. Breaker Components Closing Devices Devices Once the Closing Coil has energized, the Charging Motor energizes. The Charging Motor physically moves the linkages to close the breaker.
  46. 46. Breaker Components Closing Devices Devices • Hydraulic Systems such as air or oil are used for very large breakers. • Oil is not used as much as air due to the potential for contact contamination from oil leaks. • High pressure air is preferred but has limited cycling capabilities because of the need to recharge the source. • Air-Blast breakers are used for some generator breaker applications.
  47. 47. Breaker Components Interlocks Devices • Interlocks are designed to prevent a breaker from operating during unsafe conditions. • Interlocks maybe mechanical, electrical or a combination of both. • Interlocks should never be overridden. • Interlocks can be easily damage rendering them inoperative.
  48. 48. Breaker Components Interlocks Devices Mechanical Interlocks • Positive Interlock: Mechanically couples the breaker such that the racking mechanism can only be engaged if the breaker is in the OPEN position. This interlock prevents inserting or removing a CLOSED BREAKER. • Negative Interlock: Mechanically places the breakers trip shaft in the “tripped “ position. Prevents closing a breaker in any position other than the TEST or CONNECTED positions after the racking mechanisms have been disengaged.
  49. 49. Breaker Components Interlocks Devices Mechanical Interlocks • Spring Discharge Interlock: This interlock will discharge the closing springs to provide a mechanical saftey feature such that the breaker is discharged as well as open when it is removed from the equipment. • Padlocks: Provisions can be provided to enable the breaker to be locked out during certain operations or maintenance. Padlocks can either prevent closing the breaker and/or preventing engaging the racking mechanism.
  50. 50. Breaker Components Interlock Devices Mechanical Interlocks • Key Interlocks: Allows the coordination between two or more deices such that certain operations must be performed in sequence on one device before proceeding to operate the next device. The above coordination is accomplished by special locks that hold the key captive until the proper conditions are met. This allows the key to be removed and inserted into another special lock on another device in order to properly operate it.
  51. 51. Breaker Components Interlock Devices Mechanical Interlocks • Safety Roll-In Stop: Regardless of the position of the racking mechanism, it is impossible to manually insert the breaker into the rails beyond the Disconnect/Test position. • Safety Roll-Out Stop: This interlock prevents the breaker from being rolled out of the equipment accidentally. This stop has to be manually released prior to breaker removal onto the transfer truck. • Gag Spring Interlock: This breaker ensures that only breakers with freely operating closing springs can be inserted into the equipment. If the closing springs have been gagged for breaker adjustments, it would be possible to place the breaker in an operational status.
  52. 52. Breaker Components Interlock Devices Mechanical Interlocks • Rating Interference Interlock: This is a mechanical interlock that is coded such that the only properly rated breaker can be inserted into its designated location.
  53. 53. Breaker Components Interlock Devices Electrical Interlocks • Interlock Switches: “Interlock Switch” is a General Term. The basic function of these switches is to block electrical closing signals and to open the closing mechanisms charging circuit whenever a breaker is being inserted or removed. To determine which switch provide what features, electrical schematics should be referenced.
  54. 54. Breaker Components Frame Assembly or “Cradle” • The Frame Assembly or “Cradle” provides structural •support for size breaker The Frame the will be expressed in “amps”. components. ••The continuous some fashion of the It is bolted in current rating to breaker will never exceed the breaker the switchboard. frame size. • May have provisions for wheels or lift truck attachments for ease of removal during maintenance or inspection.
  55. 55. Breaker Applications Low Voltage - Molded Case Breakers • Molded Case Breakers are used in systems of up to 600 volts. • A “Molded Case Breaker” is one that is assembled as an integral unit in a supportive and enclosed housing of insulated material (NEC and NEMA defined).
  56. 56. Breaker Applications Low Voltage - Molded Case Breakers • Molded Case breakers have • Molded Case Breakers are extremely factory calibrated very little if reliable and require and sealed any elements. maintenance. • Unauthorized modifications may • They are designed to be “turned on” render this breaker incapable of and for the operator to be able to walk performing its intended functions away. and may jeopardize the manufactures warranty.
  57. 57. Breaker Applications Low Voltage - Molded Case Breakers
  58. 58. Breaker Applications Low Voltage - Molded Case Breakers • Traditional LV breakers have limited trip functions. • Limited to Thermal and Magnetic automatic trips. • Not used as much for power distribution because of limited protective trips and slower response times.
