15-Circuit-Breaker-Basics-2018

Prévia do material em texto

1 
Fundamentals of Circuit Breaker Maintenance 
© AVO Training Institute, Inc. 2018 
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Moderator 
n  Ron Spataro 
AVO Training Institute Marketing Manager 
3 
Q&A 
n  Send us your 
questions and 
comments during 
the presentation 
4 
Today’s Presenter 
Mike Carter 
 
AVO Training Institute, Senior Instructor and 
Curriculum Advisor 
 
5 
 
•  Definition 
•  A circuit breaker is an automatically operated electrical 
switch designed to protect an electrical circuit from damage 
caused by excess current from an overload or short circuit. 
Its basic function is to interrupt current flow after a fault is 
detected. 
•  Unlike a fuse, which operates once and then must be 
replaced, a circuit breaker can be reset (either manually or 
automatically) to resume normal operation. 
 
Definition and Purpose of Circuit Breakers 
6 
 
•  Definition 
•  Circuit breakers are made in varying sizes, from small 
devices that protect low-current circuits or individual 
household appliance, up to large switchgear designed to 
protect high voltage circuits feeding an entire city. 
•  The generic function of a circuit breaker, RCD or a fuse, as 
an automatic means of removing power from a faulty system 
is often abbreviated as OCPD (Over Current Protection 
Device). 
 
Definition and Purpose of Circuit Breakers 
7 
 
•  Purpose 
•  Interconnection of multiple generator sources into an 
electrical grid required development of circuit breakers with 
increasing voltage ratings and increased ability to safely 
interrupt the increasing short-circuit currents produced by 
networks. 
•  Simple air-break manual switches produced hazardous arcs 
when interrupting high voltages; these gave way to oil-
enclosed contacts, and various forms using directed flow of 
pressurized air, or of pressurized oil, to cool and interrupt 
the arc. 
 
Definition and Purpose of Circuit Breakers 
8 
 
•  Purpose 
•  All circuit breaker systems have common features in their 
operation, but details vary substantially depending on the 
voltage class, current rating and type of the circuit breaker. 
•  The circuit breaker must first detect a fault condition. 
•  In small mains and low voltage circuit breakers, this is 
usually done within the device itself. 
•  Circuit breakers for large currents or high voltages are 
usually arranged with protective relay pilot devices to sense 
a fault condition and to operate the opening mechanism. 
 
Definition and Purpose of Circuit Breakers 
9 
 
•  Purpose 
•  These typically require a separate power source, such as a 
battery, although some high-voltage circuit breakers are self-
contained with current transformers, protective relays, and 
an internal control power source. 
•  Once a fault is detected, the circuit breaker contacts must 
open to interrupt the circuit; this is commonly done using 
mechanically stored energy contained within the breaker, 
such as a spring or compressed air to separate the contacts. 
 
Definition and Purpose of Circuit Breakers 
10 
 
•  Purpose 
•  Circuit breakers may also use the higher current caused by 
the fault to separate the contacts, such as thermal 
expansion or a magnetic field. 
•  Small circuit breakers typically have a manual control lever 
to switch off the load or reset a tripped breaker, while larger 
units use solenoids to trip the mechanism, and electric 
motors to restore energy to the springs. 
 
Definition and Purpose of Circuit Breakers 
11 
 
•  Purpose 
•  The circuit breaker contacts must carry the load current 
without excessive heating, and must also withstand the heat 
of the arc produced when interrupting (opening) the circuit. 
•  Contacts are made of copper or copper alloys, silver alloys 
and other highly conductive materials. 
•  Service life of the contacts is limited by the erosion of 
contact material due to arcing while interrupting the current. 
 
Definition and Purpose of Circuit Breakers 
12 
 
 
Air, Low- Voltage Power Circuit Breakers 
13 
 
•  Visual and Mechanical Inspection 
•  Inspect physical and mechanical condition. 
•  Inspect anchorage, alignment, and grounding. 
•  Verify that all maintenance devices are available for 
servicing and operating the breaker. 
•  Prior to cleaning the unit, perform as-found tests, if required. 
•  Clean the unit. 
•  Inspect arc chutes. 
•  Inspect moving and stationary contacts for condition, wear, 
and alignment. 
 
