1、IEEE Guide for Breaker Failure Protection of Power Circuit BreakersIEEE Std C37.119-2016(Revision of IEEE Std C37.119-2005)IEEE Power and Energy SocietySponsored by the Power System Relaying CommitteeIEEE3 Park AvenueNew York, NY 10016-5997USAIEEE Std C37.119-2016(Revision of IEEE Std C37.119-2005)I
2、EEE Guide for Breaker Failure Protection of Power Circuit BreakersSponsor Power System Relaying Committee of the IEEE Power and Energy SocietyApproved 15 May 2016IEEE-SA Standards BoardAbstract: Methods to protect a power system from faults that are not cleared because of failure of a power circuit
3、breaker to operate or interrupt when called upon by a protective relay are described in this guide. The intent is to give the reader a guide in how to detect that a breaker has failed to clear a fault, and how to electrically isolate the fault after the breaker has failed to clear the fault. Additio
4、nally, schemes that provide primary protection of the power system from performance fail-ures of the power circuit breaker other than fault clearing failures such as failure to operate, either tripping or closing, manual or automatic, are also described. Such schemes, when applied, are typ-ically in
5、tegrated as a part of the overall breaker failure protection scheme. Also covered are recent practices that take advantage of new technologies.Keywords: BFP, breaker failure, breaker failure protection, circuit breaker, fault, IEEE C37.119, power systemThe Institute of Electrical and Electronics Eng
6、ineers, Inc.3 Park Avenue, New York, NY 10016-5997, USACopyright 2016 by The Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published 16 July 2016. Printed in the United States of America.IEEE is a registered trademark in the U.S. Patent non-infringement; and quality, a
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11、ss of a given IEEE standard.,112(9(176+$/,(%(/,$%/()25$1,5(03/$525 components needed for the interruption: (resistors or capacitors), are faulty; or the dielectric material in the interrupter is out of specification (low pressure, low temperature) or contaminated. If these are the causes for the fai
12、lure to interrupt, the breaker needs protection to prevent further damage. By the time the remote backup protection has operated, the arcing inside the interrupter will likely cause a phase-to-ground fault internal to the breaker. These internal faults may lead to explosions and fires. As a result o
13、f the slow clearing of the original fault, what could have been a minor breaker repair project, if the faulty breaker had been isolated in a timely manner, now may require the replacement of the breaker and possibly other equipment in close proximity to the faulty breaker. To summarize, when conside
14、ring if BFP systems will be applied, the following three fundamental attributes of the protection system need to be considered: Sensitivity: Can the overreaching protective relays in adjacent zones reliably detect faults in 100% of the zones to be backed up, considering infeed? Selectivity: Is it ac
15、ceptable to trip additional power system elements and loads that may be otherwise preserved by applying a BFP system? Speed: Is delayed clearing from remote backup for a breaker failure event acceptable for system stability, power quality, equipment through-fault stress, and equipment fault damage?