  59. 59. Breaker Applications Low Voltage - Molded Case Breakers
  60. 60. Breaker Applications Spectra Series and Low Voltage Breakers
  61. 61. Breaker Applications • Designed for quicker response times. • WavePro and Spectra Series is GE's New • Implements micro-processor based Line technology. of Low Voltage Power Circuit • Used for on all major LV distribution Breakers. centers as well as some limited MV applications. • It Builds on the • More Experience of the trips than automatic protective traditional, older molded case AKR Line, with breakers which make them better for Improved Reliability distribution purposes. And Functionality
  62. 62. Breaker Applications • • • • System Integration of Engine Generator, UPS & Distribution Switchgear New Solid State Products Power Management System Reliability is Directly Tied to User’s Uptime
  63. 63. Breaker Applications  Improved Reliability & Uptime, Breaker Maintenance Video  15 Digit Catalog Number, Ordered Via OSB GE-1-STOP  New Robust Design, No Side Support Required  Fully Assembled, Rigid, Aligned Substructure (No Adjustments)
  64. 64. Breaker Applications  True Closed Door Drawout Design  Robust Metal Frame Construction  Up to 72 Secondary Disconnects  Interchangeable Escutcheon Mounted Trip Units  Integral Charging Handle on MO & EO Breakers  Breaker Position Indicator Flag  Bell Alarm w/wo Lockout (target std)  Charge After Close Mechanism  “Hidden On” Button
  65. 65. Breaker Applications  Engraved Metal Nameplate with 15 Digit Catalog Number.  Designed & Tested to ANSI Standards  Six Breaker Frame Sizes: 800, 1600, 2000, 3200, 4000, 5000 Amp  200,000 AIC Short Circuit Rating  Improved Packaging  Optional “Power Management Ready”  Padlock Provisions for Both Breaker & Substructure
  66. 66. Breaker Applications         Long Time & Inst. Protection (standard) Interchangeable Rating Plug (standard) Settings via Rotary Switches Short Time & GF Protection (optional) Ground Fault Integrated into Rating Plug Switchable Ground Fault (Not UL) Optional Target Module Provides Status LED’s for Battery Check, Trip Unit Health Monitor, Longtime Pickup, and Trip Targets (LED’s) for Overload, Short Circuit, and Ground Fault Interchangeable with MicroVersaTrip Plus and PM Trip Units
  67. 67. Breaker Applications         9-Function Solid State Trip Unit Liquid Crystal Display, 5-Button Keypad & Non-Volatile Memory Standard Phase-Selectable Ammeter, +/-2% Accuracy Interchangeable Rating Plugs Built-In, Long-Life Lithium Battery for Cold Setup Easy Upgrade to Power Management Trip Targets, Trip Information, and Trip Operations Counters Optional Zone Selective Interlocking
  68. 68. Breaker Applications All the Features of MVT Plus™ and...  Power Leader™ Communications  Full Function Metering Current Total Power Voltage Frequency Energy Demand Real Power Peak Demand  Optional Protective Relaying Under voltage Current Unbalance Over voltage Power Reversal Voltage Unbalance Power Direction Setup
  69. 69. Breaker Applications  Metering & Relaying CT’s Mount Directly to Base.  New Design Does Not Require Side Supports  Relaying CT’s Fit in Shallow Substructures  Padlocking Provisions Standard on All Sizes, Preventing Breaker Insertion  Shallow Substructure for 3200 & 4000A Frames  New Rail/Wheel Guidance System, Improved rating rejection system  Neutral & Trip Unit Disconnect Moved to Secondary Disconnect Block  More Options With Shutters & Position Switches
  70. 70. Breaker Applications Medium Voltage Breakers • Medium Voltage breakers range from 601- 15,000 volts. • A variety of breakers can be found in the category including: Spectra Series WavePro Series PowerVac Vacuum Breakers Magna-Blast Air-Blast
  71. 71. Breaker Applications Medium Voltage Breakers • Magna-Blast breakers are generally used for gas and steam turbine generator breakers. • The breakers are large and require a special housing and associated motor controller. • Breakers must have a sound maintenance program due to the size of the breaker and mechanical stresses placed upon them during operation. CT Breaker and 8000 Series Controller
  72. 72. Breaker Applications Medium Voltage Breakers • Vacuum Breakers can be used for generator output but normally are not. • Primarily used for medium voltage distribution centers of 13.8 kV and below. • Experience less wear and tear because of component size. • Normally used in indoor applications.