Air, Low- Voltage Power Circuit Breakers 
14 
 
•  Visual and Mechanical Inspection 
•  Verify that primary and secondary contact wipe and other 
dimensions vital to satisfactory operation of the breaker are 
correct. 
•  Perform all mechanical operator and contact alignment tests 
on both the breaker and its operating mechanism in 
accordance with manufacturer’s published data. 
 
Air, Low- Voltage Power Circuit Breakers 
15 
 
•  Visual and Mechanical Inspection 
•  Inspect bolted electrical connections for high resistance 
using one or more of the following methods: 
•  Use of a low-resistance ohmmeter 
•  Verify tightness of accessible bolted electrical connections 
by calibrated torque-wrench method in accordance with 
manufacturer’s published data or Neta Table 100.12. 
•  Perform a thermographic survey 
 
Air, Low- Voltage Power Circuit Breakers 
16 
 
•  Visual and Mechanical Inspection 
•  Verify cell fit and element alignment. 
•  Verify racking mechanism operation. 
•  Use appropriate lubrication on moving current-carrying parts 
and on moving and sliding surfaces. 
•  Perform adjustments for final protective device settings in 
accordance with coordination study provided by end user. 
•  Perform as-left tests. 
•  Record as-found and as-left operation counter readings. 
 
Air, Low- Voltage Power Circuit Breakers 
17 
 
•  Electrical Test 
•  Perform resistance measurements through bolted 
connections with a low-resistance ohmmeter. 
•  Perform insulation-resistance tests for one minute on each 
pole, phase-to-phase and phase-to-ground with the circuit 
breaker closed, and across each open pole. Apply voltage in 
accordance with manufacturer’s published data. In the 
absence of manufacturer’s published data, use Neta Table 
100.1. 
 
Air, Low- Voltage Power Circuit Breakers 
18 
 
•  Electrical Test 
•  Perform a contact/pole-resistance test. 
•  (Optional) Perform insulation-resistance tests on all control 
wiring with respect to ground. The applied potential shall be 
500 volts dc for 300-volt rated cable and 1000 volts dc for 
600-volt rated cable. Test duration shall be one minute 
•  Determine long-time pickup and delay, short-time pickup 
and delay, ground-fault pickup and delay and instantaneous 
pickup current by primary current injection. 
 
Air, Low- Voltage Power Circuit Breakers 
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•  Electrical Test 
•  (Optional)Test functions of the trip unit by means of 
secondary injection. 
•  Perform minimum pickup voltage test on shunt trip and close 
coils in accordance with Neta Table 100.20. 
•  Verify correct operation of auxiliary features such as trip and 
pickup indicators, zone interlocking, electrical close and trip 
operation, trip-free, antipump function, and trip unit battery 
condition. 
 
Air, Low- Voltage Power Circuit Breakers 
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•  Electrical Test 
•  Reset all trip logs and indicators. 
•  Verify operation of charging mechanism. 
•  Test Values – Visual and Mechanical 
•  Compare bolted connection resistance values to values of 
similar connections. Investigate values which deviate from 
those of similar bolted connections by more than 50 percent 
of the lowest value. 
 
Air, Low- Voltage Power Circuit Breakers 
21 
 
•  Test Values – Visual and Mechanical 
•  Bolt-torque levels should be in accordance with 
manufacturer’s published data. In the absence of 
manufacturer’s published data, use Neta Table 100.12. 
•  Results of the thermographic survey. 
•  Settings shall complywith coordination study 
recommendations. 
•  Operations counter should advance one digit per close-open 
cycle. 
 
Air, Low- Voltage Power Circuit Breakers 
22 
 
•  Test Values – Electrical 
•  Compare bolted connection resistance values to values of 
similar connections. Investigate values which deviate from 
those of similar bolted connections by more than 50 percent 
of the lowest value. 
•  Insulation-resistance values of breakers should be in 
accordance with manufacturer’s published data. In the 
absence of manufacturer’s published data, use Neta Table 
100.1. Values of insulation resistance less than this table or 
manufacturer’s recommendations should be investigated. 
 