16、One final consideration in deciding to rely solely on remote backup is the cost and effort of relay setting maintenance. The analysis effort required for an even moderately complex networked system to consider all possible system configurations and current distributions that affect infeed for all po
17、ssible breaker failure scenarios is difficult. Assuming that the analysis has been performed adequately, even small changes to the network may require that all of this effort be repeated to prove that remote backup can be relied upon. For further information about remote backup, refer to IEEE Std C3
18、7.113. IEEE Std C37.119-2016 IEEE Guide for Breaker Failure Protection of Power Circuit Breakers 17 Copyright 2016 IEEE. All rights reserved. 5. Breaker failure modes BFP is designed to operate when the protective relaying scheme initiates a circuit breaker trip and that breaker does not interrupt t
19、he fault. BFP will be considered a subset of local backup protection. Breaker failure can be caused by a variety of situations, as follows: Failure to Trip: In failure to trip situations, the breaker contacts do not open after the trip circuit has been energized by the protective scheme. This could
20、be caused by an open or short in the trip circuit wiring or in the trip coil. It could also be the result of a mechanical problem in the breaker that prevents the contacts from opening; this condition is also known as “stuck breaker.” Failure to Clear: In these scenarios, the breaker contacts open,
21、but the arc is not extinguished and current continues to flow. This could be caused by mechanical problems (incomplete opening), or dielectric problems (such as contaminated oil or loss of vacuum). Failure to clear is significantly different from failure to trip in that the breaker auxiliary contact
22、s (52a and 52b) will change state, which indicates breaker opening. Because of this, an auxiliary contact position may not be a reliable indicator of a satisfactory breaker opening. Another failure to clear mode can occur in breakers with opening resistors. In this mode the resistor insertion contac
23、t operates successfully, but the main contacts fail. This results in a high impedance to current flow, but does not interrupt the flow of current. Both breaker failure modes can occur during high-current and low-current faults, including transfer trip from remote locations. There are also situations
24、 where a circuit breaker operates incorrectly, but is not classified as a breaker failure. These situations (as follows) are considered in system design, and may be incorporated within the breaker failure protective scheme: Loss of dielectric during non-fault conditions can prevent satisfactory inte
25、rruption of current if called upon, potentially leading to a true breaker failure. Loss of dielectric pressure can be detected in SF6 breakers using a gas density or pressure monitor. For loss of pressure below a cutoff point, breaker manufacturers typically recommend blocking the breaker tripping t
26、o prevent mechanical or electrical failure. In this case, the breaker failure scheme delay timer can be bypassed so that the BFP will operate with no intentional delay if a breaker failure initiate signal is received. Loss of mechanism energy storage during non-fault conditions can prevent satisfact
27、ory interruption of current in breakers that require stored energy for the opening stroke, if called upon, potentially leading to a true breaker failure. Loss of mechanism energy storage can be detected with pneumatic or hydraulic gauges, micro-switches, or undervoltage relays. For a loss of stored
28、energy below the rated minimum value, breaker manufacturers typically recommend blocking the tripping and closing of the circuit breaker to prevent mechanical or electrical failure. In this case, the breaker failure delay timer can be bypassed so that it will operate with no intentional delay. The b
29、reaker manufacturer might be consulted to verify the loss of energy storage is not a transient condition that could occur during the normal operation of the circuit breaker. Contact flashover in an open breaker can lead to catastrophic failure. This could be caused by a re-strike of an opening break
30、er or a surge through an already open breaker that produces dielectric breakdown across the contacts. Failure of a circuit breaker to close when called upon is not traditionally defined as a breaker failure condition, since it is not associated with a protective relay trip. This can, however, have s
31、ignificant impact on the power system and may need to be considered in the operating scheme. Many reclosing schemes include failure to close logic. IEEE Std C37.119-2016 IEEE Guide for Breaker Failure Protection of Power Circuit Breakers 18 Copyright 2016 IEEE. All rights reserved. Failure of a circ
32、uit breaker to close in the expected time while attempting to connect a generator to the system can cause severe damage to the generator and turbine if the breaker eventually closes when the generator is out of phase with the system. This can occur for a number of reasons, but especially if the brea
