The need for proper maintenance of circuit breakers is very important, as circuit breakers may remain idle, either open or closed, for long periods. They are also often located in remote areas, which make their inspection and maintenance more difficult and expensive. To improve reliability of the power system through various system analyses it is necessary to know power system topology configuration. Real time and remote monitoring seems to be perfect solution for equipment conditioning and status monitoring. First remote monitoring of circuit breakers introduced is Supervisory Control and Data Acquisition (SCADA) system. This system is used for CB status monitoring and remote breaker operation. This system monitors status of CB mechanical contacts and transfers it in real time to central place. Condition monitoring is a relatively newer concept that has come about primarily because of recent developments of electronic sensors and data acquisition equipment that have made this idea not only technically feasible but also economically attractive. It is know that the breaker health, status and operating characteristics can be affected by extreme ambient temperatures, and by other prevailing conditions such as mechanism operating energy levels, control voltages, operating frequency of the equipment, its age, and its maintenance history among others. Collecting real time information about these variations, breaker operation and status would provide a good data source to improve breakermaintenance, synchronous operation, topology analysis and other analysis that rely on circuitbreaker status or condition data.
associated with sending a large group of people and maximize the number of participants. Pricing will be provided on a case- by-case basis depending on the customer’s speciﬁcations. Customers shall provide the following conditions during onsite training on Emax maintenance:
Under normal operating conditions of use, as determined by UL 489 or ANSI Standards (see table C) and controlled by tests, MASTERPACT circuit breakers do not require maintenance. However, these circuit breakers exceed, without maintenance and additional costs, the endurances required by standards. See tables A and C. Service maintenance by a field service representative will extend the endurance according to table B. This service can be performed on site and consists in changing contacts, arc chutes and some other parts.
A dead-tank high voltage circuitbreaker is one in which the vessel (or tank) containing the electrical current breaking mechanism (or interrupter) and insulating medium is at ground voltage potential considered “dead” in terms of voltage hazard potential. This design allows for the tank to be safely contactable during operating conditions and located within reach of maintenance staff. Usually however, maintenance is still conducted under de-energised conditions. An advantage of dead-tanks is that ladders and or elevated work platforms are not usually needed during maintenance outages. The high voltage conductors are held at safe distances away from the grounded voltage metal tank by means of tall insulation bushings. The bushings allow for the high voltage conductors to feed down through them and into the tank, at all times remaining insulated from the metal tank enclosure wall. The design offers a structurally stable, four leg, horizontal tank design with high seismic withstand capability. The dead-tank design’s main advantage however is that it allows for the inclusion of multiple low voltage, bushing type, current transformers on both sides of the
Note: Power is supplied to the bilge pumps, high water alarm, stereo memory, and galvanic protection system through the constant power circuit, independent of the battery switches’ positioning (i.e., these components receive power even with the switches in the OFF position). Each twin engine boat is equipped with a battery parallel system (Figure 4-34). The battery parallel switch allows you to start either engine off of either battery. The switch should be in the OFF position during normal use. Should one of the START batteries be low on cranking power, turn the battery parallel switch ON. This allows the engine with the low battery to start by using power from the other engine’s battery. Once both
Apart from resistive components, other passive components, e.g., inductors and capacitors, could also be used together with semiconductor devices for current limiting. As a series-connected component, inductors are used widely for CL purposes, but the voltage overshoot caused by inductive currents must be taken into account to ensure the safety of the semiconductor devices. On the contrary, there is no overvoltage problem for capacitors as CL components, but the current cannot be limited properly because the limitation process is indirect. Another option is forming a combination of capacitor and inductor as a resonant circuit. The impedance of this kind of circuit could change from negligible to a high value by adding semiconductor switches, which is considered more suitable as a CL component than a pure inductor or capacitor.
Type II systems give a “stressor-based prediction” , which combine the average component lifetime of a type I model with information about the environmental conditions experienced by a given asset. A type II system takes account of the different ways an asset can be used. For example, some circuit breakers are exercised frequently for switching operations, whereas others are expected to operate only to clear faults, and may remain unexercised for years at a time. These different environmental factors can exert different stresses on the breaker - one experiences regular, low level wear while the other experiences infrequent, high levels of wear - and consequently, one particular model of breaker could fail at different rates depending on whether it is used primarily for switching or fault clearance.
HV320 is an ideal alternative to thermal and manual circuit breakers in DC input applications. It has wide variety of uses in the automotive industry, such as PCB trace / device protection and DC motors and solenoid actuator current limit protection. These devices are typically used in windows and seat adjustment operations as well as automatic trunk opening mechanisms. Since these devices are operated manually, they can remain energized by the operator even after the mechanical lever has reached its end of travel. In this case, back EMF that normally opposes the supply voltage will drop to zero and a large current surge can begin to flow. HV320 can accurately be programmed to trip the current. In industrial applications, HV320 can offer broad solutions in DC solenoid-operated valves, DC motors and other electromagnetic loads.
Low-voltage circuit breakers also made for direct-current (DC) applications. Example; DC supplied for subway lines. A direct current needs a special breaker because the arc does not have a natural tendency to go out on each half cycle as for alternating current. A direct current circuitbreaker will blow-out coils which it generates a magnetic field that rapidly stretches the arc when interrupting direct current. Small circuit breakers are either installed directly in equipment, or are arranged in a breaker panel.