Air, Low- Voltage Power Circuit Breakers 
23 
 
•  Test Values – Electrical 
•  Microhm or dc millivolt drop values should not exceed the 
high levels of the normal range as indicated in the 
manufacturer’s published data. If manufacturer’s data is not 
available, investigate values that deviate from adjacent 
poles or similar breakers by more than 50 percent of the 
lowest value. 
•  Insulation-resistance values of control wiring should be 
comparable to previously obtained results but not less than 
two megohms. 
 
Air, Low- Voltage Power Circuit Breakers 
24 
 
•  Test Values – Electrical 
•  Pickup values and trip characteristic should be as specified 
and within manufacturer’s published tolerances. 
•  Minimum pickup voltage on shunt trip and close coils should 
be in accordance with manufacturer’s published data. In the 
absence of manufacturer’s published data, refer to Neta 
Table 100.20. 
•  Auxiliary features should operate in accordance with 
manufacturer’s published data. 
 
Air, Low- Voltage Power Circuit Breakers 
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Circuit Breakers, Air, Medium-Voltage 
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•  Visual and Mechanical Inspection 
•  Inspect physical and mechanical condition. 
•  Verify that all maintenance devices are available for 
servicing and operating the breaker. 
•  Perform operator analysis (first-trip) test. 
•  Prior to cleaning the unit, perform as-found tests, if required. 
•  Inspect arc chutes. 
•  Inspect moving and stationary contacts for condition, wear, 
and alignment. 
 
Circuit Breakers, Air, Medium-Voltage 
27 
 
•  Visual and Mechanical Inspection 
•  If recommended by manufacturer, slow close/open breaker 
and check for binding, friction, contact alignment, contact 
sequence, and penetration. 
•  Verify that contact sequence is in accordance with 
manufacturer’s published data. 
•  Perform all mechanical operation tests on the operating 
mechanism in accordance with manufacturer’s published 
data. 
 
Circuit Breakers, Air, Medium-Voltage 
28 
 
•  Visual and Mechanical Inspection 
•  Inspect bolted electrical connections for high resistance 
using one or more of the following methods: 
•  Use of a low-resistance ohmmeter, verify tightness of 
accessible bolted electrical connections by calibrated 
torque-wrench or perform a thermographic survey. 
•  Verify cell fit and element alignment. 
•  Verify racking mechanism operation. 
 
Circuit Breakers, Air, Medium-Voltage 
29 
 
•  Visual and Mechanical Inspection 
•  Inspect puffer operation. 
•  Use appropriate lubrication on moving current-carrying parts 
and on moving and sliding surfaces. 
•  (Optional) Perform time-travel analysis. 
•  Perform as-left tests. 
•  Record as-found and as-left operation-counter readings. 
 
Circuit Breakers, Air, Medium-Voltage 
30 
 
•  Electrical Tests 
•  Perform resistance measurements through bolted 
connections with a low-resistance ohmmeter. 
•  Perform insulation-resistance tests for one minute on each 
pole, phase-to-phase and phase-to-ground with the circuit 
breaker closed, and across each open pole. Apply voltage in 
accordance with manufacturer’s published data. In the 
absence of manufacturer’s published data, use Table 100.1. 
 
Circuit Breakers, Air, Medium-Voltage 
31 
 
•  Electrical Tests 
•  Perform a contact/pole-resistance test. 
•  With the breaker in a test position, perform the following 
tests: 
•  Trip and close breaker with the control switch. 
•  Trip breaker by operating each of its protective relays. 
•  Verify mechanism charge, trip-free, and antipump functions. 
•  (Optional)Perform minimum pickup voltage tests on trip and 
close coils 
 
Circuit Breakers, Air, Medium-Voltage 
32 
 
•  Electrical Tests 
•  (Optional) Perform power-factor or dissipation-factor tests 
with breaker in both the open and closed positions and each 
bushing equipped with a power-factor/capacitance tap. In 
the absence of a power-factor/ capacitance tap, perform hot-
collar tests. 
•  (Optional) Perform a dielectric withstand voltage test on 
each phase with the circuit breaker closed and the poles not 
under test grounded. Test voltage should be in accordance 
with manufacturer’s published data or Neta Table 100.19. 
 