33、ker has sat for an extended time in very low ambient temperatures. It is recommended to isolate the breaker and operate it a few times before the synchronization is actually attempted. Protection schemes are also available to monitor the closing time of the breaker and trigger the breaker failure-to
34、close scheme if the close has not occurred within an appropriate time following synchronism. Non-fault related failures are also possible. An example would be failure to interrupt load current, or mechanical failure during switching operations. These failures can be addressed within more complex BF
35、P schemes. Numeric relays have some ability to identify impending failure of a circuit breaker. This can be accomplished by identifying degraded performance, such as changes in operate or clearing times. These schemes can also track predictive quantities such as accumulated interrupted current or nu
36、mber of operations. Breakers with single-phase tripping present additional constraints for BFP. 6. Breaker failure protection schemes This clause describes breaker failure schemes that have received acceptance by the industry and are used in utility power systems. Common elements of a breaker failur
37、e to interrupt scheme include the following: Scheme initiation by a breaker trip signal such as a protective relay that has operated to trip the breaker Determination that the breaker has tripped successfully by monitoring reset of an overcurrent element (50BF) that responds to each measured phase c
38、urrent (50P) and possibly the sum of these phase currents (50G), monitoring change in state of the circuit breaker auxiliary contact (52a, 52b, or 52aa), or some combination of these methods A timer Some means to trip and block closing of adjacent breakers Optional: A separate output contact to issu
39、e a re-trip signal to the circuit breaker before issuing a breaker failure output with sufficient margin such that successful opening of the circuit breaker will prevent an undesired breaker failure output Optional: A teleprotection channel to key a DTT and to cancel reclosing of remote circuit brea
40、kers Schemes are illustrated using logic diagrams. Many of the schemes could also be illustrated by using conventional dc control schematics. When choosing a scheme it is important that the interactive behavior of the aggregate components is well understood. Schemes vary in their degree of dependabi
41、lity versus security. Behavior peculiar to a particular type of relay can affect each scheme differently. Behavior can be impacted by equipment replacements and firmware upgrades. Factors to be aware of might include the following: IEEE Std C37.119-2016 IEEE Guide for Breaker Failure Protection of P
42、ower Circuit Breakers 19 Copyright 2016 IEEE. All rights reserved. Method of seal-in or latching of the primary relay output after fault detection Presence or absence of local current/fault detector supervision of the primary relay Sensitivity (pickup and dropout) of the 50BF current detectors Inter
43、action of the scheme with local and remote automatic reclosing Impacts of credible component failures such as welding shut of relay output contacts Reset of the BFP scheme 6.1 Basic breaker failure scheme Basic BFP provides a means to trip adjacent current sources if a fault is detected by protectiv
44、e relays and the associated breaker(s) fails to interrupt the fault. Figure 2 is a logic diagram showing a basic breaker failure scheme. Figure 3 shows a typical timing chart for this scheme. TimerBreaker Failure Scheme Output62-1AND50BFBFIFigure 2 Basic breaker failure scheme TOTAL FAULT CLEARING T
45、IMEFAULT CLEAREDFAULT OCCURSTIMEBREAKER FAILURE TIMER TIME (62-1) LOCAL BACKUP BREAKER INTERRUPT TIME94/86TRIPRELAYTIMEBREAKERINTERRUPT TIMETRANSFER TRIPTIMEMARGINTIMEPROTECTIVERELAYTIMEREMOTE BACKUP BREAKERINTERRUPT TIME50BF DROPOUT RESETBFI50BFFigure 3 Fault clearing timing chart The following two
46、 conditions are used to monitor proper breaker operation during a fault clearing operation: a) The presence of current flow in the breaker (50BF) and b) A protective relay trip signal (BFI). The breaker has failed to operate properly if both of these signals are present for a period greater than the
47、 expected breaker clearing time. A delay on pickup timer (62-1) is set to a time delay that exceeds the breaker normal clearing time with margin. If current is still flowing through the breaker when the timer times out it is determined that the breaker has failed. If the breaker operates properly, e
48、ither one or both of the 50BF or BFI inputs will de-assert and stop the operation of the timer. IEEE Std C37.119-2016 IEEE Guide for Breaker Failure Protection of Power Circuit Breakers 20 Copyright 2016 IEEE. All rights reserved. When a breaker failure scheme operates breaker failure timer (62-1) t
49、imes out, a number of actions are initiated by the scheme. Depending on design philosophy, the number of contacts required, the interrupting rating of the output contacts, or relay targeting requirements, auxiliary devices (94) may be used. Often, a lockout relay (86BF) is used as an auxiliary device. 6.2 Basic breaker failure with re-trip logic Re-trip is a separate output contact from the BFP intended to prevent undesired breaker failure operations and
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