  73. 73. Breaker Applications Medium Voltage Breakers • PowerVac breakers located in either the top or bottom (or both) control cubicles of the GE PowerVac switchgear.
  74. 74. Breaker Applications Medium Voltage Breakers • Access to the breaker is accomplished by opening the outer cover door of the cubicle. • The lower cubicle stores protective relays, current, and potential transformers.
  75. 75. Breaker Applications Medium Voltage Breakers • The breaker is designed with a racking bolt that will remove the breaker from the switchgear. • Breaker can be removed completely if the provided lift truck is used.
  76. 76. Breaker Applications High Voltage Breakers • SF6 Breakers are used in applications of 15,000 volts or higher. • They have replaced Oil breakers as industry standard. • Normally connected directly to an isolated phase bus. • Simple designs and construction. • Relatively small space required for placement.
  77. 77. Breaker Applications High Voltage Breakers • The interrupters are mounted in a grounded tank with each phase separated. • The interrupters are operated by a hydraulic operating mechanism • The main contacts are connected directly to the isolated phase bus. • SF6 gas (an insulator) is used to rapidly extinguish the arc. • Preferred over Oil Filled Breakers
  78. 78. Breaker Applications High Voltage Breakers SF6 Arc Extinction
  79. 79. Breaker Applications High Voltage Breakers • Oil Filled Breakers were used as the earliest of the High Voltage Breakers. • Increased Maintenance requirements makes them undesirable • Large Contact surfaces and no arcing contacts caused excessive pitting at the contact faces. • Still maybe found in older distribution systems.
  80. 80. Breaker Applications High Voltage Breakers • Mainline contacts were submerged in a oil bath. • The oil was susceptible to moisture contamination which lowered its dielectric strength leading to flash over.
  81. 81. Breaker Applications High Voltage Breakers • The breakers became out dated with the advent of microprocessor technology. • Response times where generally slow and the breaker generally had limited protective features.
  82. 82. Breaker Applications Disconnect Switches • Disconnect Switches are used for a variety of applications. • They can be found in in all voltage classes. • They can be manually or motor operated. •Are used to isolate a portion of a distribution system, typically during maintenance.
  83. 83. Breaker Applications Disconnect Switches • Disconnect switches are not breakers and should never be used as one. • In some cases they can be inserted into a breaker cubical. • Some switches are grounded to ensure that equipment (generator stators) are safe prior to maintenance. • Grounded disconnect switches are normally interlocked with a supply breaker to ensure that both are not shut at the same time.
  84. 84. Breaker Precautions Precautions with Breakers • Always completely de-energize any breaker before servicing it. • Always treat a breaker as if it is Always check voltages between SHUT and Energized. phases and between each phase and ground. • Only QUALIFIED personnel • should ever attempttheservice Always ensure that to Control any type of breaker. OSHA Power source has been removed article 1910.331 defines what prior to Racking In or Out anya Qualified breaker. person is. • Always use a procedure when performing any type of inspection on a breaker.
  85. 85. Breaker Precautions Precautions with Breakers • Avoid touching contact surfaces with bare hands. Oil from your finger tips will damage the contact face. breakers should be • All kept setting breaker on • Avoidclean ofawater, dirt, its side or and metal. could damage the back. This Secondary Disconnects, Auxiliary Contacts, or any of the control modules. Some breakers are equipped with oil filled over current devices. This oil may leak out and damage the breaker.
  86. 86. Breaker Precautions Precautions with Breakers • Arc Chutes should be kept clean and generally free of defects.
  87. 87. Breaker Precautions Precautions with Breakers • Ensure that the breaker charging mechanisms is completely discharged prior to breaker disassembly.
  88. 88. Breaker Precautions Precautions with Breakers • Never override an interlock. • A breaker in the TEST position is still as dangerous as a breaker that is racked in. • Ensure the proper lubricant is used for the right breaker. There is a difference!
  89. 89. Breaker Precautions Precautions with Breakers • For SF6 Breakers, ensure that O2 concentrations are kept less than 18%. This will ensure that there is not a sustained arc.
  90. 90. Breaker Precautions Precautions with Breakers • For Vacuum Breakers, ensure that each interrupter has the proper vacuum IAW its associated tech manual.
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