Circuit Breakers, Air, Medium-Voltage 
33 
 
•  Electrical Tests 
•  Verify blowout coil circuit continuity. 
•  Verify operation of cubicle space heaters. 
•  Test Values – Visual and Mechanical 
•  Compare first-trip operation time and trip-coil current 
waveform to manufacturer’s published data. In the absence 
of manufacturer's published data, compare first-trip 
operation time and trip coil current waveform to previously 
obtained results. 
 
Circuit Breakers, Air, Medium-Voltage 
34 
 
•  Test Values – Visual and Mechanical 
•  Compare bolted connection resistance values to values of 
similar connections. Investigate values which deviate from 
those of similar bolted connections by more than 50 percent 
of the lowest value. 
•  Bolt-torque levels should be in accordance with 
manufacturer’s published data. 
•  Results of the thermographic survey. 
•  Compare travel and velocity values to manufacturer’s 
published data and previous test data. 
 
Circuit Breakers, Air, Medium-Voltage 
35 
 
•  Test Values – Visual and Mechanical 
•  Operations counter should advance one digit per close-open 
cycle. 
•  Test Values – Electrical 
•  Compare bolted connection resistance values to values of 
similar connections. Investigate values which deviate from 
those of similar bolted connections by more than 50 percent 
of the lowest value. 
 
Circuit Breakers, Air, Medium-Voltage 
36 
 
•  Test Values – Electrical 
•  Insulation-resistance values of circuit breakers should be in 
accordance with manufacturer’s published data. In the 
absence of manufacturer’s published data, use Neta Table 
100.1. Values of insulation resistance less than this table or 
manufacturer’s recommendations should be investigated. 
•  Microhm or dc millivolt drop values shall not exceed the high 
levels of the normal range as indicated in the manufacturer’s 
published data. If manufacturer’s data is not available, 
investigate values that deviate from adjacent poles or similar 
breakers by more than 50 percent of the lowest value. 
 
Circuit Breakers, Air, Medium-Voltage 
37 
 
•  Test Values – Electrical 
•  Breaker mechanism charge, close, open, trip, trip-free, and 
antipump features shall function as designed. 
•  Minimum pickup for trip and close coils shall be in 
accordance with manufacturer’s published data. 
•  Power-factor or dissipation-factor values shall be compared 
with previous test results of similar breakers or 
manufacturer’s published data. 
 
Circuit Breakers, Air, Medium-Voltage 
38 
 
•  Test Values – Electrical 
•  Power-factor or dissipation-factor and capacitance values 
should be within ten percent of nameplate rating for 
bushings. Hot collar tests are evaluated on a milliampere/
milliwatt loss basis, and the results should be compared to 
values of similar bushings. 
•  If no evidence of distress or insulation failure is observed by 
the end of the total time of voltage application during the 
dielectric withstand voltage test, the circuit breaker is 
consideredto have passed the test. 
 
Circuit Breakers, Air, Medium-Voltage 
39 
 
•  Test Values – Electrical 
•  The blowout coil circuit should exhibit continuity. 
•  Cubicle space heaters should be operational. 
 
Circuit Breakers, Air, Medium-Voltage 
40 
 
 
Circuit Breakers, Vacuum, Medium-Voltage 
41 
 
•  Visual and Mechanical Inspection 
•  Inspect physical and mechanical condition. 
•  Inspect anchorage, alignment, and grounding. 
•  Verify that all maintenance devices are available for 
servicing and operating the breaker 
•  (Optional)Perform operator analysis (first-trip) test. 
•  Prior to cleaning the unit, perform as-found tests, if required. 
•  Clean the unit. 
•  Inspect vacuum bottle assemblies. 
 
Circuit Breakers, Vacuum, Medium-Voltage 
42 
 
•  Visual and Mechanical Inspection 
•  Measure critical distances such as contact gap as 
recommended by the manufacturer. 
•  If recommended by the manufacturer, slow close/open the 
breaker and check for binding, friction, contact alignment, 
contact sequence, and penetration. 
•  Perform all mechanical operation tests on the operating 
mechanism in accordance with manufacturer’s published 
data. 
 