Single-pole circuitbreaker: it usually operates with two tripping coils and one closing coil. Each bay contains 3 single-pole breakers, one per phase. When a single-phase fault occurs, a single-pole breaker opens the affected phase separately, without needing to open all the phases and enabling a single-phase reclosing.
These breakers are available with either noninterchangeable trip (designated Type TJJ) or interchangeable trip (designated Type TJK and THJK). Type TJJ product numbers include frame, trip, Cu/Al line, and load lugs factory assembled. If line lugs are not required on the breaker, eliminate “WL” from product number, and subtract price of line lugs from price of complete breaker. TJK breakers are available in two frames, 400 ampere frame (125 to 400 amperes) and 600 ampere frame (250 to 600 amperes). Trip units are not interchangeable between frames. “Complete CircuitBreaker” price includes frame, trip unit, Cu/Al line, and load lugs. Unit will be shipped unassembled unless order specifies “must be factory assembled.” If line lugs are not required, eliminate “WL” from product number and subtract price of line lugs from price of complete breaker.
The Basic Insulation Level or B.I.L of plant and equipment is determined by manufacturers and is defined by the IEEE Guide for Recommended Electrical Clearances and Insulation Levels in Air Insulated Electrical Power Substations as: The electrical strength of insulation expressed in terms of the crest value of a standard lightning impulse under standard atmospheric conditions (IEEE, 2007) . All Substation major plant and equipment has a Basic Insulation Level (B.I.L) specified by the manufacturer which will contribute to the B.I.L that is chosen to be used at a particular site. The piece of plant or equipment in the Substation with the lowest B.I.L will ultimately determine what the overall B.I.L for a particular site will be, and it is typical that the equipment within a Substation will be selected at a particular B.I.L.
Furthermore, coil voltage variation compensation and idle time compensation are described to perform an automatic adjustment of the next operation, based on the learning of the past history of the circuitbreaker performance. The paper also highlights the importance of the compensation for opening / closing times. Some errors may be generated by the deviation of the operation time due to an insufficient compensation especially due to pause time. Thus the multiprocessor based system described in the paper can compensate the closing / opening time and eliminates control error for different types of Load.
In Coil Voltage Variation Compensation, the coil voltage is varied The 4 points of “closing and opening times” are set during circuitbreaker commissioning for R, Y and B phases. These timings will be according to the standard values of coil voltage and air pressure from the circuit breaker’s specification. “closing and opening times” will vary with line frequency also. If any of these 3 parameter changes, the corresponding waiting time is compensated in actual mechanical time. Following graph shows the close and open time against coil voltage variation for one pole with in accuracy of 1.0 mSec.
ELCB has become one of the home safety systems in our life today. ELCB has reset button which is to reclosed circuitbreaker when the tripping occur. Today, many of people busy with work and usually not at home. The problem are during the over current, short circuit or current leakage at live conductor, it can trip the circuitbreaker “OFF” and cut off the whole house power supply. This situation can make certain important component or equipment cannot be operated. Most household ELCB need to be reclosed manually during tripping, hence is a troublesome thing for user who is not at home and may be would take long time to reset on back the button at circuitbreaker. The main mechanism in operation is tripping coil which is it can operation either in live or off condition. This ELCB will operate when current is exceeding the rating of the current ELCB. This high current not flows into equipment after ELCB tripped. It will flow directly into ground by using ground rod. This ground rod must has the lower resistance it because easy to flow high current. There are two types of ELCB:-
control of the hybrid HVDC breaker is utilised to compensate for the time delay of the fast disconnector. Another method [12 – 15] to produce CZ in the mechanical switch involves current oscillation. In general, this topology comprises two mechanical switches; a main breaker and an isolation switch (as with the ABB hybrid breaker); the main breaker is parallelly connected to commutation and energy absorbing paths. The main breaker supports the continuous current ﬂ ow; the isolation switch provides dielectric separation of the load after fault clearance thereby avoiding metal oxide varistor (MOV) thermal overload, while the solid-state switches in the commutation path only conduct during the interruption process. A series combination of a capacitance C and inductance L is incorporated into the commutation path; thus there will be an oscillating current between the main breaker and commutation path. The line current originally ﬂ owing through the main breaker is sinusoidally transferred into the commutation path. At this point, a CZ arises in the nominal path and the main breaker can interrupt with zero current. As the line current continues to ﬂ ow through the LC commutation circuit, the voltage across the capacitor C charges to a voltage within the capability of the grid. At this voltage, the remaining energy stored in the line inductance is dissipated in the energy absorption path (MOV), forcing the line current to decrease. There are two current commutation modes; namely active commutation if C is pre-charged, otherwise passive commutation.
As a part of ongoing research on MVDC, a 400V DC testbed is being developed in FREEDM systems center. The 400V system is shown in figure 1.4. It can be seen that there are several loads connected to DC bus some of which could be sensitive loads which need faster fault isolation in order to protect them from damage. In a real MVDC system, fault severity could be even higher owing to higher bus voltage. This thesis focuses on developing DC solid state circuitbreaker hardware for 400V system shown in figure 1.4. Simulations are also performed for a 7.5kV MVDC system using different devices and results are compared.