Circuit Breakers, Vacuum, Medium-Voltage 
43 
 
•  Visual and Mechanical Inspection 
•  Inspect bolted electrical connections for high resistance 
using one or more of the following methods: 
•  1. Use of a low-resistance ohmmeter. 
•  2. Verify tightness of accessible bolted electrical connections 
by calibrated torque-wrench method in accordance with 
manufacturer’s published data. In the absence of 
manufacturer’s published data, use Neta Table 100.12. 
•  3. Perform a thermographic survey 
 
Circuit Breakers, Vacuum, Medium-Voltage 
44 
 
•  Visual and Mechanical Inspection 
•  Verify cell fit and element alignment. 
•  Verify racking mechanism operation. 
•  Inspect vacuum bellows operation. 
•  Use appropriate lubrication on moving current-carrying parts 
and on moving and sliding surfaces. 
•  Perform time-travel analysis. 
•  Perform as-left tests. 
•  Record as-found and as-left operation counter readings. 
 
Circuit Breakers, Vacuum, Medium-Voltage 
45 
 
•  Electrical Test 
•  Perform resistance measurements through bolted 
connections with a low-resistance ohmmeter. 
•  Perform insulation-resistance tests for one minute on each 
pole, phase-to-phase and phase-to-ground with circuit 
breaker closed and across each pole with the breaker open. 
Apply voltage in accordance with manufacturer’s published 
data. In the absence of manufacturer’s published data, use 
Table 100.1. 
 
Circuit Breakers, Vacuum, Medium-Voltage 
46 
 
•  Electrical Test 
•  (Optional)Perform insulation-resistance tests on all control 
wiring with respect to ground. 
•  Perform a contact/pole-resistance test. 
•  With breaker in a test position, perform the following tests: 
•  1. Trip and close breaker with the control switch. 
•  2. Trip breaker by operating each of its protective relays. 
•  3. Verify mechanism charge, trip-free, and antipump 
functions. 
 
Circuit Breakers, Vacuum, Medium-Voltage 
47 
 
•  Electrical Test 
•  (Optional) Perform minimum pickup voltage tests on trip and 
close coils. 
•  (Optional) Perform power-factor or dissipation-factor tests on 
each pole with the breaker open and each phase with the 
breaker closed. 
•  (Optional) Perform power-factor or dissipation-factor tests on 
each bushing equipped with a power-factor/capacitance tap. 
In the absence of a power-factor/ capacitance tap, perform 
hot-collar tests. 
 
Circuit Breakers, Vacuum, Medium-Voltage 
48 
 
•  Electrical Test 
•  Perform a vacuum bottle integrity (dielectric withstand 
voltage) test across each vacuum bottle with the breaker in 
the open position in strict accordance with manufacturer’s 
published data. 
•  (Optional) Perform a dielectric withstand voltage test on 
each phase with the circuit breaker closed and the poles not 
under test grounded. Test voltage should be in accordance 
with manufacturer’s published data. In the absence of 
manufacturer’s published data, use Neta Table 100.19. 
 
Circuit Breakers, Vacuum, Medium-Voltage 
49 
 
•  Test Values – Visual and Mechanical 
•  Compare first-trip operation time and trip-coil current 
waveform to manufacturer’s published data. In the absence 
of manufacturer's published data, compare first-trip 
operation time and trip coil current waveform to previously 
obtained results. 
•  Mechanical operation and contact alignment should be in 
accordance with manufacturer’s published data. 
•  Compare bolted connection resistance values to values of 
similar connections. Investigate values which deviate from 
those of similar bolted connections by more than 50 percent 
of the lowest value. 
 
Circuit Breakers, Vacuum, Medium-Voltage 
50 
 
•  Test Values – Visual and Mechanical 
•  Bolt-torque levels should be in accordance with 
manufacturer’s published data. In the absence of 
manufacturer’s published data, use Neta Table 100.12. 
•  Results of the thermographic survey. 
•  Compare travel and velocity values to manufacturer’s 
published data and previous test data. 
•  Operation counter should advance one digit per close-open 
cycle. 
 
Circuit Breakers, Vacuum, Medium-Voltage 
51 
 
•  Test Values – Electrical 
•  Compare bolted connection resistance values to values of 
similar connections. Investigate values which deviate from 
those of similar bolted connections by more than 50 percent 
of the lowest value. 
•  Insulation-resistance values of circuit breakers should be in 
accordance with manufacturer’s published data. In the 
absence of manufacturer’s published data, use Table 100.1. 
 
Circuit Breakers, Vacuum, Medium-Voltage 
52 
 
•  Test Values – Electrical 
•  Microhm or dc millivolt drop values shall not exceed the high 
levels of the normal range as indicated in the manufacturer’s 
published data. If manufacturer’s data is not available, 
investigate values that deviate from adjacent poles or similar 
breakers by more than 50 percent of the lowest value. 
•  Breaker mechanism charge, close, open, trip, trip-free, and 
antipump features shall function as designed. 
 
Circuit Breakers, Vacuum, Medium-Voltage 
53 
 
•  Test Values – Electrical 
•  Minimum pickup for trip and close coils shall be in 
accordance with manufacturer’s published data. In the 
absence of data use NetaTable 100.20. 
•  Power-factor or dissipation-factor values shall be compared 
to manufacturer’s published data. In the absence of 
manufacturer’s published data the comparison shall be 
made to similar breakers. 
 
Circuit Breakers, Vacuum, Medium-Voltage 
54 
 
•  Test Values – Electrical 
•  Power-factor or dissipation-factor and capacitance values 
should be within ten percent of nameplate rating for 
bushings. Hot collar tests are evaluated on a milliampere/
milliwatt loss basis, and the results should be compared to 
values of similar bushings. 
•  If no evidence of distress or insulation failure is observed by 
the end of the total time of voltage application during the 
vacuum bottle integrity test, the test specimen is considered 
to have passed the test. 
 
Circuit Breakers, Vacuum, Medium-Voltage 
55 
 
•  Test Values – Electrical 
•  If no evidence of distress or insulation failure is observed by 
the end of the total time of voltage application during the 
dielectric withstand voltage test, the test specimen is 
considered to have passed the test. 
•  Heaters should be operational. 
 
Circuit Breakers, Vacuum, Medium-Voltage 
56 
•  We discussed the definition and history of circuit breakers. 
•  We addressed the Neta MTS maintenance standards for the 
following circuit breaker types: 
•  Low voltage air circuit breakers. 
•  Medium voltage air circuit breakers. 
•  Medium voltage vacuum breakers. 
•  In future we will discuss oil circuit breakers of all voltageclasses as well as SF6 gas breakers. 
 
 
 
 
Summary 
 
57 
Save the Date for Our Next Webinar 
Tuesday September 18, 2018 at 1pm – 2pm CDT 
 
Title: Vacuum Interrupter Technology 
 
Presented by: Greg Richmond 
AVO Training Specialist - Instructor 
58 
Megger®	Recommended	Equipment	
n  EGIL 
•  For substations 245kV and below 
•  Vacuum CBs, OCBs, and gang operated 
SF6 CBs 
•  CBs with 1 break per phase and 1 operating 
mechanism (gang op) 
n  TM1800 
•  765kV substations and below 
•  Can be used on all circuit breakers 
•  16 main and 16 Resistor contacts 
per phase 
•  Gang operated or IPO 
•  OCBs, SF6, Vacuum, GIS, 
Airblast… 
•  Dualground™ testing 
n  CABA Win 
•  Interfaces with EGIL, TM1600, 
TM1700, and TM1800 
•  Detailed CB analysis and 
comparison to historical tests 
•  Simple consistent testing 
•  Fully customizable testing with 
Test Plan Editor (TPE) 
n  DLRO 100 
•  100A micro ohmmeter 
•  Smooth DC output 
•  Programmable ramp up, time on, ramp down, 
and output current 
•  Battery and line operated 
59 
 Questions? 
 
 
 
After more than 50 years, AVO Training remains a global leader in safety and 
maintenance training for the electrical industry. We deliver an engaging, hands-on 
experience for our clients in a professional, real-world environment. 
 
We strive to provide industry relevant courses in a practical and flexible learning 
environment through an ongoing commitment to quality service, integrity, 
instruction, and client satisfaction. 
 
Our goal is to convey practical job skills and career development for our clients 
and students by saving lives through a world-class learning experience. 
© AVO Training Institute, Inc. 2018